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  • 1
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    A major change in the sedimentation regime in the Crotone Basin (Southern Italy) around 3.7-3.6 Ma (2014)
    Elsevier
    Details
    Publication Date: 2021-05-17
    Description: The Lower Pliocene succession of the Crotone Basin (Calabrian Arc, Southern Italy) is mainly comprised of blue-grey marly clay with good magnetic properties. Here the bio-magnetostratigraphic data indicate a mean sedimentation rate of about 12–15 cm/kyr. Around 3.7–3.6 Ma a major change in the sedimentation regime occurred: the blue-grey hemipelagic marls grade rapidly into silty marls with a significant increase in the terrigenous fraction and with abundant siliceous remains throughout the whole interval. Magnetic properties of these sediments are very poor, but an integrated calcareous plankton biostratigraphy (foraminifera and nannofossils) infers a high average sedimentation rate (about 50–60 cm/kyr). The abrupt onset of this sedimentation regime in the Crotone Basin is contemporaneous with a major unconformity already recognized in the northern sector of the basin, part of amajor reorganization phase in the whole Apenninic–Maghrebid Chain known as “Globorotalia puncticulata event”. Reports of coeval siliceous sediments in other marginal basins of the Apennines (Southern Calabria, Southern and Northern Apennines) suggest that this “siliceous event” might have been regionally extensive, having important palaeoceanographical implications.We infer that the “siliceous event” is characterized by a combined tectonic- and climate-induced change in palaeoceanographic conditions. The tectonic triggering factors may have been linked to two synchronous events in the Tyrrhenian–Apennine system: 1) the shortening event also known as “G. puncticulata event”, and 2) the coeval opening of the Vavilov Basin in the Tyrrhenian Sea which yielded profound influences in terms of physiography and characteristics of the Crotone Basin. The consequent uplift of the Southern Apennines would have increased sediment supply and availability of silica, resulting in eutrophication and enhanced silica preservation. Strong winter mixing and possibly upwelling conditions could have increased primary productivity during heavy isotope stages Gi4, Gi2 and MG8, at the onset of the “siliceous event”. This important event, lasting from ca. 3.6 Ma to ca. 3.2 Ma, would have recorded a peculiar transitional period before further climatic deterioration and more drastic palaeoceanographic changes occurred around 3.1 Ma, leading to cyclic sapropel deposition in the whole of the Mediterranean sea.
    Description: Published
    Description: 398-410
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Biostratigraphy ; Magnetostratigraphy ; Pliocene ; Calabrian Arc ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 2
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    The Afragola settlement near Vesuvius, Italy: The destruction and abandonment of a Bronze Age village revealed by archaeology, volcanology and rock-magnetism (2009)
    Elsevier
    Details
    Publication Date: 2021-06-15
    Description: Public works in progress in the Campanian plain north of Somma-Vesuvius recently encountered the remains of a prehistoric settlement close to the town of Afragola. Rescue excavations brought to light a Bronze Age village partially destroyed and buried by pyroclastic density currents (PDCs) of the Vesuvian Pomici di Avellino eruption (3.8 14C ka BP) and subsequently sealed by alluvial deposits. Volcanological and rockmagnetic investigations supplemented the excavations. Careful comparison between volcanological and archaeological stratigraphies led to an understanding of the timing of the damage the buildings suffered when they were struck by a series of PDCs. The first engulfed the village, located some 14 km to the north of the inferred vent, and penetrated into the dwellings without causing major damage. The buildings were able to withstand the weak dynamic pressure of the currents and deviate their path, as shown by the magnetic fabric analyses. Some later collapsed under the load of the deposits piled up by successive currents. Stepwise demagnetization of the thermal remanent magnetization (TRM) carried by potsherds embedded in the deposits yields deposition temperatures in the order of 260– 320 °C, fully consistent with those derived from pottery and lithic fragments from other distal and proximal sites. The fairly uniform temperature of the deposits is here ascribed to the lack of pervasive air entrainment into the currents. This, in turn, resulted from the lack of major topographical obstacles along the flat plain. The coupling of structural damage and sedimentological analyses indicates that the currents were not destructive in the Afragola area, but TRM data indicate they were still hot enough to cause death or severe injury to humans and animals. The successful escape of the entire population is apparent from the lack of human remains and from thousands of human footprints on the surface of the deposits left by the first PDCs. People were thus able to walk barefoot across the already emplaced deposits and escape the subsequent PDCs. The rapid cooling of the deposits was probably due to both their thinness and heat dissipation due to condensation of water vapour released in the mixture by magma–water interaction.
    Description: Published
    Description: 408–421
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: pyroclastic density current ; Bronze Age ; magnetic fabric ; deposition temperature ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Helium isotopes in hydrothermal volcanic fluids of the Azores Archipelago (2009)
    Elsevier
    Details
    Publication Date: 2021-06-25
    Description: We present the first helium isotope data for thermal waters and gas emissions on the islands of Terceira, Graciosa, Faial, Pico and Flores, as well as new data for Sao Miguel. The results allow us to track current mantle degassing associated with the Azores hot spot, to delineate its spatial distribution and to discuss its possible origin. As a general rule, we find that free gases tend to display somewhat higher 3He/4He ratio than groundwaters.We argue that this difference is likely due to radiogenic helium inputs to aquifers duringwater– rock interactions and, therefore, that gas phases are the fluid carriers with the most representative of mantle source signature. The measured 3He/4He ratios (normalized to the air ratio, Ra) range from lower-than-MORB values (5.23–6.07 Ra) on central Sao Miguel, to MORB values on Faial (8.53 Ra) and Flores (8.04 Ra) – located on either side of the Mid-Atlantic Ridge – and to plume-type values on Graciosa (11.2 Ra) and Terceira (13.5 Ra) where free gases also display ten times higher-than-MORB CO2/3He ratios (1.8–2.6×1010). Such a wide He isotopic range and its spatial distribution corroborate with available data for volcanic rocks, indicating that plume's head presently underlies the central part of the archipelago. The plume-type 3He/4He ratios on Terceira and Graciosa agree with geochemical and seismic evidence of a deep-rooted mantle plume feeding the Azores hot spot. Our finding that high 3He/4He ratios correspond to low 3He concentrations and high (arctype) CO2/3He values exclude a simple plume supply of 3He-rich primitive mantle. Instead, the simultaneity of both elevated CO2/3He and 3He/4He ratios is best explained by a 3He-rich contribution from the lower mantle diluted in a CO2-rich feeding plume that contains a recycled altered oceanic plate component. The alternative possibility of an enhanced time-integrated 3He/(U+Th) ratio in the Azores plume due to a greater compatibility of helium relative to U and Th during melting events is difficult to reconcile with the enriched pattern of volcanic rocks from the central islands. In any case, the Azores plume should derive from a mantle reservoir that could escape convective homogenization for a very long period of time, in agreement with subchondritic osmium isotopic ratios in volcanic rocks from the central islands of the archipelago.
    Description: Published
    Description: 70−80
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: hydrothemal fluids ; helium isotopes ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Integrated stratigraphic reconstruction for the last 80 kyr in a deep sector of the Sardinia Channel (Western Mediterranean) (2009)
    Elsevier
    Details
    Publication Date: 2021-07-14
    Description: A quantitative analysis of planktonic foraminifera, coupled with petrophysical and paleomagnetic measurements and 14C AMS calibrations, was carried out on a deep core recovered in the Sardinia Channel (Western Mediterranean Sea), during the CIESM Sub2 survey, providing an integrated stratigraphic time-framework over the last 80 kyr. Significant changes in the quantitative distribution of planktonic foraminifera allowed the identification of several eco-bioevents useful to accurately mark the boundaries of the eco-biozones widely recognised in the Western Mediterranean records and used for large scale correlations. Namely, 10 eco-biozones were identified based on the relative abundance of selected climate sensitive planktonic foraminiferal species. Sixteen codified eco-bioevents were correlated with the Alboran Sea planktonic foraminiferal data and four climatic global events (Sapropel S1, Younger Dryas, Greenland Isotope Interstadial 1, Greenland Isotope Stadial 2, Heinrich event H1-H6) were recognized. The eco-bioevents together with the 14C AMS calibrations allowed us to define an accurate age model, spanning between 2 and 83 kyr. The reliability of the age model was confirmed by comparing the colour reflectance (550 nm%) data of the studied record with the astronomically tuned record from the Ionian sea (ODP-Site 964). A mean sedimentation rate of about 7 cm/kyr included three turbidite event beds that were chronologically constrained within the relative low stand and lowering sea level phases of the MIS 4 and 3. The deep-sea sedimentary record includes a distinct tephra occurring at the base of the core which dates 78 ka cal. BP. The paleomagnetic data provide a well-defined record of the characteristic remanent magnetization that may be used to reconstruct the geomagnetic paleosecular variation for the Mediterranean back to 83 kyr.
    Description: Published
    Description: 725 - 737
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Integrated stratigraphy ; Late Neogene marine record ; Eco-bio-events ; Reflectance 550 nm % ; Sardinia Channel ; Western Mediterranean ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Monte Carlo technique in modeling ground motion coherence in sedimentary filled valleys (2009)
    Elsevier
    Details
    Publication Date: 2020-11-16
    Description: Using a Monte Carlo method based on a random walk in ad hoc N-dimensional phase space, we construct N random time series having prescribed coherence spatial decay. We apply the method in seismology by designing a numerical experiment to investigate how the coherence of the bedrock motion relates to the coherence of the surface ground motion in a sedimentary valley. The main features of the coherence behavior in the valley are found to tie in with data analysis and field observations.
    Description: Part of the research activities have been carried out by A. Caserta, for his PhD study, in cooperation with the Charles University in Prague (Czech Republic) and in the frame of the projects GACR 205/07/0502 and MSM 0021620860.
    Description: Published
    Description: 133-138
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Coherence of seismic waves ; Monte Carlo numerical simulations ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Present-day stress-field modelling of southern Italy constrained by stress and GPS data (2009)
    Elsevier
    Details
    Publication Date: 2020-11-16
    Description: The present-day tectonic setting of the Italian peninsula is very complex and involves competing geodynamic processes. In this context, southern peninsular Italy is characterised by extension along the Apenninic belt and in the Tyrrhenian margin and by transpression in the Apulia-Gargano region. The extension is well defined by means of geological, seismological, and contemporary stress data. For the latter only few data are available in the Apulia-Gargano region, leaving the state of stress in that area unresolved. Here we develop a finite-element model of the southern Italian region in order to predict the contemporary stress field. Our model predictions are constrained by model-independent observations of the orientation of maximum horizontal stress (SHmax), the tectonic regime, and the horizontal velocities derived from GPS observations. We performed a blind test with 31 newly acquired SHmax orientations in the Southern Apennines. These new data come from the analysis of borehole breakouts performed in 46 deep oil exploration wells ranging in depth from 1300 to 5500 m. The model results agree with the stress data that define a prevailing NW-SE SHmax orientation along the Apenninic belt and foredeep and thus are capable to predict the stress field where no stress information is available. We first analyse how much model predictions, based on older data, deviate from present-day stress data and then recalibrate the models based on our new stress data, giving insight into the resolution of both models and data. In the studied region, which is affected by low deformation rates, we find that geodetic data alone cannot resolve such low levels of deformation due to the high relative measurement errors. We conclude that both GPS and stress data are required to constrain model results.
    Description: This research was supported by the Italian Presidenza del Consiglio dei Ministri - Dipartimento della Protezione Civile (DPC) through the INGV-DPC project S1.
    Description: Published
    Description: 193-204
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Description: open
    Keywords: Neotectonics ; Borehole-breakouts ; Southern Apennines ; Finite-element models ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.08. Theory and Models ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Magnetic fabric of Plio-Pleistocene sediments from the Crotone fore-arc basin: Insights on the recent tectonic evolution of the Calabrian Arc (Italy) (2014)
    Elsevier
    Details
    Publication Date: 2020-12-07
    Description: Low-field anisotropy of magnetic susceptibility (AMS) analyses were performed on 532 samples col-lected in 36 (mostly lower Pliocene to lower Pleistocene) marine clay sites from the Crotone basin, afore-arc basin located on top of the external Calabrian accretionary wedge. The Crotone basin formedsince mid-late Miocene under a predominant extensional tectonic regime, but it was influenced there-after by complex interactions with NW–SE left-lateral strike-faults bounding the basin, which also yieldedpost-1.2 Ma ~30◦counterclockwise block rotations. The basin is filled by continental to marine sedimentsyielding one of the thickest and best-exposed Neogene succession available worldwide. The deep-marinefacies – represented by blue-grey marly clays gave the best results, as they both preserved a clear mag-netic fabric, and provided accurate chronology based on previously published magnetostratigraphy andcalcareous plankton (i.e. foraminifers and nannofossils) biostratigraphy. Magnetic susceptibility rangeand rock magnetic analyses both indicate that AMS reflects paramagnetic clay matrix crystal arrange-ment. The fabric is predominantly oblate to triaxial, the anisotropy degree low (〈1.06), and the magneticfoliation mostly subparallel to bedding. Magnetic lineation is defined in 30 out of 36 sites (where thee12 angle is 〈35◦). By also considering local structural analysis data, we find that magnetic fabric wasgenerally acquired during the first tectonic phases occurring after sediment deposition, thus validatingits use as temporally dependent strain proxy. Although most of the magnetic lineations trend NW–SE andare orthogonal to normal faults (as observed elsewhere in Calabria), few NE–SW compressive lineationsshow that the Neogene extensional regime of the Crotone basin was punctuated by compressive episodes.Finally, compressive lineations (prolate magnetic fabric) documented along the strike-slip fault boundingthe basin to the south support the significance of Pleistocene strike-slip tectonics. Thus the Crotone basinshows a markedly different tectonics with respect to other internal and western basins of Calabria, asit yields a magnetic fabric still dominated by extensional tectonics but also revealing arc-normal short-ening episodes and recent strike-slip fault activity. The tectonics documented in the Crotone basin iscompatible with a continuous upper crustal structural reorganization occurring during the SE-migrationof the Calabria terrane above the Ionian subduction system.
    Description: Published
    Description: 67-79
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Calabrian Arc, Anisotropy of magnetic susceptibility, Structural analysis, Fore-arc region ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Cyanobacteria in Scandinavian coastal waters — A potential source for biofuels and fatty acids? (2014)
    Elsevier
    In:  EPIC3Algal Research, Elsevier, 5, pp. 42-51, ISSN: 2211-9264
    Details
    Publication Date: 2014-06-24
    Description: Since land-based biofuel production competes with conventional food production, a water-based biomass and biofuel production from cyanobacteria offers large potential. This study investigates the application potential of cyanobacteria for fuel production and by-products by mimicking nutrient depleted environmental conditions. Three Baltic cyanobacteria strains (Aphanizomenon flos-aquae, Dolichospermum lemmermannii and Nodularia spumigena) were inoculated in full nutrient levels, as well as phosphorus and nitrogen depleted medium, before being monitored for 14 days. For screening reasons, multiple parameters such as fatty acids, photosynthetic pigments including phycobilins, biovolume, photosynthetic activity, inorganic nutrients, particulate organic carbon, nitrogen and phosphorous were investigated every seven days. We observed a strong negative relationship between lipid content, growth and nutrient availability, resulting in high lipid and pigment production in combination with a limited growth rate in nutrient depleted treatments. Our results suggest that cultivation and harvest of bloom-forming cyanobacteria for fuel and by-product production are feasible in Scandinavia, but strongly depends on the desired compounds and biomass. Each cyanobacteria species originally has a species-specific chemical fingerprint that may be modified by rearing conditions and harvesting period to meet the needs of the consumer. This leads to important conclusions regarding future culturing conditions and biomass production of the desired compounds.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 9
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    Biological validation of physical coastal waters classification along the NE Atlantic region based on rocky macroalgae distribution (2014)
    Elsevier
    In:  EPIC3Estuarine, Coastal and Shelf Science, Elsevier, 147, pp. 103-112, ISSN: 0272-7714
    Details
    Publication Date: 2014-06-30
    Description: A methodology to classify rocky shores along the North East Atlantic (NEA) region was developed. Previously, biotypes and the variability of environmental conditions within these were recognized based on abiotic data. A biological validation was required in order to support the ecological meaning of the physical typologies obtained. A database of intertidal macroalgae species occurring in the coastal area between Norway and the South Iberian Peninsula was generated. Semi-quantitative abundance data of the most representative macroalgal taxa were collected in three levels: common, rare or absent. Ordination and classification multivariate analyses revealed a clear latitudinal gradient in the distribution of macroalgae species resulting in two distinct groups: one northern and one southern group, separated at the coast of Brittany (France). In general, the results based on biological data coincided with the results based on physical characteristics. The ecological meaning of the coastal waters classification at a broad scale shown in this work demonstrates that it can be valuable as a practical tool for conservation and management purposes.
    Repository Name: EPIC Alfred Wegener Institut
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  • 10
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    Neodymium and hafnium boundary contributions to seawater along the West Antarctic continental margin (2014)
    Elsevier
    In:  EPIC3Earth and Planetary Science Letters, Elsevier, 394, pp. 99-110, ISSN: 0012-821X
    Details
    Publication Date: 2018-08-10
    Description: Neodymium and hafnium isotopes and elemental concentrations (Sm, Nd, Hf, Zr) have been measured in three water column profiles south of the Antarctic Circumpolar Current in, and to the east of the Ross Sea, in conjunction with five bottom water samples from the Amundsen Sea Embayment. Neodymium and hafnium both appear to be released from sediments in the Embayment. In the case of Nd, this is reflected in radiogenic isotope compositions (εNd up to −5.4) and highly elevated concentrations (up to 41 pmol/kg). Hafnium isotopes, on the other hand, are only very slightly altered relative to the open ocean sites, and boundary release is most prominently indicated by elevated concentrations (〉1 pmol/kg versus ∼0.7 pmol/kg). There is also a local input of both Hf and Nd at the Marie Byrd Seamounts, which leads to Nd isotope compositions as radiogenic as −3.1, and hafnium shifted to less radiogenic compositions in local bottom water. A compilation of the new data with literature data reveals a consistent view of the influence of Antarctica on the Nd isotope composition in Lower Circumpolar Deep Water (LCDW) and Antarctic Bottom Water (AABW). Sector specific Nd addition shifts AABW formed in the Atlantic sector to less radiogenic isotope compositions (average εNd = −9) relative to LCDW (average εNd = −8.4), whereas AABW in the Pacific sector is shifted to more radiogenic values (average εNd = −7). The evolution towards more radiogenic εNd with depth in LCDW in the Pacific sector is likely to reflect admixture of AABW but, in addition, is also controlled by boundary exchange with the slope as observed at the Marie Byrd Seamounts. Hafnium isotopes are relatively homogeneous in the data set, ranging between εHf = +2 and +3.8 for most samples, excluding less radiogenic compositions in deep waters close to the Marie Byrd Seamounts. The Hf isotope composition in the Pacific sector is, however, slightly less radiogenic than in the Atlantic, corresponding to an average of +3 relative to an average of +3.8. This probably reflects unradiogenic Hf inputs from Antarctica to the Pacific sector, which are vertically homogenized by reversible scavenging. The Hf isotope heterogeneity in LCDW between both sectors is likely to indicate a shorter seawater residence time for Hf than for Nd, which is consistent with the dissolved – particulate phase partitioning of both elements
    Repository Name: EPIC Alfred Wegener Institut
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  • 11
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    Insolation and glacial–interglacial control on southwestern African hydroclimate over the past 140000 years (2014)
    Elsevier
    In:  EPIC3Earth and Planetary Science Letters, Elsevier, 398, pp. 1-10, ISSN: 0012-821X
    Details
    Publication Date: 2014-06-27
    Description: The past climate evolution of southwestern Africa is poorly understood and interpretations of past hydrological changes are sometimes The past climate evolution of southwestern Africa is poorly understood and interpretations of past hydrological changes are sometimes contradictory. Here we present a record of leaf-wax δD and δ13C taken from a marine sediment core at 23°S off the coast of Namibia to reconstruct the hydrology and C3 versus C4 vegetation of southwestern Africa over the last 140 000 years (140 ka). We find lower leaf-wax δD and higher δ13C (more C4 grasses), which we interpret to indicate wetter Southern Hemisphere (SH) summer conditions and increased seasonality, during SH insolation maxima relative to minima and during the last glacial period relative to the Holocene and the last interglacial period. Nonetheless, the dominance of C4 grasses throughout the record indicates that the wet season remained brief and that this region has remained semi-arid. Our data suggest that past precipitation increases were derived from the tropics rather than from the winter westerlies. Comparison with a record from the Congo Basin indicates that hydroclimate in southwestern Africa has evolved in antiphase with that of central Africa over the last 140 ka.
    Repository Name: EPIC Alfred Wegener Institut
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  • 12
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    The Gordian knot of mangrove conservation: Disentangling the role of scale, services and benefits (2014)
    Elsevier
    In:  EPIC3Global Environmental Change, Elsevier, 28, pp. 120-128, ISSN: 0959-3780
    Details
    Publication Date: 2016-10-07
    Description: Mangrove forests are among the most threatened tropical ecosystems. Their role as providers of important ecosystem services such as coastal protection, carbon storage and nursery habitats for economically important species is increasingly acknowledged. But mangrove destruction continues, and we might have to face the prospect of a world deprived of the services offered by mangrove ecosystems. Mangrove transformation and destruction is often caused by mismatches in mangrove system management. These root in interests that focus on selected ecosystem services only, but also result from a problem of fit between the spatial scales at which ecosystem services are provided, and those at which their benefits are realized. We argue that a combination of the ecosystem services concept with a careful approach to the issue of scales will help to overcome these problems and improve the management of mangrove systems. Drawing on two case studies from Indonesia and Brazil, we illustrate the relevance of our findings for different ecosystem services.
    Repository Name: EPIC Alfred Wegener Institut
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  • 13
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    Impact of recirculation on the East Greenland Current in Fram Strait: Results from moored current meter measurements between 1997 and 2009 (2014)
    Elsevier
    In:  EPIC3Deep Sea Research Part I: Oceanographic Research Papers, Elsevier, 92, pp. 26-40, ISSN: 0967-0637
    Details
    Publication Date: 2014-09-09
    Description: Transports of total volume and water masses obtained from a mooring array in the East Greenland Current (EGC) in Fram Strait are presented for the period 1997–2009. The array in the EGC was moved along isobaths from 79°N to 78°50′N78°50′N in 2002 to line up with moorings in the eastern Fram Strait. Analysis of the time series at the two latitudes shows that associated with the southward move, the annual mean volume transport of the EGC increased from 5.8±1.8 Sv to 8.7±2.5 Sv, mostly related with an increase in barotropic flow. This suggests a recirculation of close to 3 Sv at 78°50′N78°50′N as a consequence of the large-scale wind-driven cyclonic gyre in the Nordic Seas. In addition, the volume transport at 78°50′N78°50′N showed a clear seasonal cycle which was absent at 79°N. Estimates of the wind-driven Sverdrup transport at two different latitudes show that the difference in total volume transport and seasonality can largely be explained by the wind-stress curl. However, weak transport in 2003 was only partially related with weak Sverdrup transport and coincided also with anomalously weak northerly winds. The stronger recirculation at 78°50′N78°50′N has also consequences for the observed Atlantic Water: there is significantly more Atlantic derived water present at the southerly latitude. In addition, the warm anomaly in Fram Strait between 2005 and 2007 doubled the amount of Recirculated Atlantic Water temporarily. Finally, we estimate that close to 2.7 Sv, or 50%, of Atlantic derived water recirculates in Fram Strait.
    Repository Name: EPIC Alfred Wegener Institut
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  • 14
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    Biome distribution over the last 22,000 yr in China (2014)
    Elsevier
    In:  EPIC3Palaeogeography, Palaeoclimatology, Palaeoecology, Elsevier, 409, pp. 33-47, ISSN: 0031-0182
    Details
    Publication Date: 2019-08-23
    Description: Patterns of past vegetation changes over time and space can help facilitate better understanding of the interactions among climate, ecosystem, and human impact. Biome changes in China over the last 22,000 yr (calibrated radiocarbon date, a BP) were numerically reconstructed by using a standard approach of pollen-plant functional type-biome assignment (biomization). The biomization procedure involves pollen data from 2434 surface sites and 228 fossil sites with a high quality of pollen count and 14C dating, 51 natural and three anthropogenic plant functional types (PFTs), as well as 19 natural and one anthropogenic biome. Surface pollen-based reconstruction of modern natural biome patterns is in good agreement (74.4%) with actual vegetation distribution in China. However, modern large-scale anthropogenic biome reconstruction has not been successful based on the current setup of three anthropogenic PFTs (plantation, secondary, and disturbed PFT) because of the limitation of non-species level pollen identification and the difficulty in the clear assignment of disturbed PFTs. The non-anthropogenic biome distributions of 44 time slices at 500-year intervals show large-scale discrepant and changed vegetation patterns from the last glacial maximum (LGM) to the Holocene throughout China. From 22 ka BP to 19 ka BP, temperate grassland, xerophytic shrubland, and desert dominated northern China,whereas cold or cool forests flourished in central China.Warm–temperate evergreen forests were restricted to far southern China, and tropical forestswere absent. During 18.5 ka BP to 12 ka BP, cold, cool, and dry biomes extended to someparts of northern,western, and eastern China.Warm–temperate evergreen andmixed forests gradually expanded to occupy thewhole of southern China. A slight northward shift of forest biomes occurred from15 ka BP to 12 ka BP. During 11.5 ka BP to 9 ka BP, temperate grassland and shrubland gradually stretched to northern and western China. Cold and cool forestswidely expanded into northern and central China, aswell as in the northern margin of South China along with temperate deciduous forest. Since the early mid-Holocene (approximately 8.5 ka BP to 5.5 ka BP), all forest biomes shifted northward at the expense of herbaceous and shrubby biomes. Simultaneously, cold and cool forest biomes occupied the marginal areas of the Tibetan Plateau and the high mountains in western China. During the middle to late Holocene, from 5 ka to the present, temperate grassland and xerophytic shrubland expanded to the south and east, whereas temperate deciduous forests slightly shifted southward. After 3 ka BP, forest biomes were absent in western China and on the Tibetan plateau surface. Dramatic biome shifts from theLGM to the Holocene were observed in the forest-grassland ecotone and transitional zones between temperate and subtropical climates, between subtropical and tropical regions, and in the mountainous margins of the eastern Tibetan Plateau. Evidence showed more human disturbances during the late Holocene. More pollen records and historical documents are therefore further needed to understand fully the human disturbance-induced large-scale forest changes. In addition, more classifications of anthropogenic biome or land cover, more distinct assignment of pollen taxa to anthropogenic PFTs, and more effective numerical and/or mechanistic techniques in building large-scale human disturbances are required.
    Repository Name: EPIC Alfred Wegener Institut
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  • 15
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    Dissolved methane concentration and flux in the coastal zone of the Southern California Bight-Mexican sector: Possible influence of wastewater (2014)
    Elsevier
    In:  EPIC3Estuarine, Coastal and Shelf Science, Elsevier, 144, pp. 65-74, ISSN: 0272-7714
    Details
    Publication Date: 2014-07-14
    Description: We measured dissolved methane concentrations ([CH4]) in the coastal zone of the Southern California Bight-Mexican sector (SCBMex) during two cruises: S1 in the USA–Mexico Border Area (BA) during a short rainstorm and S2 in the entire SCBMex during a drier period a few days later. High spatial variability in surface mixed layer (ML) [CH4] was observed, ranging from 2.2 nmol L−1 to 17.8 nmol L−1. ML-[CH4] was supersaturated at all BA stations during both cruises. The highest [CH4] was 72.4 nmol L−1 (2819 % supersaturated) measured at 10 m depth during S2, about 3 km southwest of the discharge point of the South Bay Ocean Outfall (SBOO). Our results show an apparent connection between wastewater treatment discharges and [CH4]. Application of a sewer CH4 production model suggests that the SBOO may be a large source of CH4 to the BA and points to the need to consider point sources in developing coastal marine CH4 budgets for highly populated areas. Based on our data, the SCBMex appears to be a relatively strong source of CH4 to the atmosphere compared to other Pacific Basin areas. The average BA sea-to-air CH4 flux (F) during S1 was (15.5 ± 8.6) × 10−2 nmol m−2 s−1, about 1.5 times higher than F during S2, which had a flux of (9.5 ± 6.9) × 10−2 nmol m−2 s−1 mainly due to the higher wind speed during S1.
    Repository Name: EPIC Alfred Wegener Institut
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  • 16
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    Development of the Western Boundary Undercurrent at Eirik Drift related to changing climate since the early Miocene (2014)
    Elsevier
    In:  EPIC3Deep Sea Research I: Oceanographic Research Papers, Elsevier, 93, pp. 21-34, ISSN: 0967-0637
    Details
    Publication Date: 2019-07-16
    Description: Eirik Drift lies on the slope south of Greenland, where it has been formed under the influence of the Western Boundary Undercurrent (WBUC) closely downstream of its origin in the deep-water formation centres of the Nordic Seas. Therefore, the sediment record at Eirik Drift documents modifications in pathways and intensity of the WBUC. These modifications reflect alterations in deep-water formation in the Nordic Seas and are therefore coupled with climate changes. Based on the seismostratigraphic analysis of sedimentary architecture identified in a set of high-resolution seismic reflection data, we have reconstructed the palaeocirculation of the WBUC at Eirik Drift since the early Miocene. We revealed a strong WBUC during warm climate conditions, and in phases of climate cooling with enhanced sea-ice extent we interpreted weak WBUC influence. We suggest a southward shift of the deep-water formation regions along with a shift of the deep current system during the cool phases. This shift implies that the main North Atlantic deep-water route affected Eirik Drift only during warm phases and that during cool phases weak branches of the circulation system flowed over Eirik Drift.
    Repository Name: EPIC Alfred Wegener Institut
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  • 17
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    The Indian Ocean Zonal Mode over the past millennium in observed and modeled precipitation isotopes (2014)
    Elsevier
    In:  EPIC3Quaternary Science Reviews, Elsevier, 103, pp. 1-18, ISSN: 0277-3791
    Details
    Publication Date: 2014-10-17
    Description: The Indian Ocean Zonal Mode (IOZM) has gained considerable attention in the past decade due to its role in causing widespread flooding and droughts in the continents and islands surrounding the Indian Ocean. The IOZM has also been observed to vary on a low-frequency (multi-decadal) basis, making its behavior important to understand both for mid-range 21st century climate prediction and for paleoclimate studies. Despite efforts to reconstruct the IOZM using corals and other high-resolution proxies, nonstationarities in the response of paleoclimate proxies to the IOZM have also been noted, raising the possibility that the IOZM may be difficult to reconstruct or to predict in the long-term. It is therefore critical to assess the low-frequency component of the IOZM in observed, modeled, and paleoclimate data from the Indian Ocean region in order to identify nonstationary behavior and to assess its role in low-frequency climate variations. We present an analysis of low-frequency and nonstationary behavior in the IOZM on multi-decadal to centennial timescales using a combination of modeled, observed, and proxy reconstructions of δ18O/δDprecip. In order to assess multiple timescales of low-frequency variability, we focus on two key time periods: the historical period (1870–2003), and the past millennium (1000 C.E.-present). We find significant nonstationarities in the relationships between the IOZM, precipitation amount, and δ18Oprecip/δDprecip during the historical period. These relationships vary on a multi-decadal basis in our model and in observed/reanalysis datasets. Air-sea interactions in the Indo-Pacific Warm Pool and teleconnections to the Pacific Ocean, as well as the phase of the IOZM itself, may contribute to this nonstationary behavior. We examine the potential ramifications of nonstationary IOZM behavior using a synthesis of spatially distributed proxy archives of δ18Oprecip/δDprecip from both sides of the IOZM region spanning the past millennium. Our findings indicate that during the past millennium, a strong IOZM-like connection exists in the proxy data network, with anti-correlation between East Africa and Indonesia. However, the links are spatially limited and in some cases timescale-dependent. Nonlinear behaviors in these links suggest that the IOZM may be difficult to detect on a consistent basis in proxy records from the past millennium. Based on our modeling results, the inconsistent links in the IOZM proxy network may arise from temporally and spatially variable relationships between the IOZM, precipitation, and δ18Oprecip/δDprecip. We conclude that the IOZM's potential to influence the climate of the Indian Ocean region is inconsistently reflected in proxy data, and that due to the changing strength of the IOZM/δ18Oprecip/δDprecip relationship, its spatial “footprint” may be restricted on multi-decadal to multi-centennial timescales.
    Repository Name: EPIC Alfred Wegener Institut
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  • 18
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    On the difficulty of modeling Circumpolar Deep Water intrusions onto the Amundsen Sea continental shelf (2014)
    Elsevier
    In:  EPIC3Ocean Modelling, Elsevier, 84, pp. 26-34, ISSN: 1463-5003
    Details
    Publication Date: 2014-11-11
    Description: In the Amundsen Sea, warm Circumpolar Deep Water (CDW) intrudes onto the continental shelf and flows into the ice shelf cavities of the West Antarctic Ice Sheet, resulting in high basal melt rates. However, none of the high resolution global models resolving all the small ice shelves around Antarctica can reproduce a realistic CDW flow onto the Amundsen Sea continental shelf, and previous studies show simulated bottom potential temperature at the Pine Island Ice Shelf front of about −1.8 °C. In this study, using the Finite-Element Sea ice–ice shelf-Ocean Model (FESOM), we reproduce warm CDW intrusions onto the Amundsen Sea continental shelf and realistic melt rates of the ice shelves in West Antarctica. To investigate the importance of horizontal resolution, forcing, horizontal diffusivity, and the effect of grounded icebergs, eight sensitivity experiments are conducted. To simulate the CDW intrusion realistically, a horizontal resolution of about 5 km or smaller is required. The choice of forcing is also important and the cold bias in the NCEP/NCAR reanalysis over the eastern Amundsen Sea prevents warm CDW from intruding onto the continental shelf. On the other hand, the CDW intrusion is not highly sensitive to the strength of horizontal diffusion. The effect of grounded icebergs located off Bear Peninsula is minor, but may act as a buffer to an anomalously cold year.
    Repository Name: EPIC Alfred Wegener Institut
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  • 19
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    Uranium-Thorium Decay Series in the Oceans: Overview (2014)
    Elsevier
    In:  EPIC3Earth Systems and Environmental Sciences, (Reference Module in Earth Systems and Environmental Sciences), Amsterdam, Elsevier, 16 p., pp. 1-16, ISBN: 978-0-12-409548-9
    Details
    Publication Date: 2014-05-19
    Description: Natural radioactivity provides tracers in a wide range of characteristic timescales and reactivities, which can be used as tools to study the rate of reaction and transport processes in the ocean. Apart from cosmogenic nuclides and the long-lived radioisotope K-40, the natural radioactivity in the ocean is primarily derived from the decay series of three radionuclides that were produced in the period of nucleosynthesis preceding the birth of our solar system: Uranium-238, Thorium-232, and Uranium-235 (a fourth series, including Uranium-233, has already decayed away). The remaining activity of these so-called primordial nuclides in the Earth's crust, and the range of half-lives and reactivities of the elements in their decay schemes, control the present distribution of U-series nuclides in the ocean
    Repository Name: EPIC Alfred Wegener Institut
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  • 20
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    A 3D shear-wave velocity model of the upper mantle beneath China and the surrounding areas (2014)
    Elsevier
    In:  EPIC3Tectonophysics, Elsevier, 633, pp. 193-210, ISSN: 0040-1951
    Details
    Publication Date: 2014-12-02
    Description: We present a three-dimensional model of shear wave velocity for the upper mantle of China and the surrounding region by analyzing 50,338 vertical component multi-mode Rayleigh wave seismograms, recorded at 144 permanent and more than 300 temporary broadband stations in and around China. The procedure involves combination of 1-D path average models obtained by modeling each Rayleigh waveform up to the 4th higher mode in a tomographic inversion scheme. The dense station network and the use of multi-mode analysis help to achieve a lateral resolution of a few hundred kilometers down to 400 km depth. The seismic lithosphere, as it is defined by the crust and the high velocity mantle lid, is to the first order thin in east China and thick in the west, with a high velocity lid extending down to about 200 km depth beneath much of the Tibet–Pamir plateau. Beneath India, the thickness of the seismic lithosphere gradually increases from ~ 100 km in south India to more than 150 km in north India, where it underthrusts the Tibetan plateau to approximately the Jinsha River Suture. High velocity lid extending down to 100–150 km depth is also observed in the Tarim basin, Sichuan basin and Ordos block. In the eastern part of the North China craton the seismic lithosphere is probably close to or thinner than 70 km. Adjacent to these areas, the high velocity lid in the eastern Yangtze craton and South China fold system extends down to 70–80 km depth. A large-scale subhorizontal high velocity body is observed at depths of 150–350 km beneath the entire east China cratonic areas. This high velocity body might be the remnant of a delamination process which resulted in the decratonization of the North China and the Yangtze cratons.
    Repository Name: EPIC Alfred Wegener Institut
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  • 21
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    Anomalous South Pacific lithosphere dynamics derived from new total sediment thickness estimates off the West Antarctic margin (2014)
    Elsevier
    In:  EPIC3Global and Planetary Change, Elsevier, 123(Part A), pp. 139-149, ISSN: 0921-8181
    Details
    Publication Date: 2014-12-17
    Description: Paleotopographic models of the West Antarctic margin, which are essential for robust simulations of paleoclimate scenarios, lack information on sediment thickness and geodynamic conditions, resulting in large uncertainties. A new total sediment thickness grid spanning the Ross Sea–Amundsen Sea–Bellingshausen Sea basins is presented and is based on all the available seismic reflection, borehole, and gravity modeling data offshore West Antarctica. This grid was combined with NGDC's global 5 arc minute grid of ocean sediment thickness (Whittaker et al., 2013) and extends the NGDC grid further to the south. Sediment thickness along the West Antarctic margin tends to be 3–4 km larger than previously assumed. The sediment volume in the Bellingshausen, Amundsen, and Ross Sea basins amounts to 3.61, 3.58, and 2.78 million km3, respectively. The residual basement topography of the South Pacific has been revised and the new data show an asymmetric trend over the Pacific–Antarctic Ridge. Values are anomalously high south of the spreading ridge and in the Ross Sea area, where the topography seems to be affected by persistent mantle processes. In contrast, the basement topography offshore Marie Byrd Land cannot be attributed to dynamic topography, but rather to crustal thickening due to intraplate volcanism. Present-day dynamic topography models disagree with the presented revised basement topography of the South Pacific, rendering paleotopographic reconstructions with such a limited dataset still fairly uncertain.
    Repository Name: EPIC Alfred Wegener Institut
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  • 22
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    Cosmogenic 26Al in the atmosphere and the prospect of a 26Al/10Be chronometer to date old ice (2009)
    Elsevier
    In:  EPIC3Earth and Planetary Science Letters, Elsevier, 287, pp. 453-462
    Details
    Publication Date: 2017-10-09
    Description: Cosmogenic radionuclides in the one-million-year half-life range offer unique possibilities for age determinations in geophysics. In measurements where the radioactive decay is being utilized as a clock, uncertainties in age determinations may be reduced if the ratio of two radioisotopes with different half-lives can be used as a chronometer. In this work we investigate the atomic ratio of atmospheric 26Al (t1/2= 0.717 Ma) to 10Be (t1/2=1.386 Ma) measured with accelerator mass spectrometry (AMS), and its potential as a chronometer for dating old ice. The 26Al/10Be ratio decreases with an effective half-life of t1/2(26Al/10Be)= 1.49 Ma. For its application as a chronometer, the atmospheric 26Al/10Be ratio has to be well characterized. However, the properties of atmospheric 26Al have been understood only poorly so far. At the VERA AMS facility of the University of Vienna, a first systematic study of the global variations of the 26Al/10Be ratio in the atmosphere and in surface firn has been carried out, and pilot measurements of the 26Al/10Be ratio in deep Antarctic ice have been performed. Our results indicate that this ratio is globally constant to within 5% in the atmosphere and in surface firn with a mean value of 1.89×10−3. The data also suggest that non-atmospheric sources of 26Al, such as extraterrestrial, in situ produced or re-suspended 26Al, do not contribute significantly to the observed 26Al/10Beratio. In addition, atmospheric mixing seems to exert only aminor influence. In a first application of the method,26Al/10Be ratios were measured in chips collected in connection with the drilling of the lowest part of an ice core (2250 to 2760 m) in Dronning Maud Land,Antarctica. Surprisingly, variable 26Al/10Be ratios ranging between0.5 and up to 2 times the atmospheric ratio were found at different locations in this deep ice core. While the cause for the ratios higher than atmospheric remains unexplained so far, the ratios lower than atmospheric may be caused by radioactive decay, allowing a first dating attempt using the 26Al/10Be ratio. Thus, at an ice depthof 2760 m an approximate date of (6.7±2.6)×105years was established.
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  • 23
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    Carbon dioxide of Pu`u`O`o volcanic plume at Kilauea retrieved by AVIRIS hyperspectral data (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A remote sensing approach permits for the first time the derivation of a map of the carbon dioxide concentration in a volcanic plume. The airborne imaging remote sensing overcomes the typical difficulties associated with the ground measurements and permits rapid and large views of the volcanic processes together with the measurements of volatile components exolving from craters. Hyperspectral images in the infrared range (1900–2100 nm), where carbon dioxide absorption lines are present, have been used. These images were acquired during an airborne campaign by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) over the Pu`u` O`o Vent situated at the Kilauea East Rift zone, Hawaii. Using a radiative transfer model to simulate the measured up-welling spectral radiance and by applying the newly developed mapping technique, the carbon dioxide concentration map of the Pu`u` O`o Vent plume were obtained. The carbon dioxide integrated flux rate were calculated and a mean value of 396±138 t d−1 was obtained. This result is in agreement, within the measurements errors, with those of the ground measurements taken during the airborne campaign.
    Description: Published
    Description: 3192–3199
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: partially_open
    Keywords: Hyperspectral data ; Volcanic plume ; Carbon dioxide ; AVIRIS ; Kilauea ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 24
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    Comparison between the 1994–2006 seismic and gravity data from Mt. Etna: New insight into the long-term behavior of a complex volcano (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We investigate the relationship between changes of the gravity field and the release of the seismic energy at Mt. Etna over a 12-year period (1994-2006), during which the volcano exhibited different eruptive patterns. Over the two sub-periods when intense gravity decreases occur, centered on the upper southeastern sector of the volcano (late-1996 to mid-1999 and late-2000 to mid-2001), the strain release curve displays neat long-term accelerations, with many hypocenters clustered in the volume containing the gravity source. Various evidences suggest that, since 1994 and until the breakout of the 2001 eruption, the eastern flank of Etna remained peripheral to the lines of rise of the magma from the deep storage to the surface. Accordingly, we hypothesize that, rather than being directly associated to the migration of the magma, the joint anomalies we found image phases of higher tensile stress on the upper southeastern sector, associated to increase in the rate of microfracturing along the NNW-SSE fracture zone. Such an increase implies a local density (gravity) decrease, and an increase in the release of seismic energy, thus explaining the correlation we observe. The second period of gravity decrease/strain release increase culminated in the breakout of the 2001 flank eruption, as a pressurized deeper magma accumulation used the inferred zone of increasing microfracturing as a path to the surface. This eruption marks an important modification in the structure of Etna’s plumbing system, as also testified by the absence of post-2001 long-term gravity changes and accelerations in the strain release curve and the neat modification of the seismicity and ground deformation patterns. Thus we prove that joint microgravity and seismic studies can allow zones of the medium experiencing an increase in the rate of microfracturing to be identified months to years before a magma batch is conveyed through them to the surface, setting off a lateral eruption.
    Description: Published
    Description: 282–292
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: microgravity changes ; seismic strain release ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 25
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    A model for Ischia hydrothermal system: Evidences from the chemistry of thermal groundwaters (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Ischia volcano, in Central Italy, has long been known for its copious surface hydrothermal manifestations, signs of a pervasive circulation of hot fluids in the subsurface. Because of the significant chemical heterogeneity of fumarolic gas discharges and hot spring discharges, evidences of a complex hydrothermal setting, a definite model of fluid circulation at depth is currently unavailable, in spite of the several previous efforts. Here, we report on the chemical and isotopic composition of 120 groundwater samples, collected during several sampling surveys from 2002 to 2007. The acquired data suggest that the composition of surface manifestations reflect contributions from meteoric water, sea water, and thermal fluids rising from two distinct hydrothermal reservoir, with equilibrium temperatures of respectively ~150 °C and ~270 °C, and depths of 150–300 m and N300 m (but possibly N1000 m). We also make use of an isotopic characterization of the dissolved gas phase in thermal waters to demonstrate that the Ischia hydrothermal system is currently supplied by a deep-rising gas component (DGC), characterized by CO2 ~97.7±1.2 vol.% (on a water-free basis), δ13CCO2=−3.51±0.9‰, and helium isotopic ratio of about 3.5 Ra (3He/4He ratio normalized to the air ratio, Ra), likely magmatic in origin. An assessment of the thermal budget for Ischia hydrothermal system is also presented, in the attempt to derive a first estimate of the size and rate of degassing of the magmatic reservoir feeding the gas emissions. We calculate that a heat flow of about 153–222 MW presently drives hydrothermal circulation on the island, which we suggest is supplied in convective form (e.g., by the ascent of a high-T magmatic vapour phase) by complete degassing of 2.2–3.3 107 m3 yr−1 of trachytic magma (with ~2.1 wt.% dissolved H2O content). If extrapolated to entire period of quiescence lasting since the Arso eruption in 1302 A.D., this volume corresponds to 1.6–2.3 1010 m3 of magma degassed in about 700 years of quiescent activity.
    Description: Published
    Description: 133–159
    Description: JCR Journal
    Description: reserved
    Keywords: Ischia ; hydrothermal systems ; thermal groudwaters ; thermal and volatile budget ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics
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  • 26
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    Mercury concentration, speciation and budget in volcanic aquifers: Italy and Guadeloupe (Lesser Antilles) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Quantifying the contribution of volcanism to global mercury (Hg) emissions is important to understand the pathways and the mechanisms of Hg cycling through the Earth's geochemical reservoirs and to assess its environmental impacts. While previous studies have suggested that degassing volcanoes might contribute importantly to the atmospheric budget of mercury, little is known about the amount and behaviour of Hg in volcanic aquifers. Here we report on detailed investigations of both the content and the speciation of mercury in aquifers of active volcanoes in Italy and Guadeloupe Island (Lesser Antilles). In the studied groundwaters, total Hg (THg) concentrations range from 10 to 500 ng/l and are lower than the 1000 ng/l threshold value for human health protection fixed by the World Health Organization [WHO (1993): WHO Guidelines for Drinking Water Quality- http://www.who.int/water_sanitation_health/GDWQ/index.htlm]. Positive co-variations of (THg) with sulphate indicate that Hg-SO4-rich acid groundwaters receive a direct input of magmatic/hydrothermal gases carrying mercury as Hg0 (gas). Increasing THg in a volcanic aquifer could thus be a sensitive tracer of magmatic gas input prior to an eruption. Since the complex behaviour and toxicity of mercury in waters depend on its chemical speciation, we carefully determined the different aqueous forms of this element in our samples.We find that dissolved elemental Hg0 (aq) and particulate-bound Hg (HgP) widely prevail in volcanic aquifers, in proportions that highlight the efficiency of Hg adsorption onto colloidal particles. Moreover, we observe that dissolved Hg0 aq and Hg(II) forms coexist in comparable amount in most of the waters, in stark contrast to the results of thermodynamic equilibrium modelling. Therefore, chemical equilibrium between dissolved mercury species in volcanic waters is either prevented by natural kinetic effects or not preserved in collected waters due to sampling/storage artefacts. Finally, we provide a first quantitative comparison of the relative intensity of aqueous transport and atmospheric emissions of mercury at Mount Etna, a very active basaltic volcano.
    Description: Published
    Description: 96-106
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: speciation ; volcanic aquifers ; total and dissolved mercury ; mercury cycling ; volatile budget ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
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  • 27
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    Helium and carbon isotopes in the dissolved gases of Friuli Region (NE Italy): Geochemical evidence of CO2 production and degassing over a seismically active area (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The first geochemical data showing the existence of an active degassing activity over a large seismically active sector of the Southern Alps (Friuli Region, NE Italy) are presented. The dissolved gases, helium and carbon isotopic systematics of 46 water samples taken from 13 sites running along E–W and NE–SW faults besides the natural degassing of a 5000 km2 wide area are investigated. The chemical composition of the dissolved gases revealed that a CO2-rich gas phase feeds the local groundwaters. 3He/4He ratios (R) normalized to the atmospheric 3He/4He ratio (Ra=1.39×10−6) and corrected for the atmospheric contamination (R/Rac), range from 0.29 to 1 as a result of a two component (radiogenic and atmospheric) mixing. The δ13C values of total dissolved inorganic carbon (TDIC) ranging from −15.28 to −0.75‰ vs. PDB, show the occurrence of multiple gas–water interactions. The mixing between the atmospheric air and a crustal source and the gas–water interactions occurring at various extents appears to be the main control on the observed He–C systematics. The natural CO2 degassing was evaluated by a soil gas survey carried out by a grid of about 100 measuring sites located over the area that generated destructive seismic sequences (e.g. the Gemona sequence of 1976; main shocks M6.4 of 6th May and M6.1 of 11th and 15th September). The results obtained show that a significant amount of crustal-originated gases are released over the continental area of Eastern Southern Alps. The evidence that carbon dioxide is associated with radiogenic-type helium denotes the lack of the mantle as primary energy and degassing source, highlighting the possibility that CO2 is produced by thermo-mechanical processes occurring at seismogenic depth. The information provided here may be used to start up a long-term geochemical monitoring of this seismically active area and could be able to detect the modifications occurring to the circulating fluids to gain a better insight on the relationships between the fluids' geochemistry and the activity of the local seismogenic faults.
    Description: Published
    Description: 76–85
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Fluids ; Faults ; geochemistry ; isotopes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 28
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    Pleistocene magnetochronology of early hominin sites at Ceprano and Fontana Ranuccio, Italy (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Paleomagnetic analyses were conducted on two cores drilled at Ceprano in central Italy where an incomplete hominin cranium was discovered in1994, as well as on two additional cores from the nearby site of Fontana Ranuccio that yielded hominin remains associated with an Acheulean industry. No evidence for the 0.78 Ma Brunhes–Matuyama boundary was found at Ceprano down to 45 m below the level that yielded the hominin cranium. The Ceprano lithostratigraphy and the paleomagnetic age constraints are broadly consistent with the stratigraphy of the Liri lacustrine sequence of the Latina Valley, constrained by published K–Ar ages between ~0.6 and ~0.35Ma, and according to an age model with magnetic susceptibility supported by pollen facies data, suggest that the level that yielded the hominin cranium has an age of ~0.45 (+0.05, −0.10) Ma. Evidence for the Brunhes–Matuyama boundary was found at Fontana Ranuccio about 40 m below the hominin level, consistent with a K–Ar age of ~0.46 Ma reported for this level. Hence the Ceprano and Fontana Ranuccio hominin occurrences may be of very similar mid-Brunhes age.
    Description: Published
    Description: 255-268
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Pleistocene ; Ceprano ; Fontana Ranuccio ; magnetostratigraphy ; hominins ; Italy ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
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  • 29
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    Mercury gas emissions from La Soufrière Volcano, Guadeloupe Island (Lesser Antilles) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Quantifying mercury (Hg) emissions from active volcanoes is of particular interest for better constraining the global cycle and environmental impact of this highly toxic element. Here we report on the abundance of total gaseous (TGM=Hg0 (g)+HgII (g)) and particulate (Hg(p)) mercury in the summit gas emissions of La Soufrière andesitic volcano (Guadeloupe island, Lesser Antilles), where enhanced degassing of mixed hydrothermalmagmatic volatiles has been occurring since 1992 from the Southern summit crater.We demonstrate that Hg in volcanic plume occurs predominantly as gaseous mercury, with a mean TGM/Hg(p) mass ratio of ~63. Combining the mean TGM/H2S mass ratio of the volcanic plume (~3.2×10−6), measured close to the source vent, with the H2S plume flux (~0.7 t d−1), determined simultaneously, allows us to estimate a gaseous mercury emission rate of 0.8 kg yr−1 from La Soufrière summit dome. Somewhat lower TGM/Stot mass ratio in fumarolic gases from the source vent (4.4×10−7) suggests that plume chemical composition is not well represented by the emission source (fumaroles) due to chemical processes prior to (or upon) discharge. Current mercury emission from La Soufrìere volcano represents a very small contribution to the estimated global volcanic budget for this element.
    Description: Published
    Description: 276-282
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Mercury ; Fumaroles ; Volcanic plume ; Trace metals ; Gaseous and particulate mercury ; Emission rate ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 30
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    Pre-existing cross-structures and active fault segmentation in the northern-central Apennines (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The multideformed axial zone of the Apennines provides a great opportunity to explore the influence of preexisting cross-structures (inherited from pre-Quaternary tectonic phases) on the segmentation of Quaternary/active seismogenic extensional faults. Detailed geological and structural data and their comparison with seismological data show that although the attitudes (strike and dip) of oblique preexisting faults are certainly an important factor in determining a segment boundary, the size of the inherited oblique structures seems to be more crucial. Pre-existing cross-structures with lengths ranging from several kilometers to a few tens of kilometers show a twofold behavior. They can act as segment barriers during the rupture of a single fault segment or they can be reactivated as transfer zones inducing the activation of two adjacent segments that belong to the same fault system. Regional basement/crustal oblique pre-existing cross-structures, with lengths ranging from several tens of kilometers to hundreds of kilometers (commonly NNE-striking), may act as “persistent structural barriers” that halt both fault segment and fault system propagation, thus determining their terminations and maximum sizes. In the northern-central Apennines, the NNE-striking Ancona–Anzio, Valnerina, and Ortona–Roccamonfina tectonic lineaments, although having been repeatedly reactivated since the Mesozoic, represent the most important examples of these structures. Moreover, probably due to their misorientation with respect to the present extensional stress field, regional NNE-striking pre-existing structures appear to be less likely to produce strong magnitude events (no surface evidence for Quaternary faulting has been found thus far and historical and instrumental seismicity shows only Mb6 events). M ~7 event, on the other hand, is more likely to occur along the (N)NW–(S)SE trending normal fault systems. Lastly, we propose a model that can explain the different sizes of fault segments and fault systems on the basis of their location with respect to the “persistent structural barriers” and their spacing. In this view, our results may contribute to a more reasonable assessment of the nature and size of future surface ruptures in the northern-central Apennines, which are of critical importance to estimating seismic hazard.
    Description: Published
    Description: 304-319
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Active faults ; Segmentation ; Pre-existing cross-structure ; Structural barrier ; Northern/central Apennines ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
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  • 31
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    Insight on recent Stromboli eruption inferred from terrestrial and satellite ground deformation measurements (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The multi-parametric permanent system (tilt and GPS networks, robotized geodetic station) for monitoring ground deformation at Stromboli volcano was set up in the 1990s and later greatly improved during the effusive event of 2002–2003. Unlike other volcanoes, e.g. Mt. Etna, the magnitude of ground deformation signals of Stromboli is very small and through the entire period of operation of the monitoring system, only two major episodes of deformation, in 1994–1995 and 2000, which did not lead to an eruption but rather pure intrusion, were measured. Similarly to the 2002–2003 eruption, no important deformations were detected in the months before the 2007 eruption. However, unlike the 2002–2003 eruption, GPS and tilt stations recorded a continuous deflation during the entire 2007 eruption, which allowed us to infer a vertical elongated prolate ellipsoidal source, centered below the summit craters at depth of about 2.8 km b.s.l. Due to its geometry and position, this source simulates an elongated plumbing system connecting the deeper LP magma storage (depth from 5 to 10 km) with the HP shallower storage (0.8–3 km), both previously identified by petrologic and geochemical studies. This result represents the first contribution of geophysics to the definition of the plumbing system of Stromboli at intermediate depth. Finally, no deformation due to the plumbing system was measured for a long time after the end of the eruption. Meanwhile, the new terrestrial geodetic monitoring system installed within the Sciara del Fuoco, on the lava fan formed during the eruption, indicated that during the first months after the end of the eruption the ground velocity progressively decreased in time, suggesting that part of the deformation was due to the thermal contraction of the lava flow.
    Description: Published
    Description: 172-181
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; Ground Deformation ; source modelling ; flank instability ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 32
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    Halogens in volcanic systems (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The transport, degassing and atmospheric release of halogens from active volcanism on Earth have been the focus of increasing interest over the last few decades, and have recently been the subject of the 1st workshop on “Halogens in volcanic systems and their environmental impacts” that was held in December of 2007 at Yosemite Lodge in Yosemite National Park, California. As an introduction to this Chemical Geology special issue, collecting contributions from many of the participants at the workshop, we review here recent advances in this field, including experimental and theoretical investigations of halogen behaviour in volcanic and related magmatic systems. We discuss previous research on several aspects of halogen geochemistry, including halogen abundances in the mantle and magmas on Earth; the effects of halogens on phase equilibria and melt viscosities; their partitioning between melt and fluid phase(s) upon decompression, cooling and crystallisation of magmas in the Earth's crust; and their final atmospheric release as volcanic gases. The role of halogens in the genesis of hydrothermal systems and in the transport of ore-forming metals is also reviewed, and we discuss our current understanding of atmospheric processing of volcanic halogens in both the troposphere and stratosphere, and their consequent impacts. In spite of these recent advancements, our current understanding of halogen geochemistry at active volcanoes is still far too fragmentary, and the key questions that require answers from future research are summarised in our conclusions.
    Description: Published
    Description: 1-18
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Halogens ; Magmatic fluids ; Ore deposits ; Volcanic degassing ; Volcanic gas ; Atmospheric effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 33
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    Degassing of halogens from basaltic volcanism: Insights from volcanic gas observations (2009)
    Elsevier
    Details
    Publication Date: 2017-04-03
    Description: The currently available data set of S–Cl–F abundances in volcanic gas plumes and high-temperature fumarolic gas samples from basaltic volcanism is reviewed here in the attempt to derive constraints on the modes of halogen degassing from mafic silicate melts. Apart from large volcano-to-volcano variations, reflecting remarkable differences in volatile abundances in the source magmas, each of the explored volcanoes displays large changes of SO2/HCl and SO2/HF ratios with the style of volcanic activity, with HCl/HF staying fairly constant. Halogen abundances are low and SO2/HCl and SO2/HF are high when fresh (volatile-rich) magmas sustain degassing, as during explosive eruptions, at the onset of eruptive cycles, or shortly before paroxysmal events. Low SO2/HCl and SO2/HF ratios are instead characteristic of late stages of volcanic degassing, typically being observed in the concluding stages of basaltic eruptions, or during periods of reduced magma supply at persistently degassing volcanoes. These observations are taken as evidence of halogens being less keen to enter the gas phase (relative to S) during degassing of basaltic magmas; and quantitatively interpreted in light of a Rayleigh-type open-system degassing model. The model, though simple, quantitatively reproduces the range of volcanic gas compositions observed at basaltic volcanoes worldwide, and allows prediction of vapour/melt partitioning contrasts of factors ~9 and ~36 for the volatile couples S–Cl and S–F, respectively. These predictions require validation from appropriately designed experiments of halogen partitioning between magmatic vapours and silicate melts over a range of P–T–X conditions.
    Description: Published
    Description: 99-109
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcanic degassing ; Halogens ; Volcanic gases ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 34
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    Fault plane orientation of microearthquakes at Mt. etna from the inversion of P-wave rise times (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: crucial point in the analysis of tectonic earthquakes occurring in a volcanic area is the inference of the orientation of the structures along which the ruptures occur. These structures represent zones of weakness which could favor the migration of melt toward the surface and the assessment of their geometry is a fundamental step toward efficient evaluation of volcanic risk. We analyzed a high-quality dataset of 171 low-magnitude, tectonic earthquakes occurred at Mt. Etna during the 2002-2003 eruption. We applied a recently developed technique aimed at inferring the source parameters (source size, dip and strike fault) and the intrinsic quality factor Qp of P waves from the inversion of rise times. The technique is based on numerically calibrated relationships among the rise time of first P waves and the source parameters for a circular crack rupturing at a constant velocity. For the most of the events the directivity source effect did not allow us to constrain the fault plane orientation. For a subset of 45 events with well constrained focal mechanisms we were able to constrain the “true” fault plane orientation. The level of resolution of the fault planes was assessed through a non linear analysis based on the random deviates technique. The significance of the retrieved fault plane solutions and the fit of the assumed source model to data was assessed through a χ-square test. Most of the retrieved fault plane solutions agree with the geometrical trend of known surface faults. The inferred source parameters and Qp are in agreement with the results of previous studies.
    Description: In press
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: rise time ; Mt. Etna ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods
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  • 35
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    The effects of volcanic eruptions on atmospheric chemistry (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Volcanoes are very strong sources of sulphur, acids and other gases, as well as particles, that are of atmospheric relevance. Some gases only behave as passive tracers, others affect the formation, growth or chemical characteristics of aerosol particles and many lead to adverse effects on vegetation and human health when deposited in the vicinity of volcanoes. In this article the main effects of volcanic emissions on atmospheric chemistry are discussed, with a focus on sulphur and halogen compounds, and to a smaller extent on climate. We primarily focus on quiescent degassing but the main effects of explosive eruptions on the troposphere and stratosphere are covered as well. The key distinction between chemistry in magmatic and hydrothermal settings and the atmosphere is that the atmosphere is oxidising whereas the chemistry is typically reducing in the former cases due to very low oxygen concentrations. Rapid catalytic cycles involving radicals are a further characteristic of atmospheric chemistry. Most reaction cycles involve the photolysis of molecules as a key part of the reaction chains. Recent measurements of halogen radicals in volcanic plumes showed that volcanic plumes are chemically very active. We explain the formation mechanism of halogen oxides in plumes as well as their relevance for the atmosphere.
    Description: Published
    Description: 131-142
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Quiescent degassing ; Troposphere ; Halogens ; Atmospheric chemistry ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects
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  • 36
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    The evolution of the Sciara del Fuoco subaerial slope during the 2007 Stromboli eruption: Relation between deformation processes and effusive activity (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Focusing on the Island of Stromboli, this research investigates whether airborne remote sensing systems, such as those based on digital photogrammetry and laser scanner sensors, can be adopted to monitor slope deformation and lava emplacement processes in active volcanic areas. Thanks to the capability of extracting accurate topographic data and working on flexible time schedules, these methods can be used to constrain the regular and more frequent measurements derived from satellite observations. This work is dedicated to the monitoring of Stromboli's volcanic edifice which is beneficial when obtaining quantitative data on the geometry of deformation features and the displaced (failures and landslides) and emplaced (lava flows) volumes. In particular, we focus on the capability of extracting average effusion rates from volume measurements that can be used to validate or integrate satellite-derived estimates. Since 2001, a number of airborne remote sensing surveys, namely Digital Photogrammetry (DP) and Airborne Laser Scanning (ALS), have been carried out on Stromboli's volcano to obtain high resolution Digital Elevation Models (DEM) and orthophotos with sub-meter spatial resolution and a time schedule suitable for monitoring the morphological evolution of the surface during the quiescent phases. During the last two effusive eruptions (2002–2003 and 2007) the surface modifications, created on the Sciara del Fuoco slope and on the crater area as a consequence of effusive activity, were quantified and monitored using the same methodologies. This work, which is based on the results obtained from the multi-temporal quantitative analysis of the data collected from 2001 to 2007, mainly focuses on the 2007 eruption but also accounts for analogies and differences regarding the 2002–2003 event. The 2007 eruption on the Sciara del Fuoco slope from 27 February until 2 April, produced a compound lava field including a lava delta on the shoreline, discharging most of the lava into the sea. The comparison of the 2007 DEMs with a pre-eruption surface (2006 LIDAR survey) allowed for the evaluation of the total lava volume that accumulated on the subaerial slope while two syn-eruption DEMs were used to calculate the average effusion rates during the eruption. Since the evolution of a lava field produced during an eruption can be seen as a proxy for the magma intrusion mechanism, hypotheses are formulated on the connection between the lava discharge and the instabilities suffered by the slope.
    Description: Published
    Description: 201-213
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Slope deformation ; Effusive activity ; Aerial surveys ; Digital elevation model ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 37
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    Hazards from pyroclastic density currents at Mt. Etna (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-03
    Description: Despite the recent recognition of Mount Etna as a periodically violently explosive volcano, the hazards from various types of pyroclastic density currents (PDCs) have until now received virtually no attention at this volcano. Large-scale pyroclastic flows last occurred during the caldera-forming Ellittico eruptions, 15–16 ka ago, and the risk of them occurring in the near future is negligible. However, minor PDCs can affect much of the summit area and portions of the upper flanks of the volcano. During the past ~ 20 years, small pyroclastic flows or base-surge-like vapor and ash clouds have occurred in at least 8 cases during summit eruptions of Etna. Four different mechanisms of PDC generation have been identified during these events: (1) collapse of pyroclastic fountains (as in 2000 and possibly in 1986); (2) phreatomagmatic explosions resulting from mixing of lava with wet rock (2006); (3) phreatomagmatic explosions resulting from mixing of lava with thick snow (2007); (4) disintegration of the unstable flanks of a lava dome-like structure growing over the rim of one of the summit craters (1999). All of these recent PDCs were of a rather minor extent (maximum runout lengths were about 1.5 km in November 2006 and March 2007) and thus they represented no threat for populated areas and human property around the volcano. Yet, events of this type pose a significant threat to the lives of people visiting the summit area of Etna, and areas in a radius of 2 km from the summit craters should be off-limits anytime an event capable of producing similar PDCs occurs. The most likely source of further PDCs in the near future is the Southeast Crater, the youngest, most active and most unstable of the four summit craters of Etna, where 6 of the 8 documented recent PDCs originated. It is likely that similar hazards exist in a number of volcanic settings elsewhere, especially at snow- or glacier-covered volcanoes and on volcano slopes strongly affected by hydrothermal alteration.
    Description: Published
    Description: 148-160
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Pyroclastic density currents ; Mt. Etna ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 38
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    Chronology of the 2007 eruption of Stromboli and the activity of the Scientific Synthesis Group (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On 27 February 2007, at 12.49 GMT, a new eruption of Stromboli took place with the effusion of a lava flow from a fracture cutting the flank of the NE cone, which rapidly reached the sea. The eruption had been heralded by an increase in the amplitude of tremor and flank movement since at least the 14th of February. Short-term precursors were an increase in the rate of occurrence of small landslides within the “Sciara del Fuoco” scar on the North-western flank of the volcano. A new effusive vent opened at 18.30 GMT on the Sciara del Fuoco at an height of 400 m asl. The new lava emission caused the sudden termination of the summit flow and initiated a period of non-stationary lava outpouring which ended on 2 April, 2007. The eruption has been characterized by a rapid decrease in the eruption rate after the first days and subsequently by episodic pulse increases. On the 15th of March, the increase in lava outpouring, monitored by a thermal camera, heralded by 9 min the occurrence of a violent paroxysmal explosion with the formation of an impulsive eruption column and the emission of small pumices mingled with black scoriae. The pumice had a bulk composition similar to that of the lava and of the black scoriae, but with a distinct lower content of phenocrysts. A similar feature has been repeatedly observed during the major explosive paroxysms of Stromboli. Short term precursors of the paroxysm were recorded by strainmeter and tiltmeter stations. The volcano monitoring activity has been made by a joint team of researchers from the INGV sections of Catania, Napoli, Palermo and Rome, along with researchers from the Universities of Florence, Pisa, Roma Tre, and Palermo. The scientific activity was coordinated by a Synthesis Group made up by scientists responsible for the different monitoring techniques of INGV and Universities and by the volcanic experts of Commissione Nazionale Grandi Rischi of the Prime Minister Office (Civil Protection Department). The group made a daily evaluation of the state of the volcano and transmitted its recommendations to the Civil Protection Department (DPC). Several prevention measures were adopted by DPC, the main of which were the evacuation of the coast zone when strong acceleration of the Sciara del Fuoco slope motion (occurred twice) could led to a dangerous tsunami by flank collapse (as last occurred on 30 December 2002) and four days before the 15 March paroxysm when access was prohibited to the part of the volcano above 290 m asl.
    Description: Published
    Description: 123–130
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli volcano ; 2007 eruption ; scientific emergency management ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 39
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    Rainwater-induced leaching of selenium, arsenic and vanadium from Etnean volcanic soils (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Active volcanoes emit considerable amounts of contaminants such as As, Se and V. Mount Etna is the biggest volcano of Europe and an excellent geochemical site to study water-soil processes. Due to its volcanic activity, the rainwater has a strong compositional gradient, both in time and space. At present, the behaviour of trace elements in the soils around Mt Etna is poorly understood. To determine the influence of the rainwater pH on the potential mobilization of geogenic pollutants, batch experiments have been performed with synthetic rainwater for 25 soils collected along the flanks of the volcano. Our results show that: i) The maximum concentrations in the leaching solutions are higher for acid rain than for neutral rain (e.g. 7.7 vs 1.3 mg/L for Se). ii) With neutral rain conditions the soils upwind from the volcano have higher concentrations of Se than those downwind (up to 1.3 mg/L compared to ≤0.3 mg/L for the other samples). This trend is less clear for As and V. iii) For soils collected from 2 to 10 km downwind of the craters, Se concentrations in acid rain leachates decrease one order of magnitude with increasing distance. A similar pattern is also observed upwind from the volcano. For As and V no clear relationship between concentrations and location with respect to the volcanic craters is observed. Both i) and ii) result in a low pH dependence for samples upwind from the volcano. The biggest difference between acid and neutral leaching for As and V is observed for a sample 2 km downwind from the craters. The observed patterns are influenced by potential controlling factors, such as organic matter content, total concentrations, mineralogy, influence of the volcanic plume, etc. Our results have implications for the chemical composition of the Etnean aquifer, the only water resource to the one million inhabitants around Mt Etna, as well as for the bioavailability and potential toxicity through agricultural activities, essential to the local economy.
    Description: Published
    Description: Davos, Switzerland
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: open
    Keywords: volcanic soils ; selenium ; arsenic ; vanadium ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 03. Hydrosphere::03.03. Physical::03.03.01. Air/water/earth interactions ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.08. Risk::05.08.01. Environmental risk
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  • 40
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    A seismic sequence from Northern Apennines (Italy) provides new insight on the role of fluids in the active tectonics of accretionary wedges (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We analyze a seismic sequence which occurred in 2000 along the Northern Apennines accretionary wedge (Italy). The sequence developed within the Cretaceous–Triassic limestones of the tectonic wedge, where methane-rich and oil reservoirs are stored. Ruptures mainly developed on WNW–ESE striking thrusts. The compressive stress field is consistent with that acting at regional scale in Northern Apennines. Seismic parameters indicate that fluids are involved in the seismogenic process. The amplitudes of the P and S phases and data from some stations evidence a P to S conversion within Vp/Vs=2.1 layer. The attenuation properties of crust show a higher attenuation zone located west of the epicentral cloud. Eight hundred aftershocks delineate a sub-vertical cloud of events between 7 and 14 km depth. The space–time evolution of the aftershocks is consistent with a diffusive spreading (diffusivity=1.9 m2/s) along vertically superimposed thrusts. Diffusion also controls the time evolution of the sequence. Fluid pressure is estimated to be roughly equal to the vertical, lithostatic stress. The overpressure within reservoirs develops by tectonic compaction processes. The fluids upraise along sub-vertical fractures related to the shortening of the wedge. The 2000 sequence occurred in an area that separates a thermal and deeper petroleum system from a shallower biogenic system. The divider of these systems controls the attenuation properties of the crust. The fluid–rock interaction at seismogenetic depth is related to hydrothermal processes more than to compaction. In accretionary wedges, seismicity activating superimposed thrusts may drive methane and oil upraising from the upper crust.
    Description: Published
    Description: 99-109
    Description: 3.1. Fisica dei terremoti
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: partially_open
    Keywords: seismicity ; fluids ; accretionary wedge ; thrust ; geodynamics ; Northern Apennines ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 41
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    Effects of soil gas permeability and recirculation flux on soil CO2 flux measurements performed using a closed dynamic accumulation chamber (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Dynamic accumulation chamber methods have been extensively used to estimate the total output of CO2 released from active volcanic area. In order to asses the performance and reliability of a closed dynamic system several tests were carried out with different soil permeabilities and soil CO2 fluxes. A special device was used to create a constant one-dimensional CO2 flux through a soil column with a known permeability. Three permeabilities were investigated, ranging between 3.6 × 10− 2 and 3.5 × 10 μm2, as were several CO2 fluxes (ranging between 1.1 × 10− 6 and 6.3 × 10− 5 kg m− 2 s− 1). The results highlight that the accuracy of soil CO2 flux measurements strictly depends on the soil gas permeability and the soil CO2 flux regimen. Generally chamber measurements underestimate CO2 fluxes at low soil permeability and low soil CO2 fluxes, whereas appreciable overestimations occur for high permeability soil, especially for high soil CO2 fluxes. Other tests carried out with different settings for the measurement device, such as the chamber volume and the flux of the pump used to recirculate air through the chamber and the gas analyzer (recirculation flux), revealed a strong dependence of the closed dynamic chamber measurements on the recirculation flux. Low recirculation fluxes (0.2–0.4 l min− 1) decreased the performance of the measurement system, causing underestimations of the actual soil CO2 flux, whereas higher values (0.6–1.0 l min− 1) resulted in overestimations, especially for elevated soil CO2 fluxes. An empirical equation was deduced to allow accumulation chamber fluxes to be calculated very accurately based on soil gas permeabilities measured in the field.
    Description: Published
    Description: 387-393
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: Soil CO2 flux measuraments ; Closed dynamic chamber ; soil gas permeability ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 42
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    Time-dependent deformation of the eastern flank of Mt. Etna: after-slip or viscoelastic relaxation? (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Major results of post-intrusive GPS monitoring of the five months encompassing and following the onset of 2002-03 Mt. Etna eruption are presented and discussed here. The overall ground deformation pattern is characterized by a time-dependent relaxation function. We evaluated two different parameterizations of relaxation functions, each one linked to a different relaxation process: i) viscoelastic relaxation and ii) after-slip mechanism. The former indicated that the process occurred within a weak layer characterized by viscosity values ranging between 7.1 • 1014 Pa s and 1.3 • 1015 Pa s. The latter evidenced that frictional processes occurred beneath a layer of velocity-strengthening having a thickness with values ranging between 0.4 km and 1.7 km. Either model may explain the observed time-dependent deformation, both from the statistical point of view and the comparison with geologic and seismic information. Although we are unable to favour one model rather than the other, these results indicate that the mechanism, responsible for the observed post-intrusive deformation, occurs within a sliding “zone” located inside the clayey sedimentary basement.
    Description: This study was undertaken with financial support from the FLANK project (DPC-INGV 2008 - 2010 contract)
    Description: Published
    Description: 300-311
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: 2002-03 Mt. Etna eruption ; Post-intrusive relaxation ; Viscoelastic ; After-slip ; Rheology ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 43
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    Magma dynamics during the 2007 Stromboli eruption (Aeolian Islands. Italy): mineralogical, geochemical and isotopic data (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: After the 6 month-long effusive event of 2002-2003, a new lava effusion occurred at Stromboli between 27 February and 2 April 2007. Despite the different durations, approximately the same volume of magma was emitted in both eruptions, in the order of 107 m3 . A paroxysmal eruption occurred at the summit craters in both the 2002–2003 and 2007 episodes, during which a significant amount of low porphyritic (LP), volatile- rich magma was erupted. In both cases, the paroxysm did not interrupt the lava emission. Here, we present compositional data, including texture, mineralogy, chemistry and Sr and Nd isotope ratios of bulk-rock, groundmass and separated minerals of lavas erupted in 2007, together with chemistry and Sr and Nd isotope composition of the pumices emitted during the 15 March paroxysm. As a whole, the lavas have the same texture and chemistry that characterize the highly porphyritic (HP) products usually erupted at Stromboli during normal Strombolian activity and effusive events. Compared to the previous HP products, the 2007 lavas show minor but systematic mineralogical and isotopic variations which are consistent with a modest increase of the magma supply rate of the volcano. Compositional variations during the entire duration of the event are very modest. Glass chemistry changes in lavas erupted in the second half of March can be explained by theminormixing between the volatile-rich LPmagma rising through the shallowmagmatic systemduring the 15 March paroxysm and the degassed residing HP magma. A first conclusion of this study is that there is no compositional evidence supporting major changes in the magma dynamics of the volcano accompanying the effusive activity, as also suggested for the 2002–2003 event. The activity of Stromboli is controlled by a steady state feeding system in which refilling, mixing, degassing and crystallization at shallow level continuously operate,withmodest oscillations in themagma supply rate. Switching between normal Strombolian and effusive activity is related to periods of relatively more vigorous refilling of the shallow system, leading to progressive pressure increase in the upper conduits associated with only minor compositional variations in the erupted products.
    Description: Published
    Description: 255–268
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli volcano ; petrological monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
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  • 44
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    Effects of wall-rock elasticity on magma flow in dykes during explosive eruptions (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Magma flow during explosive volcanic eruptions has been described assuming rigid conduits with simple cylindrical or planar geometries. Here we study the dynamics of explosive volcanic flows to take account of the role of elastic deformation of the conduit influenced by local magmatic pressure. Three cases are investigated: a dyke with elliptical cross-section, a cylindrical conduit and a deep dyke connected to a shallow cylinder. The model CPIUC (Macedonio et al., 2005) was used for simulations and generalized to account for elastic deformations of the conduit cross-section area due to magmatic overpressure. Fragmentation level is typically deeper in a dyke than in a cylinder. For flows in wide dykes pressure at the fragmentation depth can be lower than the surrounding lithostatic pressure by several tens of MPa, indicating that the wall-rocks of the dyke will be unstable, constraining the dyke width and eventually blocking the eruption. On the other hand, when the fragmentation level is shallow the corresponding lithostatic pressure is not large enough to close the dyke and eruptions from wide dykes are possible. The behaviour changes drastically when we assume the conduit is a dyke at depth that evolves to a cylinder near the surface. In this case even very wide dykes can be stable because the fragmentation level moves into the cylindrical region where deformation is negligible.
    Description: Published
    Description: 455–462
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: conduit geometry ; explosive eruption ; elastic effect ; dyke deformation ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
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  • 45
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    Integrated stratigraphic reconstruction for the last 80 kyr in a deep sector of the Sardinia Channel (Western Mediterranean) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A quantitative analysis of planktonic foraminifera, coupled with petrophysical and paleomagnetic measurements and 14C AMS calibrations, was carried out on a deep core recovered in the Sardinia Channel (Western Mediterranean Sea), during the CIESM Sub2 survey, providing an integrated stratigraphic time-framework over the last 80 kyr. Significant changes in the quantitative distribution of planktonic foraminifera allowed the identification of several eco-bioevents useful to accurately mark the boundaries of the eco-biozones widely recognised in the Western Mediterranean records and used for large scale correlations. Namely, 10 eco-biozones were identified based on the relative abundance of selected climate sensitive planktonic foraminiferal species. Sixteen codified eco-bioevents were correlated with the Alboran Sea planktonic foraminiferal data and four climatic global events (Sapropel S1, Younger Dryas, Greenland Isotope Interstadial 1, Greenland Isotope Stadial 2, Heinrich event H1-H6) were recognized. The eco-bioevents together with the 14C AMS calibrations concurred to define an accurate age model, spanning between 2 and 83 kyr cal. BP. The reliability of the age model was confirmed by comparing the colour reflectance (550 nm%) data of the studied record with the astronomically tuned one of the Ionian sea (ODP-Site 964). A mean sedimentation rate of about 7 cm/kyr was evaluated including three turbidite event beds that were chronologically constrained within the relative low stand and lowering sea level phases of the MIS 4 and MIS 3. The deep sea sedimentary record includes a distinct tephra occurring at the base of the core which dates 79 ka. The paleomagnetic data provide a well-defined record of the characteristic remanent magnetization that may be used to reconstruct the geomagnetic paleosecular variation for the Mediterranean back to 83 kyr cal. BP.
    Description: In press
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: open
    Keywords: integrated stratigraphy, late Neogene marine record, eco-bio-events, reflectance 550 nm %, Sardinia ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 46
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    Statistical analysis of the Central-Europe Seismicity (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The aim of this paper is to characterize the spatio-temporal distribution of Central-Europe seismicity. Specifically, by using a non-parametric statistical approach, the proportional hazard model, leading to an empirical estimation of the hazard function, we provide some constrains on the time behavior of earthquake generation mechanisms. The results indicate that the most conspic- uous characteristics of MW 4.0+ earthquakes is a temporal clustering lasting a couple of years. This suggests that the probability of occurrence increases immediately after a previous event. After a few years, the process becomes almost time independent. Furthermore, we investigate the cluster properties of the seismicity of Central-Europe, by comparing the obtained result with the one of synthetic catalogs generated by the epidemic type aftershock sequences (ETAS) model, which previously have been successfully applied for short term clustering. Our results indicate that the ETAS is not well suited to describe the seismicity as a whole, while it is able to capture the features of the short- term behaviour. Remarkably, similar results have been previously found for Italy using a higher magnitude threshold.
    Description: In press
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: Earthquake Distribution ; Earthquake Forecast ; Spatio-temporal statistical analysis ; Cluester ; Central Europe ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
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  • 47
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    Methane fluxes from the soils in active volcanic areas: the case of Pantelleria Island (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Methane, the most abundant hydrocarbon in the atmosphere, plays an important role in the Earth’s atmospheric chemistry and radiative balance being the second most important greenhouse gas after CO2. Methane is released to the atmosphere by a wide number of sources, both natural and anthropogenic, with the latter being twice as large as the former (Kvenvolden and Rogers, 2005). It has recently been established that significant amounts of geological methane, produced within the Earth’s crust, are currently released naturally into the atmosphere (Etiope, 2004). Among natural sources the volcanic/geothermal emissions are probably the least constrained. Recent estimations for volcanic and geothermal systems in Europe (Etiope et al. 2007) gave a rather large provisional range (4-16 kt/a) that claims for much more field measurements in order to widen the current database and decrease the present uncertainties. Pantelleria is an active volcanic complex, at present in quiescent status, hosting a high enthalpy geothermal system. Explorative geothermal wells tapped an exploitable water-dominated reservoir at 600-800 m depth with maximum measured temperatures of 250 °C. While some data are available on diffuse CO2 fluxes, data on CH4 are available only for fumarolic fluids. In the present study we measured CH4 fluxes in the area of Favara Grande characterized by intense diffuse degassing and widespread signs of geothermal activity (fumaroles, steaming grounds and large zones devoid of vegetation). Values range from negative (-43 to 0 mgCH4 m2 day), typical of soils with methanotrophic activity, up to 3500 mgCH4 m2 day in the most thermalized area. The preliminary estimate of the methane release from the area of Favara Grande is about 2.5 t/a. Extrapolation to the whole volcanic/geothermal system of Pantelleria gives about 10 t/a.
    Description: Published
    Description: Davos, Switzerland
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: open
    Keywords: soil gases ; methane output ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 48
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    Miocene–Quaternary structural evolution of the Uyuni–Atacama region, Andes of Chile and Bolivia (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We describe the Miocene–Quaternary geological–structural evolution of the region between the Salar de Uyuni and de Atacama, Andes of Chile and Bolivia. We recognized four main tectonic events based on fold geometry, fault kinematics and stratigraphic data. The oldest event, of Miocene age, is characterized by folding and reverse faulting of the sedimentary successions with an E–W direction of shortening in the northern part of the studied area and a WNW–ESE shortening in the southern part. The following two events, of Pliocene age, are characterized by lower shortening amounts; they occurred first by reverse faulting with a NW–SE-trending greatest principal stress (ó1, computed with striated fault planes) and a vertical least principal stress (ó3), followed by pervasive strike-slip faulting with the same NW–SE-trending ó1 and a horizontal NE–SW ó3. The fourth event, dating to the late Pliocene–Quaternary is characterized by normal faulting: the ó3 still trends NE–SW, whereas the intermediate principal stress ó2 exchanged with ó1. Volcanism accompanied both the contractional, transcurrent and extensional tectonic phases. The Mio–Pliocene compression appears directly linked to a rapid convergence and an apparently important coupling between the continental and oceanic plates. The E–W to WNW–ESE direction of shortening of the Miocene structures and the NW–SE ó1 of the Pliocene structures seem to be more linked to an intra-Andean reorientation of structures following the WNW-directed absolute motion of the South-American Plate. The extensional deformations can be interpreted as related to gravity forces affecting the highest parts of the volcanic belt in a sort of asymmetrical (SW-ward) collapse of the belt.
    Description: Published
    Description: 114-135
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Chile ; Bolivia ; Andes ; Fault ; Fold ; Tectonic phases ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
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  • 49
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    The evolution of a dynamic geological system: the support of a GIS for geochemicd measurements at the fumarole field of Vulcano, Italy (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The island of Vulcano (Aeolian arc, Southern Italy) has displayed several periods of volcanic unrest since the end of the last eruption (1890). We report here results obtained from a long-term survey concerning variations of both the steam output and the exhaling surface area at the sun~mit crater fumarolic field of La Fossa. The field measurements analysed in a Geographiciil Information System (GIS: show a highly dynamic volcanic system in which deep variations in the geochemishy and the temperature of the released fluids were accompanied by fluctuations in the mass output of steam and the topography of the crater field. The use of a GIS facilitated digitized reconstructions of maps of the crater field in addition to analysis (of the steam flux data. The furnarolic field expanded its surface area from 50 m2 in 1983 to more than 2400 m* in 1995, accompanied by an increase in steam output from 152 to about 1400 tonnes per day. The possibility that the observed phenomena are related to volcano-tectonic activity and to magma uprising is taken into consideration.
    Description: Published
    Description: 253-263
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic surveillance ; Steam output ; tectonic lines ; flux ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
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  • 50
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    Geochemical evaluation of observed changes in volcanic activity during the 2007 eruption at Stromboli (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On February 27, 2007 a new eruption started at Stromboli that lasted until April 2 and included a paroxysmal explosion on March 15. Geochemical monitoring carried out over several years revealed some appreciable variations that preceded both the eruption onset and the explosion. The carbon dioxide (CO2) flux from the soil at Pizzo Sopra La Fossa markedly increased a few days before the eruption onset, and continued during lava effusion to reach its maximum value (at 90,000 g m−2 d−1) a few days before the paroxysm. Almost contemporarily, the δ13CCO2 of the SC5 fumarole located in the summit area increased markedly, peaking just before the explosion (δ13CCO2~−1.8‰). Following the paroxysm, helium (He) isotopes measured in the gases dissolved in the basal thermal aquifer sharply increased. Almost contemporarily, the automatic station of CO2 flux recorded an anomalous degassing rate. Also temperatures and the vertical thermal gradient, which had been measured since November 2006 in the soil at Pizzo Sopra La Fossa, showed appreciable variabilities that lasted until the end of the eruption. The geochemical variations indicated the degassing of a new batch of volatile-rich magma that preceded and probably fed the paroxysm. The anomalous 3He/4He ratio suggested that the ascent of a second batch of volatile-rich magma toward the surface was probably responsible of the resumption of the ordinary activity. A comparison with the geochemical variations observed during the 2002–2003 eruption indicated that the 2007 eruption was less energetic.
    Description: Published
    Description: 246-254
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: geochemistry ; eruption ; dissolved gases ; Stromboli ; volcanic activity ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 51
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    Dike propagation in volcanic edifices: Overview and possible developments (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Eruptions are fed by dikes; therefore, better knowledge of dike propagation is necessary to improve our understanding of how magma is transferred and extruded at volcanoes. This study presents an overview of dike patterns and the factors controlling dike propagation within volcanic edifices. Largely based on published data, three main types of dikes (regional, circumferential and radial) are illustrated and discussed. Dike pattern data from 25 volcanic edifices in different settings are compared to derive semi-quantitative relationships between the topography (relief, shape, height, and presence of sector collapses) of the volcano, tectonic setting (presence of a regional stress field), and mean composition (SiO2 content). The overview demonstrates how dike propagation in a volcano is not a random process; rather, it depends from the following factors (listed in order of importance): the presence of relief, the shape of the edifice and regional tectonic control. We find that taller volcanoes develop longer radial dikes, whose (mainly lateral) propagation is independent of the composition of magma or the aspect ratio of the edifice. Future research, starting from these preliminary evaluations, should be devoted to identifying dike propagation paths and likely locations of vent formation at specific volcanoes, to better aid hazards assessment.
    Description: Partly fundedwith DPC-INGVfunds (LAVAProject).
    Description: Published
    Description: 67–77
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: dikes ; volcanoes ; topography ; tectonic setting ; eruptions ; 03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
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  • 52
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    Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamics of the volcano, marking the passage from a period (March 1993–June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveals a southward motion of the upper southern part of the volcano, driven by a NNW–SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
    Description: This work was funded by the Istituto Nazionale di Geofisica e Vulcanologia and by the Dipartimento per la Protezione Civile (Italy).
    Description: Published
    Description: 78–86
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: stress release ; dike ; volcano-tectonics ; flank instability ; Mt. Etna ; instrumental monitoring ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 53
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    Attenuation of body waves in Southeastern Sicily (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The attenuation of P- and S-waves in Southeastern Sicily was estimated by applying two different methods in time and frequency domains. We analyzed waveforms from about 290 local events (0.6 ≤ ML ≤ 4.6) recorded at a three-component digital network. By applying the pulse broadeningmethod to the first P-wave pulse,we found an averageQp value of ca. 140. The application of the frequency decay method provided a Qp value of ca. 120, in the low-frequency band (3–9Hz). Conversely, in the high frequency range (16–27Hz) the average Qp is significantly larger (ca. 640). The frequency decay method was also applied to S-waves spectra. In the low frequency range (2–5Hz) the estimated average Qs is ca. 190. As for Qp, also Qs, in the high frequency range (16–27Hz), is larger (ca. 700). These results evidenced a frequency dependence of both the quality factors Qp and Qs, as commonly observed in tectonically active zones characterized by high degree of heterogeneity
    Description: Published
    Description: 267-279
    Description: JCR Journal
    Description: reserved
    Keywords: attenuation ; body waves ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
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  • 54
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    New geological insights and structural control on fluid circulation in La Fossa cone (Vulcano, Aeolian Islands, Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Electric resistivity tomography (ERT), self-potential (SP), soil CO2 flux, and temperature are used to study the inner structure of La Fossa cone (Vulcano, Aeolian Islands). Nine profiles were performed across the cone with a measurement spacing of 20 m. The crater rims of La Fossa cone are underlined by sharp horizontal resistivity contrasts. SP, CO2 flux, and temperature anomalies underline these boundaries which we interpret as structural limits associated to preferential circulation of fluids. The Pietre Cotte crater and Gran Cratere crater enclose the main hydrothermal system, identified at the centre of the edifice on the base of low electrical resistivity values (b20 Ω m) and strong CO2 degassing, SP, and temperature anomalies. In the periphery, the hydrothermal activity is also visible along structural boundaries such as the Punte Nere, Forgia Vecchia, and Palizzi crater rims and at the base of the cone, on the southern side of the edifice, along a fault attributed to the NW main tectonic trend of the island. Inside the Punte Nere crater, the ERT sections show an electrical resistive body that we interpret as an intrusion or a dome. This magmatic body is reconstructed in 3D using the available ERT profiles. Its shape and position, with respect to the Pietre Cotte crater fault, allows replacing this structure in the chronology of the development of the volcano. It corresponds to a late phase of activity of the Punte Nere edifice. Considering the position of the SP, soil CO2 flux, and temperature maxima and the repartition of conductive zones related to hydrothermal circulation with respect to the main structural features, La Fossa cone could be considered as a relevant example of the strong influence of preexisting structures on hydrothermal fluid circulation at the scale of a volcanic edifice.
    Description: Published
    Description: 231-245
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: partially_open
    Keywords: electrical resistivity ; self-potential ; soil CO2 degassing ; temperature ; fluid circulation ; hydrothermal system ; structural boundary ; Vulcano ; La Fossa cone ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.03. Physical::03.03.02. General circulation ; 04. Solid Earth::04.01. Earth Interior::04.01.01. Composition and state ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 55
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    Seismicity, seismotectonics and crustal velocity structure of the Messina Strait (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Messina Strait is the most important structural element interrupting the southernmost part of the Alpine-Apenninic orogenic belt, known as the Calabro-Peloritan Arc. It is being a narrow fan-shaped basin linking the Ionian Sea to the Tyrrhenian Sea. This region is affected by considerable seismic activity which mirrors the geodynamic processes due to the convergence between the African and the Eurasian plates. In the last four centuries, a significant number of disastrous earthquakes originated along the Arc. Among these, the most noteworthy event occurred on December 28, 1908 (known as the Reggio Calabria-Messina earthquake), in the Messina Strait area and caused a large tsunami and more than 100,000 casualties. In this research we focus on the relationships between the general tectonic setting, which characterize the Messina Strait and adjacent areas, seismicity patterns and the crustal structure. We analyzed a data set consisting of more than 300 events occurring in the years from 1999 to 2007, having a magnitude range from 1.0 to 3.8. This data set was exploited in a local earthquake tomography, by carrying out a simultaneous inversion of both the three-dimensional velocity structure and the distribution of seismic foci. We applied the “tomoADD” algorithm, which uses a combination of absolute and differential arrival times and a concept of self-adapting grid geometry, accounting for ray density encountered across the volume. With this method the accuracy of event locations is improved and velocity structure near the source region is resolved in more detail than standard tomography. Fault plane solutions were obtained for the major and best-recorded earthquakes. The obtained velocity images highlight vertical and lateral heterogeneities that can be associated with structural features striking from NNE-SSW to NE-SW. These results are consistent with important tectonic elements visible at the surface and the pattern delineated by earthquake locations and focal mechanisms.
    Description: Published
    Description: 65-78
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Crustal structure ; Focal mechanism ; Seismicity ; Seismotectonics ; Tomography ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
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  • 56
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    Sweet chestnut (Castanea sativa) leaves as a bio-indicator of volcanic gas, aerosol, and ash deposition onto the flanks of Mt. Etna in 2005-2007 (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Sweet chestnut leaves (Castanea sativa) collected from the flanks of Mt Etna volcano in 2005–2007 were analysed by inductively-coupled plasma mass spectrometry to investigate the spatial and temporal variability of element concentrations. The aim of this work was to determine whether these leaves are a bio-indicator for volcanic gas, aerosol and ash deposition and to gain new insights into the environmental effects of quiescent and eruptive volcanic plumes. Results show a positive correlation between sample variability in the concentration of elements in Castanea sativa and enrichment factors of elements in the plume. The spatial and temporal variability of chalcophilic elements (As, Cd, Cu, Mo, Tl, Zn) is consistent with prevailing winds transporting eruptive plumes to the south-east of the summit, resulting in enhanced plume deposition onto the flanks of the volcano. Similar spatial and temporal variability was found for the halideforming elements (Cs, K, Rb) and intermediate elements (Al, Co, Mn). The spatial variability of chalcophilic, intermediate and halide-forming elements during quiescent periods was diminished (relative to eruptive periods) and could not be explained by plume deposition. In contrast, the concentrations of lithophilic elements (Ba, Ca, Mg, Sr) did not show any clear spatial variability even during eruptive periods. Comparisons between enrichment factors for elements in Castanea sativa and literature values for enrichment factors of the volcanic plume, groundwater and lichen were made. Whilst Castanea sativa offers insights into the spatial and temporal variability of deposition, the species may not be a bio-indicator for plume composition due to biological fractionation.
    Description: Published
    Description: 107-119
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Mt Etna ; vegetation ; Castanea sativa ; bio-indicator ; emission ; dispersion ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 57
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    Reply to comments on “Separation of Qi and Qs from passive data at Mt. Vesuvius: A reappraisal of the seismic attenuation estimates” by Ugalde, A. and Carcolé, E. (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The paper by Del Pezzo et al. (2006), hereafter named DPBZ, deals with the estimate of the seismic attenuation in the high frequency range for the volcanic area of Mt. Vesuvius. In particular DPBZ use a method based on the fit of the observed local earthquake coda envelopes to the radiative transfer classical equation (see Sato and Fehler, 1998 for a wide and exhaustive review on this argument) in terms of the intrinsic attenuation and the scattering attenuation coefficients. Ugalde and Carcolé in their comment (hereafter named UC) discuss two points of DPBZ that we summarize here in their essence: (a) Two approximations of the exact solution of the 3-D radiative transfer model have been calculated, that discussed by Zeng (1991) – hereafter Z91 – expressed by Formula (5) of UC, and that by Paasschens (1997) – hereafter P97 – expressed by Formula (6) of UC. UC show that P97 is more accurate than Z91, which is instead used in DPBZ. (b) DPBZ obtain the separated estimates of intrinsic- and scattering-attenuation coefficients, respectively !i and !s, first stacking the normalized energy envelopes (starting at 2Ts lapse time) and then fitting the experimental data with the normalized (in the same way) theoretical curve. UC disagree with this procedure. Their opinion is that DPBZ should have inverted the single energy envelopes and then have averaged the results obtained. In the following we reply to points (a) and (b) in two separate sections.
    Description: Published
    Description: 195–196
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Seismic scattering ; Elastic attenuation ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 58
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    Radioactivity in waters of Mt. Etna (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Radioactivity in underground waters from Mt. Etna was investigated on the basis of 13 samples. The samples were collected from springs, wells and galleries around the volcano. Water from nine out of thirteen intakes is used for consumption. Activity concentration of uranium isotopes 234,238U, radium isotopes 226,228Ra and radon 222Rn were determined with the use different nuclear spectrometry techniques. The measurements of radium and radon activity concentration were performed with the use of a liquid scintillation counter. The determination of uranium isotopes was carried out with the use of alpha spectrometry. All samples show uranium concentration above Minimum Detectable Activity (MDA), with the highest total uranium (234U þ 238U) activity concentration equal to 130 mBq/l. For radium isotopes, all samples except one showed the activity concentration below MDA. Radon activity concentration was within the range from 1 to 13 Bq/l, hence these waters can be classified as low-radon waters.
    Description: Published
    Description: 384-389
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: Ra-226 ; Ra-228 ; U-238 ; U-234 ; Rn-222 ; Drinking water ; Activity concentration ; Effective dose ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 59
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    Late Matuyama climate forcing on sedimentation at the margin of the southern Alps (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Pleistocene history of climate control on sedimentation in the Southern Alps-Po Plain system, northern Italy, was reconstructed using an integrated magnetostratigraphic, palynological, and petrographical approach on a 47-m-deep core. The core mainly consists of lacustrine sediments pertaining to the Bagaggera sequence, deposited at the foothills of the Southern Alps during the late Matuyama subchron (0.99–0.78 Ma). At that time, climate worsened globally and locally it caused the progradation of an alluvial fan unit onto the nearby Po Plain, triggering lake formation by damming of a tributary valley. These new data are used in conjunction with data from the literature to highlight and track the effects of climate forcing on sedimentation during the late Matuyama subchron in different orographic and geodynamic settings of the Southern Alps-Po Plain system as part of the greater Alpine area. We found that the episodes of alluvial fan and braidplain progradation observed in the southern foreland of the Alps during the late Matuyama global cooling seem broadly synchronous with the deposition of most of the so-called Günz and Älterer Deckenschotter deposits in the northern forelands of the Alps as well as with the first major waxing of the Alpine valley glaciers, possibly around the Marine Isotope Stage 22 (~0.87 Ma).
    Description: In press
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Pleistocene ; magnetostratigraphy ; pollen analysis ; sand petrography ; Alps ; Po Plain ; lacustrine sequence ; alluvial fan ; 02. Cryosphere::02.03. Ice cores::02.03.05. Paleoclimate ; 04. Solid Earth::04.04. Geology::04.04.02. Geochronology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 60
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    Long-term forecast of eruption style and size at Campi Flegrei caldera (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Campi Flegrei caldera is an active and restless volcano in the densely inhabited Neapolitan area of southern Italy. Because of the very high value (lives, properties, infrastructures, etc.) exposed to potential volcanic hazards, it is one of the areas at highest volcanic risk on Earth. In such a situation we have made an attempt to contribute to assessment of its volcanic hazards by providing a quantitative probabilistic longterm forecast of style and size of the next eruption. We have evaluated the most relevant physical parameters of the 22 explosive eruptions of the Campi Flegrei caldera over the past 5 ka. This time span has been taken as the reference period for volcanic hazards assessment on the basis of the volcanic and deformation history of the caldera. The evaluated parameters include dispersal, volume and density of the pyroclastic deposits, volume of erupted magma, total erupted mass, and eruption magnitude. The obtained results permit a size classification of the explosive eruptions, which are grouped into three sizes: small, medium, and large. On the basis of the reconstructed eruption dynamics, we have considered a type event(s) representative of each size class and hypothesized the style of the next event. An effusive eruption will likely generate a dome or very small lava flows, while an explosive event of any size very probably will produce particles fallout and flowage of pyroclastic density currents. Using a Bayesian inference procedure, we have assigned a conditional probability of occurrence to each of the eruption size classes. A small-size explosive eruption is the most likely event with a probability of about 60%; a large-size explosive eruption is the least likely event with a probability of about 4%; a medium-size explosive eruption has a probability of occurrence of about 25%; an effusive eruption has about 11% probability of occurrence.
    Description: Published
    Description: 265–276
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic hazards assessment ; eruption size ; eruption style ; Campi Flegrei caldera ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 61
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    Modelling ground deformation caused by oscillating overpressure in a dyke conduit at Soufrière Hills Volcano, Montserrat (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A dyke conduit has been shown to be a realistic model for the shallow magmatic feeder system for the dome forming eruption at Soufrière Hills Volcano, Montserrat. Here we use a three-dimensional Finite Element model to examine the ground deformation that can be expected due to the pressurization of a dyke conduit. We find that the generated deformation has a bilateral symmetry with nearly no displacement in the direction of dyke strike, and a maximal ground deformation about 1 km away from the vent in the perpendicular direction. Resultant surface deformation is mainly triggered by the upper part of the feeder system, where the dyke opens into a cylindrical conduit. We apply our deformation model to investigate tilt data collected in 1997 in order to infer the orientation of the dyke. We obtain a best-fit for a NNW–SSE trending dyke, which matches observations of the ground displacement field obtained by differential GPS and the alignment of main structural geologic features of southern Montserrat.
    Description: Published
    Description: 87–95
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Soufrière Hills Volcano ; Dyke conduit ; Finite Element Model ; Ground deformation ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 62
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    Remote detection of fumarolic gas chemistry at Vulcano, Italy, using an FT-IR spectral radiometer (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: An infrared absorption spectroscopy remote sensing technique was used to determine the S02/HCl ratio in fumarolic plumes at Vulcano, Italy. The measurements were made from the southern crater rim of Fossa Grande Crater, about 400 m from the fumarolic area in the crater. Infrared absorption spectra of HCl and SO, were observed for four fumaroles a few tens of metres apart using the hot fumarolic surface as an infrared light source. The measured S02/HCl ratios in the FA, F47, FW and lower parti of the F21 fumaroles were 4.5-5.4, 3.5, 9.5-11.2 and 5.8 respectively. The S02/HCl ratio of the FA fumarole was higher than that of the gas collected directly in the fumarolic vent (S02/HCl ratio = 2.9), and was closer to the S~,,,,,,/HCl ratio (= 4.6) of the collected gas. Our results show that the SO,/HCl ratios of two fumaroles only a few tens of metres apart exhibits differences of about twofold. This suggests that this remote monitoring technique is capable of detecting spatial distribution in the S02/HCl ratios of volcanic plumes. Because temporal variations in S/Cl ratios can provide precursory signals for volcanic eruptions [l-31, this remote sensing technique can used efficiently for evaluation of volcanic activity.
    Description: Published
    Description: 219-224
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: open
    Keywords: Gas chemistry ; FTIR ; Volcano ; fumaroles ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 63
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    Sourcing hydrocarbons in CO2-rich in hydrothermal systems (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Methane (CH4) emanating from a continental volcanichydrothermal system in Nisyros, Greece, is processed through the abiogenic reduction of mantle- and marine limestonederived CO2 [1]. Evidence for the occurrence of abiogenic hydrothermal reduction of CO2 is from the chemical and carbon isotopic equilibrium patterns. We have further characterized this abiogenic methane (C1) source for the concentrations of ethane (C2) and propane (C3), as well as for the hydrogen isotopic composition of CH4, H2O, H2 and H2S. C1/C2+ ratios are significantly higher than those typically observed for purely thermogenic sources. Hydrocarbon distribution ratios for other continental-hydrothermal sources rich in CO2 are comparable to those of the Nisyros fumaroles implying that abiogenic methane might be significantly more widespread than previously assumed [2]. Relative concentrations of hydrocarbons in continental-hydrothermal discharges are even indistinguishable from those measured in ultramafic hydrothermal emissions. The fact that redox conditions do not seem to exert any control on the relative concentrations of hydrocarbons in hydrothermal emissions in general, implies that the same two sources account for hydrocarbon production in continental and ultramafic environments. One source generates methane exclusively through the selective abiogenic reduction of CO2 (Sabatierreaction). The other source produces minor amounts of methane, ethane and propane by a random process and represents either the thermal cracking of organic matter or the polymerization starting from methane. Hydrogen isotope partitioning between H2O, H2S, H2 and CH4 in Nisyros fumaroles reveals that isotopic exchange rates are highest for H2O-H2S followed by H2O-H2. In contrast to H2 and H2S, the hydrogen isotopic composition of methane exhibits almost no local variations. This is in agreement with its predominantly abiogenic hydrothermal origin and with the low temperature sensitivity of the hydrogen isotope fractionation factor between water vapor and methane.
    Description: Published
    Description: Davos, Switzerland
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: open
    Keywords: hydrothermal gases ; methane ; ethane ; propane ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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  • 64
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    From mantle to crust: Stretching the Mediterranean (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The origin of forces driving the deformation of the continental crust near subduction zones and especially in backarc regions is debated. Thiswork is based on a compilation of SKS fast splitting directions that give an image of flowlines in themantle around theMediterranean subduction zones and a comparisonwith stretching and shear directions in metamorphic core complexes that show the pattern of deformation at the scale of the middle and lower crusts.We find that : (1) the two sets of directions are parallel in the three main backarc regions, namely the Alboran Sea, the Tyrrhenian Sea and the Aegean Sea showing that the lithosphere deformswith the samedirection of stretching in the crust and themantle, suggesting that (2) crustal deformation ismainly driven frombelowby slab retreat, and (3) the lithospheric fabric is reset within a few millions of years in backarc environments.
    Description: Published
    Description: 198–209
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: subduction ; seismic anisotropy ; backarc extension ; slab retreat ; stretching lineation ; metamorphic core complexes ; Mediterranean ; Aegean ; Tyrrhenian ; Alboran ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 65
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    Pressure dependence of viscosity of rhyolitic melts (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Viscosity of silicate melts is a critical property for understanding volcanic and igneous processes in the Earth. We investigate the pressure effect on the viscosity of rhyolitic melts using two methods: indirect viscosity inference from hydrous species reaction in melts using a piston cylinder at pressures up to 2.8 GPa and direct viscosity measurement by parallel-plate creep viscometer in an internally-heated pressure vessel at pressures up to 0.4 GPa. Comparison of viscosities of a rhyolitic melt with 0.8 wt% water at 0.4 GPa shows that both methods give consistent results. In the indirect method, viscosities of hydrous rhyolitic melts were inferred based on the kinetics of hydrous species reaction in the melt upon cooling (i.e., the equivalence of rheologically defined glass transition temperature and chemically defined apparent equilibrium temperature). The cooling experiments were carried out in a piston-cylinder apparatus using hydrous rhyolitic samples with 0.8–4 wt% water. Cooling rates of the kinetic experiments varied from 0.1 K/s to 100 K/s; hence the range of viscosity inferred from this method covers 3 orders of magnitude. The data from this method show that viscosity increases with increasing pressure from 1 GPa to 3 GPa for hydrous rhyolitic melts with water content 0.8 wt% in the high viscosity range. We also measured viscosity of rhyolitic melt with 0.13 wt% water using the parallel-plate viscometer at pressures 0.2 and 0.4 GPa in an internally-heated pressure vessel. The data show that viscosity of rhyolitic melt with 0.13 wt% water decreases with increasing pressure. Combining our new data with literature data, we develop a viscosity model of rhyolitic melts as a function of temperature, pressure and water content.
    Description: NSF Grants EAR-0537598 and EAR-0711050
    Description: Published
    Description: 3680-3693
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: viscosity ; rhyolite ; water species ; pressure ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 66
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    Filling the North European Early/Middle Eocene (Ypresian/Lutetian) boundary gap: Insights from the Pyrenean continental to deep-marine record (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Early/Middle Eocene (Ypresian/Lutetian) transition is represented by a hiatus in many North European sections, including those in which the classic stratotypes were originally defined. However, the Global Stratotype Section and Point of the Lutetian Stage, which is still pending definition, should be placed at a globally correlatable event included within that unrepresented interval. The Pyrenean Eocene outcrops display sedimentary successions that offer the rare opportunity to analyse the Ypresian/Lutetian boundary interval in almost continuous sections and in very different settings. Seven reference stratigraphic sections were selected on the basis of their quality and correlated by means of biomagnetostratigraphic data. This correlation framework casts light on the sequence of chronostratigraphic events that characterize the Ypresian/Lutetian boundary interval, which may prove useful in defining the main correlation criterion of the base of the Lutetian. All of the Pyrenean sections show a similar sedimentary evolution, despite being up to 350 km apart from each other, containing deposits of different origins (intrabasinal carbonate sediments, siliciclastic sediments sourced from the Iberian plate, and terrigenous sediments sourced from the uplifting Pyrenees) and despite having been accumulated in different sedimentary environments (from continental to deep marine) and in different geodynamic settings (piggy-back basin, foreland basin and cratonic margin). This common evolution can be readily interpreted in terms of a sea-level driven depositional sequence whose lowstand and transgressive systems tracts are included within the Ypresian/Lutetian boundary interval. The Pyrenean Ypresian/Lutetian depositional sequence can reasonably be correlated with depositional sequences from classic North European areas, shedding light on the palaeoenvironmental history which in those areas has not been recorded. Furthermore, these depositional sequences may possibly correlate with others from the Antarctic Ocean and from New Jersey, as well as with oceanic temperature variations, suggesting that they might be the result of climatically-driven glacioeustatic sea-level changes. Should this hypothesis prove correct, it would confirm previous suggestions that the onset of Antarctic glaciations needs to be backshifted to the late Ypresian at least.
    Description: Published
    Description: 313-332
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Eocene ; Lutetian ; Chronostratigraphy ; Sequence stratigraphy ; Climate ; Pyrenees ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 67
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    Nitrogen Isotopes in Volcanic Fluids of Different Geodynamic Settings (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Nitrogen isotopes , N2/36Ar and 3He/4He were measured in volcanic fluids within different geodynamic settings. Subduction zones are represented by Aeolian archipelago, Mexican volcanic belt and Hellenic arc, spreading zones – by Socorro island in Mexico and Iceland and hot spots by Iceland and Islands of Cabo Verde. The δ15N values, corrected for air contamination of volcanic fluids, discharged from Vulcano Island (Italy), highlighted the presence of heavy nitrogen (around +4.3 ±0.5‰). Similar 15N values (around +5‰), have been measured for the fluids collected in the Jalisco Block, that is a geologically and tectonically complex forearc zone of the northwestern Mexico [1]. Positive values (15N around +3‰) have been also measured in the volcanic fluids discharged from Nysiros island located in the Ellenic Arc characterized by subduction processes. All uncorrected data for the Socorro island are in the range of -1 to -2‰. The results of raw nitrogen isotope data of Iceland samples reveal more negative isotope composition (about -4.4‰). On the basis of the non-atmospheric N2 fraction (around 50%) the corrected data of 15N for Iceland are around -16‰, very close to the values proposed by [2]. In a volcanic gas sample from Fogo volcano (Cabo Verde islands) we found a very negative value: -9.9‰ and -15‰ for raw and corrected values, respectively.
    Description: Geochimica et Cosmochimica Acta
    Description: Published
    Description: Davos, Switzerland
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: open
    Keywords: Nitrogen Isotopes ; Helium Isotopes ; Volcanic fluids ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 68
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    Hydrothermal methane fluxes from the soil at Pantelleria island (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Chemical and isotopic analyses of the main gas manifestations of the island of Pantelleria (Italy) were used to gain insight on the origin of the released methane. Results indicate that the most probable origin is through abiogenic reactions within the hydrothermal system. Methane and CO2 flux measurements from the soils were made with the accumulation chamber method in an area of about 0.015 km2 within the main fumarolic area of the island (Favara Grande). The 23 measurements range from –34 to 3550 mg m-2 d-1 for CH4 and from 0.6 to 379 g m-2 d-1 for CO2. The relationships between CH4 and CO2 fluxes and the CH4/CO2 ratios in the gases collected between 25 and 100 cm depth provide evidence for methanotrophic processes within the soils. Methane output for the surveyed area was calculated in 2.5 t a-1 and extrapolated to about 5-10 t a-1 for the entire volcanic/hydrothermal system of the island. Previous higher estimates of the CH4 output at Pantelleria (Etiope et al., 2007 - J. Volcanol. Geotherm. Res., 165, 76 – 86) were based on soil CO2 output and CH4/CO2 ratios in fumarolic gases; the present work provides the first direct CH4 flux data and it suggests that methanotrophic activity in the soil could be substantial in reducing the CH4 emission to the atmosphere.
    Description: Published
    Description: 147-157
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: hydrothermal systems ; gas geochemistry ; isotope composition ; methane output ; methanotrophic consumption ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 69
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    Volcanic signature of volatile trace elements on atmospheric deposition at Mt. Etna, Italy (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Volcanic volatiles and aerosol emitted into the atmosphere ultimately fall on the Earth’s surface as wet or dry deposition, and they can influence the environment and the ecosystems at local and regional scales. Therefore, atmospheric deposition plays a key-role in the geochemical cycles, redistributing volcanogenic elements to the ground. For this reason, estimating the volcanogenic trace element fluxes from the atmosphere to the surface is necessary for a better knowledge of the environmental impact of the volcanic emissions. Nevertheless, from a literature review, we have recognized the scarcity of investigation on trace element deposition in the surroundings of active volcanoes. Here, we present a chemical characterization of bulk deposition around Mt. Etna, Italy, including both major and many trace elements. Bulk depositions were collected approximately fortnightly, from April 2006 to December 2007, using a network of five rain gauges, located at various altitudes on the upper flanks around the summit craters of the volcano. For most elements highest concentrations have been found close to the emission vent, confirming the prevailing volcanic contribution to rainwater composition close to the summit craters. Comparison with contemporaneously collected plume emissions shows that deposition processes produce no evident element-to-element fractionation. By contrast, comparison with whole rock composition indicates a contrasting behaviour between volatile elements, which are highly-enriched in rainwater, and refractory elements, which have low rainwater/whole rock concentration ratios. Chemical concentrations in bulk deposition were used to estimate the deposition rates of a large suite of elements. Deposition rates for volatile trace elements like Se, As, and Cd range from 1.7, 1.2 and 0.9 µg m-2 day-1 nearby to the summit vents, to 0.5, 0.3, and 0.1 µg m-2 day-1 at the local background site on the upwind western sector.
    Description: Published
    Description: Davos, Switzerland
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: open
    Keywords: trace metals ; atmospheric deposition ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.08. Risk::05.08.01. Environmental risk
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  • 70
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    Volcanic unrest of the Colli Albani (central Italy) detected by GPS monitoring test (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Colli Albani volcanic complex, located in central Italy about 15km SE of Rome, has been dominated by periodic eruptive histories started about 561 ka and ending with the most recent and voluminous activity of the Albano maar (〈70 ka) phase. Earthquakes of moderate intensity, gas emissions and significant ground deformations are the recent evidences of a residual activity. We decided to start a monitoring test by installing as first step three GPS permanent stations on the volcanic structure, in sites easily accessible. The analysis of about 2 years of GPS observations has evidenced a peculiar velocity pattern of the Colli Albani stations with respect to those located nearby, but outside the volcano edifice. With respect to Eurasia, the horizontal velocities are NE directed with magnitudes of 2.2±1.4mm/year (RDPI), 3.0±0.8mm/year (RMPO) and 3.3±1.2mm/year (NEMI). The uplift rates are determined with minor accuracy and range from 3.3 and 6.0mm/year. We used a non-linear inversion algorithm to determine the best-fit parameters for a Mogi spherical source based on the Levenberg–Marquardt least squares approach. The best-fit is obtained with a source at 4.6km depth beneath thewestern flank of the volcano and a volume variation of 3.6×10−4 km3/year. This result is in agreement with the volume rate retrieved by PS-InSAR technique and rather different from the rate inferred from leveling surveys. Consequently, non-linear trends of the hydrothermal system charge cannot be excluded apriori and the continuous GPS monitoring should be considered a priority in assessing the hazard of the Colli Albani.
    Description: This work has been partially supported by the Dept. of Civil Protection, Project DPC115 V3 Colli Albani.
    Description: Published
    Description: 79-87
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Colli Albani ; GPS ; Volcano monitoring ; Mogi source ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 71
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    Inferences on active faults at the Southern Alps–Liguria basin junction from accurate analysis of low energy seismicity (2009)
    Elsevier
    Details
    Publication Date: 2017-04-03
    Description: Seismotectonic studies concern themselves with understanding the distribution of earthquakes in space, time, size and style. Therefore, the better these parameters are known, the most correct the association of any seismic event with the faulting structure that caused it will result. The use of accurate location methods is especially required when dealing with very complex areas, where several faulting systems or relatively small seismogenic structures exist. In fact, even though routinely determined epicentres are capable of revealing the rough picture of the seismicity, they are not suitable for studies of the fine structure of the causative fault, as their location uncertainties are often larger than the source dimension itself. In this work the probabilistic approach of the “Non Linear Localization” has been used to compute precise locations for earthquakes occurred in the last twenty years nearby the Saorge–Taggia line, a complex fault system situated in Western Liguria, close to the border between Italy and France. Together with the Breil– Sospel–Monaco and the Peille–Laghet faults, this line is responsible for the seismic activity of the area. The seismotectonic study is completed through a local tomographic study and the analysis of the focal mechanisms computed for an enlarged area. The results show that the seismicity associated with this fault system is confined within the first 10 km depth. Many clusters of seismic events are identified along the Saorge–Taggia line. The existence of a not previously mapped branch perpendicular to the Saorge–Taggia line is also recognized. Although its position may suggest it to be the continuation of the Breil–Sospel–Monaco fault system towards NE, our finding would rather suggest no association with the fault. The overall results confirm the complexity of the area; in particular the hypothesis that the Saorge–Taggia system may represent the eastward limit of a subalpine crustal block comprised within the Nice Arc, the named fault and a thrust front which is supposed to be located 20 km offshore find a confirm in the shallow depth of the seismic events. In addition we propose that the western limit of the block, located along the Nice arc, could be instead shifted where the Peille–Laghet fault lays.
    Description: Published
    Description: 470-479
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: High precision locations ; Focal mechanisms ; Fault geometry ; Western Liguria ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 72
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    Converted phases analysis of the Campi Flegrei caldera using active seismic data (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We applied a type of depth migration for converted seismic phases to active and passive seismic data sets from the Campi Flegrei volcanic region in southern Italy. The migration method is based on the diffraction summation migration technique. Travel times to grid points in a volume were calculated in smooth P and S-velocity models and trace energy near the calculated converted phase time was stacked over multiple sources at one receiver. Weighting factors based on Snell's Law at an arbitrarily oriented local interface were applied to better focus trace energy. PP reflection images from the active data set provide increased detail to images of the caldera rim from other studies. The migrated images also show features near 2–3 km in depth beneath Pozzuoli City, which may be associated with an over-pressured gas volume, as suggested by other geophysical investigations. Possible deeper features near 4 km depth may be related to the presence of the carbonate basement or may image a previously undetected feature, such as a small body of strongly thermometamorphosed volcanic rock. The current passive earthquake data set from the 1984 ground uplift episode was not well suited to the converted phases analysis due to narrow P–S windows and high noise levels in the traces. However, two stations provide confirmation and extension of imaged features in the active data.
    Description: Published
    Description: 243-256
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: converted phases ; migration ; seismic imaging ; Caampi Flegrei ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 73
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    Modeling unusual eruptive behavior of Mt. Etna, Italy, by means of event bush (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: One of the best-studied volcanoes of the world, Mt. previous termEtnanext term in Sicily, repeatedly exhibits eruptive scenarios that depart from the behavior commonly considered typical for this volcano. Episodes of intense explosive activity, pyroclastic flows, dome growth and cone collapse pose a variety of previously underestimated threats to human lives in the summit area of the volcano. However, retrospective analysis of these events shows that they were likely caused by the same very sets of premises and starting conditions as “normal” eruptions, yet combined in an unexpected, probably unique, way. To cope with such unexpected consequences, we involve an approach of artificial intelligence developed specially for needs of the geosciences, the event bush. Scenarios inferred from the event bush fit the observed ones and allow to foresee other low-probability events that may occur at the volcano. Application of the event bush provides a more impartial vision of volcanic phenomena and may serve as an intermediary between expert knowledge and numerical assessment, e.g., by means of Bayesian Belief Networks.
    Description: Published
    Description: 157-171
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; Event bush method ; artificial intelligence ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 74
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    Three-years of SO2 flux measurements of Mt. Etna using an automated UV scanner array: Comparison with conventional traverses and uncertainties in flux retrieval (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Routine measurements of SO2 flux using the traverse method on Mt. Etna (Italy) were augmented in late 2004 when an array of automatic scanning ultraviolet spectrometers was installed. Each instrument allows one SO2 scan to be recorded every ~6 min. Here we report the methods that we developed to automatically and robustly transform SO2 profiles into SO2 flux data. Radian geometry and Fast Fourier Transform algorithm were used for reducing plume cross-sections and for discriminating between volcanic plumes from those produced by water vapour clouds. Uncertainty in flux measurements depends on the accuracy of plume height estimation, on assumptions concerning plume-geometry, and on the quality of the retrieved SO2 amounts. We compare 3 years of flux measurements made using both the automated network and “conventional” traverse methods beneath the plume.We found a good agreement between the datasets, both in terms of magnitude and in temporal variations. These results validate the Etna SO2 flux monitoring system. Emission rates are available to the 24-hour manned operations room via intranet, providing real-time information on degassing rates and plume location.
    Description: (1)Sviluppo di sistemi di monitoraggio Dipartimento di Protezione Civile della Regione Sicilia, (2)INGV (Istituto Nazionale di Geofisica e Vulcanologia, sezione di Catania — Italy), (3)NOVAC (Network for Observation of Volcanic and Atmospheric Change)EU-funded Sixth Framework Programme project 18354. ()4 UK NERC National Centre for Earth Observation via the “Dynamic Earth and geo-hazards”.
    Description: Published
    Description: 76-83
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: sulphur dioxide, scanning spectrometer, car-based traverse, DOAS, Mt. Etna, volcano surveillance ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 75
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    Novel retirval of volcanic SO2 abundance form ultraviolet spectra (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The recent development of fixed networks of scanning ultraviolet spectrometers for automatic determination of volcanic SO2 fluxes has created tremendous opportunities for monitoring volcanoes but has brought new challenges in processing (and interpreting) the copious data flow they produce. A particular difficulty in standard implantation of differential optical absorption (DOAS) methods is the requirement for a clear-sky (plume-free) background spectrum. Our experience after four years of measurements with two UV scanner networks on Etna and Stromboli shows that wide plumes are frequently observed, precluding simple selection of clear-sky spectra. We have therefore developed a retrieval approach based on simulation of the background spectrum. We describe the method here and tune it empirically by collecting clear, zenith sky spectra using calibration cells containing known amounts of SO2. We then test the performance of this optimised retrieval using clear-sky spectra collected with the same calibration cells but for variable scan angles, time of day, and season (through the course of 1 year), finding acceptable results (~12% error) for SO2 column amounts. We further illustrate the analytical approach using spectra recorded at Mt. Etna during its July 2006 eruption. We demonstrate the reliability of the method for tracking volcano dynamics on different time scales, and suggest it is widely suited to automated SO2-plume monitoring
    Description: (1)FIRB-MIUR “Simulazione dei flussi lavici con gli automi cellulari” N. RBAU01RMZ4_002 and “Sviluppo di sistemi di monitoraggio' Dipartimento di Protezione Civile della Regione Sicilia, INGV(Istituto Nazionale di Geofisica e Vulcanologia, sezione di Catania – Italy). (2) EU-funded Sixth Framework Programme project 18354 “NOVAC” (Network forObservation of Volcanic and Atmospheric Change). (3) Leverhulme Trust fellowship
    Description: Published
    Description: 141-153
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcanic Gas Monitoring, Scanning spectrometer network, DOAS, Ultraviolet Spectroscopy, Mt. Etna ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 76
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    Geochemical and B–Sr–Nd isotopic evidence for mingling and mixing processes in the magmatic system that fed the Astroni volcano (4.1–3.8 ka) within the Campi Flegrei caldera (southern Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Astroni volcano was built through seven eruptions that generated pyroclastic deposits and lava domes within the Campi Flegrei caldera (southern Italy) 4.1–3.8 ka BP. Whole-rock geochemical and B–Sr–Nd isotopic investigations were carried out on representative samples of all seven eruptions. The products vary from tephriphonolites to phonolites, and from latites to trachytes. They show textural, mineralogical and isotopic evidence of disequilibrium, including distinct clinopyroxene populations, rounded and/or resorbed plagioclase and alkali-feldspar, and reverse-zoned phenocrysts of all these mineral phases. The Sr, Nd and B isotopic composition of whole rocks is variable and correlated with the degree of chemical evolution, suggesting open-system processes in addition to fractional crystallisation. Moreover, significant Sr-isotopic disequilibrium between the phenocrysts and glass has been documented for one sample. The chemostratigraphy of the products indicates that Astroni eruptions 1 through 5 were fed by magmas of trachytic to phonolitic composition that were less enriched in radiogenic Sr and 11B up-section. This variability has been interpreted as the result of mingling between at least two distinct magmatic endmembers, one more evolved and the other less evolved. Another heterogeneous batch of magma, resulting from almost complete mixing between the same two end-members, was drained during eruptions 6 and 7. The more evolved end-member, characterised by 87Sr/86Sr≥0.7075, 143Nd/144Nd≤0.51247 and δ11B≥−8‰, was very similar to the magma that fed the final phases of the Agnano–Monte Spina eruption, which occurred a few centuries earlier in the Astroni vent area. The less evolved end-member had 87Sr/ 86Sr≤0.70726, 143Nd/144Nd≥0.51251 and δ11B≤10‰, and was likely derived by fractional crystallisation of a mantle-derived magma. An abrupt decrease in both the Sr isotope ratio and the Th content, detected at the transition between Unit 4 and 5, suggests that another magma with a 87Sr/86Sr ratio intermediate between those of the two identified end-members may have been involved in Astroni activity. The more evolved endmember is interpreted as a residue of the Agnano–Monte Spina eruption that was invaded by either the intermediate or the less evolved magmatic end-member, promoting mingling and triggering Astroni activity. This study of Astroni provides insights for both short- and long-term volcanic hazard assessment, as the Astroni volcano is the best example of a very close sequence of eruptions from the same vent area in the Campi Flegrei caldera.
    Description: Published
    Description: 135–151
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Campi Flegrei caldera ; B–Sr–Nd isotope geochemistry ; Magma mingling/mixing ; Chemostratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 77
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    Effect of different seawater Mg2 + concentrations on calcification in two benthic foraminifers (2014)
    Elsevier
    In:  EPIC3Marine Micropaleontology, Elsevier, 113, pp. 56-64, ISSN: 0377-8398
    Details
    Publication Date: 2019-08-19
    Description: Magnesium, incorporated in foraminiferal calcite (Mg/CaCC), is used intensively to reconstruct past seawater temperatures but, in addition to temperature, the Mg/CaCC of foraminiferal tests also depends on the ratio of Mg and Ca in seawater (Mg/CaSW). The physiological mechanisms responsible for these proxy relationships are still unknown. This culture study investigates the impact of different seawater [Mg2 +] on calcification in two benthic foraminiferal species precipitating contrasting Mg/CaCC: Ammonia aomoriensis, producing low-Mg calcite and Amphistegina lessonii, producing intermediate-Mg calcite. Foraminiferal growth and test thickness were determined and, Mg/Ca was analyzed using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). Results show that at present-day seawater Mg/CaSW of ~ 5, both species have highest growth rates, reflecting their adaptation to modern seawater element concentrations. Test thickness is not significantly affected by different Mg/CaSW. The relationship between Mg/CaSW and Mg/CaCC shows a distinct positive y-axis intercept, possibly reflecting at least two processes involved in foraminiferal biomineralization. The associated Mg partition (DMg) changes non-linearly with increasing Mg/CaSW, hence suggesting that the DMg is best described by an exponential function approaching an asymptote.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
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  • 78
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    Modeling organic iron-binding ligands in a three-dimensional biogeochemical ocean model (2014)
    Elsevier
    In:  EPIC3Marine Chemistry, Elsevier, ISSN: 0304-4203
    Details
    Publication Date: 2015-01-05
    Description: Most dissolved iron in the ocean is bound to organic molecules with strong conditional stability constants, known as ligands that are found at concentrations ranging from 0.2 to more than 10 nmol L− 1. In this work we report the first mechanistic description of ligand dynamics in two three-dimensional models of ocean biogeochemistry and circulation. The model for ligands is based on the concept that ligands are produced both from organic matter remineralization and phytoplankton processes, and that they are lost through bacterial and photochemical degradation, as well as aggregation and to some extent in the process of phytoplankton uptake of ligand-bound iron. A comparison with a compilation of in-situ measurements shows that the model is able to reproduce some large-scale features of the observations, such as a decrease in ligand concentrations along the conveyor belt circulation in the deep ocean, lower surface and subsurface values in the Southern Ocean, or higher values in the mesopelagic than in the abyssal ocean. Modeling ligands prognostically (as opposed to assuming a uniform ligand concentration) leads to a more nutrient-like profile of iron that is more in accordance with data. It however, also leads to higher surface concentrations of dissolved iron and negative excess ligand L⁎ in some ocean regions. This is probably an indication that with more realistic and higher ligand concentrations near the surface, as opposed to the traditionally chosen low uniform concentration, iron modelers will have to re-evaluate their assumption of low scavenging rates for iron. Given their sensitivity to environmental conditions, spatio-temporal variations in ligand concentrations have the potential to impact primary production via changes in iron limitation.
    Repository Name: EPIC Alfred Wegener Institut
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  • 79
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    Evaluation of long chain 1,14-alkyl diols in marine sediments as indicators for upwelling and temperature (2014)
    Elsevier
    In:  EPIC3Organic Geochemistry, Elsevier, 76, pp. 39-47, ISSN: 0146-6380
    Details
    Publication Date: 2015-01-13
    Description: Long chain alkyl diols form a group of lipids occurring widely in marine environments. Recent studies have suggested several palaeoclimatological applications for proxies based on their distributions, but have also revealed uncertainty about their applicability. Here we evaluate the use of long chain 1,14-alkyl diol indices for reconstruction of temperature and upwelling conditions by comparing index values, obtained from a comprehensive set of marine surface sediments, with environmental factors such as sea surface temperature (SST), salinity and nutrient concentration. Previous studies of cultures indicated a strong effect of temperature on the degree of saturation and the chain length distribution of long chain 1,14-alkyl diols in Proboscia spp., quantified as the diol saturation index (DSI) and diol chain length index (DCI), respectively. However, values of these indices for surface sediments showed no relationship with annual mean SST of the overlying water. It remains unknown as to what determines the DSI, although our data suggest that it may be affected by diagenesis, while the relationship between temperature and DCI may be different for different Proboscia species. In addition, contributions from algae other than Proboscia diatoms may affect both indices, although our data provide no direct evidence for additional long chain 1,14-alkyl diol sources. Two other indices using the abundance of 1,14-diols vs. 1,13-diols and C30 1,15- diols have been applied previously as indicators for upwelling intensity at different locations. The geographical distribution of their values supports the use of 1,14 diols vs. 1,13 diols [C28 + C30 1,14-diols]/[(C28 + C30 1,13-diols) + (C28 + C30 1,14-diols)] as a general indicator for high nutrient or upwelling conditions.
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  • 80
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    Cenozoic Arctic Ocean Climate History: Some highlights from the IODP Arctic Coring Expedition (ACEX) (2014)
    Elsevier
    In:  EPIC3Developments in Marine Geology, Elsevier, 7, pp. 259-293, ISSN: ISBN: 978-0-444-62617-2
    Details
    Publication Date: 2015-04-23
    Repository Name: EPIC Alfred Wegener Institut
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  • 81
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    Generation of unusual branched long chain alkanes from hydrous pyrolysis of anammox bacterial biomass (2014)
    Elsevier
    In:  EPIC3Organic Geochemistry, Elsevier, 76, pp. 136-145
    Details
    Publication Date: 2015-03-08
    Repository Name: EPIC Alfred Wegener Institut
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  • 82
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    Temperature trends during the Present and Last Interglacial periods – a multi-model-data comparison (2014)
    Elsevier
    In:  EPIC3Quaternary Science Reviews, Elsevier, 99, pp. 224-243, ISSN: 0277-3791
    Details
    Publication Date: 2015-12-14
    Description: Though primarily driven by insolation changes associated with well-known variations in Earth's astronomical parameters, the response of the climate system during interglacials includes a diversity of feedbacks involving the atmosphere, ocean, sea ice, vegetation and land ice. A thorough multi-model-data comparison is essential to assess the ability of climate models to resolve interglacial temperature trends and to help in understanding the recorded climatic signal and the underlying climate dynamics. We present the first multi-model-data comparison of transient millennial-scale temperature changes through two intervals of the Present Interglacial (PIG; 8–1.2 ka) and the Last Interglacial (LIG; 123–116.2 ka) periods. We include temperature trends simulated by 9 different climate models, alkenone-based temperature reconstructions from 117 globally distributed locations (about 45% of them within the LIG) and 12 ice-core-based temperature trends from Greenland and Antarctica (50% of them within the LIG). The definitions of these specific interglacial intervals enable a consistent inter-comparison of the two intervals because both are characterised by minor changes in atmospheric greenhouse gas concentrations and more importantly by insolation trends that show clear similarities. Our analysis shows that in general the reconstructed PIG and LIG Northern Hemisphere mid-to-high latitude cooling compares well with multi-model, mean-temperature trends for the warmest months and that these cooling trends reflect a linear response to the warmest-month insolation decrease over the interglacial intervals. The most notable exception is the strong LIG cooling trend reconstructed from Greenland ice cores that is not simulated by any of the models. A striking model-data mismatch is found for both the PIG and the LIG over large parts of the mid-to-high latitudes of the Southern Hemisphere where the data depicts negative temperature trends that are not in agreement with near zero trends in the simulations. In this area, the positive local summer insolation trend is counteracted in climate models by an enhancement of the Southern Ocean summer sea-ice cover and/or an increase in Southern Ocean upwelling. If the general picture emerging from reconstructions is realistic, then the model-data mismatch in mid and high Southern Hemisphere latitudes implies that none of the models is able to resolve the correct balance of these feedbacks, or, alternatively, that interglacial Southern Hemisphere temperature trends are driven by mechanisms which are not included in the transient simulations, such as changes in the Antarctic ice sheet or meltwater-induced changes in the overturning circulation.
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  • 83
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    New aeromagnetic view of the geological fabric of southern Dronning Maud Land and Coats Land, East Antarctica (2014)
    Elsevier
    In:  EPIC3Gondwana Research, Elsevier, 25(1), pp. 358-367, ISSN: 1342-937X
    Details
    Publication Date: 2017-10-17
    Description: The ice shield of Antarctica, which measures several kilometers in thickness, presents a challenge when attempting to unravel the subglacial geology. Here, we report about systematic airborne magnetic surveys conducted over the last decade, which investigated a significant part of Dronning Maud Land (DML), imaging for the first time the crustal architecture of the interior of this sector of East Antarctica. High-resolution data reveal parallel, elongated magnetic anomalies in southeastern DML. These NW–SE trending anomalies can be traced farther east into sparser Russian magnetic data sets. Several high amplitude magnetic anomalies with values above 400 nT have been observed in southwesternDML and Coats Land. They differ clearly inwavelength and amplitudes fromthe magnetic pattern found in the east and do not show any evidence of a Pan-African orogenic belt or suture zone connecting the Shackleton Range with easternDML, as hypothesized in several studies. This leads to the assumption of the existence of a hitherto unrecognized large tectonic province in southeastern DML.Whereas an over 100 km long magnetic lineament in the interior of the DronningMaud Landmay reflect a major shear zone akin to the Pan-African age Heimefrontfjella shear zone. Both findings bring new evidences to the still open question about the amalgation of East and West Gondwana. In addition, the magnetic data allow mapping the eastern extent of the presumable cratonic province of Coats Land, a region considered as a key piercing point for reconstructions of Rodinia. Furthermore, the Beattie Magnetic Anomaly in southern Africa is assumed to continue into East Antarctica. Two magnetic highs in western DML are identified as possible eastward continuation of this prominent anomaly.
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  • 84
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    Reconstruction of changes in the Weddell Sea sector of the Antarctic Ice Sheet since the Last Glacial Maximum (2014)
    Elsevier
    In:  EPIC3Quaternary Science Reviews, Elsevier, 100, pp. 111- 136, ISSN: 0277-3791
    Details
    Publication Date: 2018-08-10
    Description: Abstract The Weddell Sea sector is one of the main formation sites for Antarctic Bottom Water and an outlet for about one fifth of Antarctica's continental ice volume. Over the last few decades, studies on glacial–geological records in this sector have provided conflicting reconstructions of changes in ice-sheet extent and ice-sheet thickness since the Last Glacial Maximum (LGM at ca 23–19 calibrated kiloyears before present, cal ka BP). Terrestrial geomorphological records and exposure ages obtained from rocks in the hinterland of the Weddell Sea, ice-sheet thickness constraints from ice cores and some radiocarbon dates on offshore sediments were interpreted to indicate no significant ice thickening and locally restricted grounding-line advance at the LGM. Other marine geological and geophysical studies concluded that subglacial bedforms mapped on the Weddell Sea continental shelf, subglacial deposits and sediments over-compacted by overriding ice recovered in cores, and the few available radiocarbon ages from marine sediments are consistent with major ice-sheet advance at the LGM. Reflecting the geological interpretations, different ice-sheet models have reconstructed conflicting {LGM} ice-sheet configurations for the Weddell Sea sector. Consequently, the estimated contributions of ice-sheet build-up in the Weddell Sea sector to the {LGM} sea-level low-stand of ~130 m vary considerably. In this paper, we summarise and review the geological records of past ice-sheet margins and past ice-sheet elevations in the Weddell Sea sector. We compile marine and terrestrial chronological data constraining former ice-sheet size, thereby highlighting different levels of certainty, and present two alternative scenarios of the {LGM} ice-sheet configuration, including time-slice reconstructions for post-LGM grounding-line retreat. Moreover, we discuss consistencies and possible reasons for inconsistencies between the various reconstructions and propose objectives for future research. The aim of our study is to provide two alternative interpretations of glacial–geological datasets on Antarctic Ice-Sheet History for the Weddell Sea sector, which can be utilised to test and improve numerical ice-sheet models.
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  • 85
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    Neoglacial change in deep water exchange and increase of sea-ice transport through eastern Fram Strait: evidence from radiogenic isotopes (2014)
    Elsevier
    In:  EPIC3Quaternary Science Reviews, Elsevier, 92, pp. 190-207, ISSN: 0277-3791
    Details
    Publication Date: 2014-06-02
    Description: Sediment core MSM5/5-712 from the West Spitsbergen continental margin has been investigated at high resolution for its seawater-derived neodymium (Nd) and lead (Pb) isotope compositions stored in ferromanganese oxyhydroxide coatings of the sediment particles to reconstruct Holocene changes in the sources and mixing of bottom waters passing the site. The radiogenic isotope data are used in combination with a multitude of proxy indicators for the climatic and oceanographic development of the eastern Fram Strait during the past 8500 years. To calibrate the downcore data, seawater and core top samples from the area were analysed for their radiogenic isotope compositions. Core top leachates reveal relatively high (more radiogenic) Nd isotope compositions between εNd −9.7 and −9.1, which are higher than present-day seawater εNd in eastern Fram Strait (−12.6 to −10.5) and indicate that the seawater values have only been established very recently. The core top data agree well with the downcore signatures within the uppermost 40 cm of the sediment core (εNd −9.1 to −8.8) indicating a reduced inflow of waters from the Nordic Seas, concurrent with cool conditions and a south-eastward shift of the marginal ice zone after ca 2.8 cal ka BP (Late Holocene). High sea-ice abundances in eastern Fram Strait are coeval with the well-known Neoglacial trend in the northern North Atlantic region. In contrast, warmer conditions of the late Early to Mid-Holocene were accompanied by lower (less radiogenic) εNd signatures of the bottom waters indicating an increased admixture from the Nordic Seas (−10.6 to −10.1). A shift to significantly more radiogenic εNd signatures of the detrital material also occurred at 3 cal ka BP and was accompanied by a marked increase in supply of fine-grained ice-rafted material (IRF) from the Arctic Ocean to the core site. The most likely source areas for this radiogenic material are the shallow Arctic shelves, in particular the Kara Sea shelf. The evolution of the Pb isotope compositions of past seawater was dominated by local signatures characterized by high 208, 207, 206Pb/204Pb values during the warm Early and Mid-Holocene periods related to enhanced chemical weathering on Svalbard and high glacial and riverine input derived from young granitic (more radiogenic) material to the West Spitsbergen margin. At 3 cal ka BP both detrital and seawater Pb isotope data changed towards more Kara Sea-like signatures.
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  • 86
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    A multibiomarker approach to the assessment of pollution impacts in two Baltic Sea coastal areas in Sweden using caged mussels (Mytilus trossulus) (2014)
    Elsevier
    In:  EPIC3Science of The Total Environment, Elsevier, 473-47, pp. 398-409, ISSN: 0048-9697
    Details
    Publication Date: 2019-07-17
    Description: Blue mussels (Mytilus trossulus) were transplanted in cages for three months in two Swedish coastal areas in the Bothnian Sea (northern Baltic Sea) to investigate the interactions between analysed environmental chemicals and biological responses. A wide array of biological parameters (biomarkers) including antioxidant and biotransformation activity, geno-, cyto- and neurotoxic effects, phagocytosis, bioenergetic status and heart rate were measured to detect the possible effects of contaminants. Integrated Biomarker Response index and Principal Component Analysis performed on the individual biological response data were able to discriminate between the two study areas as well as the contaminated sites from their respective local reference sites. The two contaminated sites outside the cities of Sundsvall (station S1) and Gävle (station G1) were characterised by different biomarker response patterns. Mussels at station S1 showed a low condition index, increased heart rate recovery time and phagocytosis activity coinciding with the highest tissue concentrations of some trace metals, polycyclic aromatic hydrocarbons and organotins. At station G1 the highest organochlorine pesticide concentration was recorded as well as elevations in glutathione S-transferase activity, thiamine content and low lysosomal membrane stability. Significant variability in the geno- and cytotoxic responses and bioenergetic status was also observed at the different caging stations. The results obtained suggest that different chemical mixtures present in the study areas cause variable biological response patterns in organisms.
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  • 87
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    A second-order accurate in time IMplicit–EXplicit (IMEX) integration scheme for sea ice dynamics (2014)
    Elsevier
    In:  EPIC3Journal of Computational Physics, Elsevier, 263, pp. 375-392, ISSN: 0021-9991
    Details
    Publication Date: 2019-07-17
    Description: Current sea ice models use numerical schemes based on a splitting in time between the momentum and continuity equations. Because the ice strength is explicit when solving the momentum equation, this can create unrealistic ice stress gradients when using a large time step. As a consequence, noise develops in the numerical solution and these models can even become numerically unstable at high resolution. To resolve this issue, we have implemented an iterated IMplicit–EXplicit (IMEX) time integration method. This IMEX method was developed in the framework of an already implemented Jacobian-free Newton–Krylov solver. The basic idea of this IMEX approach is to move the explicit calculation of the sea ice thickness and concentration inside the Newton loop such that these tracers evolve during the implicit integration. To obtain second-order accuracy in time, we have also modified the explicit time integration to a second-order Runge–Kutta approach and by introducing a second-order backward difference method for the implicit integration of the momentum equation. These modifications to the code are minor and straightforward. By comparing results with a reference solution obtained with a very small time step, it is shown that the approximate solution is second-order accurate in time. The new method permits to obtain the same accuracy as the splitting in time but by using a time step that is 10 times larger. Results show that the second-order scheme is more than five times more computationally efficient than the splitting in time approach for an equivalent level of error.
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  • 88
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    A laboratory study of ikaite (CaCO3·6H2O) precipitation as a function of pH, salinity, temperature and phosphate concentration (2014)
    Elsevier
    In:  EPIC3Marine Chemistry, Elsevier, 162, pp. 10-18, ISSN: 0304-4203
    Details
    Publication Date: 2014-07-30
    Description: Ikaite (CaCO3·6H2O) has only recently been discovered in sea ice, in a study that also provided first direct evidence of CaCO3 precipitation in sea ice. However, little is as yet known about the impact of physico-chemical processes on ikaite precipitation in sea ice. Our study focused on how the changes in pH, salinity, temperature and phosphate (PO4) concentration affect the precipitation of ikaite. Experiments were set up at pH from 8.5 to 10.0, salinities from 0 to 105 (in both artificial seawater (ASW) and NaCl medium), temperatures from 0 to −4 °C andPO4 concentrations from0 to 50 μmol kg−1. The results show that in ASW, calcium carbonate was precipitated as ikaite under all conditions. In the NaCl medium, the precipitates were ikaite in the presence of PO4 and vaterite in the absence of PO4. The onset time (τ) at which ikaite precipitation started, decreased nonlinearly with increasing pH. In ASW, τ increased with salinity. In the NaCl medium, τ first increased with salinity up to salinity 70 and subsequently decreased with a further increase in salinity; it was longer in ASW than in the NaCl medium under the same salinity. τ did not vary with temperature or PO4 concentration. These results indicate that ikaite is very probably the only phase of calcium carbonate formed in sea ice. PO4 is not, as previously postulated, crucial for ikaite formation in sea ice. The change in pH and salinity is the controlling factor for ikaite precipitation in sea ice. Within the ranges investigated in this study, temperature and PO4 concentration do not have a significant impact on ikaite precipitation.
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  • 89
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    Factors influencing particulate lipid production in the East Atlantic Ocean. (2014)
    Elsevier
    In:  EPIC3Deep-Sea Research I, Elsevier, 89, pp. 56-67, ISSN: 0967-0637
    Details
    Publication Date: 2014-05-21
    Description: Extensive analyses of particulate lipids and lipid classes were conducted to gain insight into lipid production and related factors along the biogeochemical provinces of the Eastern Atlantic Ocean. Data are supported by particulate organic carbon (POC), chlorophyll a (Chl a), phaeopigments, Chl a concentrations and carbon content of eukaryotic micro-, nano- and picophytoplankton, including cell abundances for the latter two and for cyanobacteria and prokaryotic heterotrophs. We focused on the productive ocean surface (2 m depth and deep Chl a maximum (DCM)). Samples from the deep ocean provided information about the relative reactivity and preservation potential of particular lipid classes. Surface and DCM particulate lipid concentrations (3.5–29.4 μg L−1) were higher than in samples from deep waters (3.2–9.3 μg L−1) where an increased contribution to the POC pool was observed. The highest lipid concentrations were measured in high latitude temperate waters and in the North Atlantic Tropical Gyral Province (13–25°N). Factors responsible for the enhanced lipid synthesis in the eastern Atlantic appeared to be phytoplankton size (micro, nano, pico) and the low nutrient status with microphytoplankton having the most expressed influence in the surface and eukaryotic nano- and picophytoplankton in the DCM layer. Higher lipid to Chl a ratios suggest enhanced lipid biosynthesis in the nutrient poorer regions. The various lipid classes pointed to possible mechanisms of phytoplankton adaptation to the nutritional conditions. Thus, it is likely that adaptation comprises the replacement of membrane phospholipids by non-phosphorus containing glycolipids under low phosphorus conditions. The qualitative and quantitative lipid compositions revealed that phospholipids were the most degradable lipids, and their occurrence decreased with increasing depth. In contrast, wax esters, possibly originating from zooplankton, survived downward transport probably due to the fast sinking rate of particles (fecal pellets). The important contribution of glycolipids in deep waters reflected their relatively stable nature and degradation resistance. A lipid-based proxy for the lipid degradative state (Lipolysis Index) suggests that many lipid classes were quite resistant to degradation even in the deep ocean.
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  • 90
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    An assessment of global and regional sea level for years 1993–2007 in a suite of interannual CORE-II simulations (2014)
    Elsevier
    In:  EPIC3Ocean Modelling, Elsevier, 78, pp. 35-89, ISSN: 1463-5003
    Details
    Publication Date: 2014-05-26
    Description: We provide an assessment of sea level simulated in a suite of global ocean-sea ice models using the interannual CORE atmospheric state to determine surface ocean boundary buoyancy and momentum fluxes. These CORE-II simulations are compared amongst themselves as well as to observation-based estimates. We focus on the final 15 years of the simulations (1993–2007), as this is a period where the CORE-II atmospheric state is well sampled, and it allows us to compare sea level related fields to both satellite and in situ analyses. The ensemble mean of the CORE-II simulations broadly agree with various global and regional observation-based analyses during this period, though with the global mean thermosteric sea level rise biased low relative to observation-based analyses. The simulations reveal a positive trend in dynamic sea level in the west Pacific and negative trend in the east, with this trend arising from wind shifts and regional changes in upper 700 m ocean heat content. The models also exhibit a thermosteric sea level rise in the subpolar North Atlantic associated with a transition around 1995/1996 of the North Atlantic Oscillation to its negative phase, and the advection of warm subtropical waters into the subpolar gyre. Sea level trends are predominantly associated with steric trends, with thermosteric effects generally far larger than halosteric effects, except in the Arctic and North Atlantic. There is a general anti-correlation between thermosteric and halosteric effects for much of the World Ocean, associated with density compensated changes.
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  • 91
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    Morphological and molecular characterization of three new Azadinium species (Amphidomataceae, Dinophyceae) from the Irminger Sea (2014)
    Elsevier
    In:  EPIC3Protist, Elsevier, 165(4), pp. 417-444, ISSN: 1434-4610
    Details
    Publication Date: 2014-06-11
    Description: Some species of planktonic Azadinium produce azaspiracids (AZAs), a group of lipophilic phycotoxins causing human poisoning after mussel consumption. We describe three new species from the North Atlantic, all of which shared the same Kofoidean plate pattern characteristic for Azadinium: Po, cp, X, 4´, 3a, 6´´, 6C, 5S, 6´´´, 2´´´´. Azadinium trinitatum sp. nov. was mainly characterized by the presence of an antapical spine and by the position of the ventral pore at the left distal end of the pore plate in a cavity of plate 1´. Azadinium cuneatum sp. nov. had a conspicuously formed first apical plate, which was asymmetrically elongated and tapered on its left lateral side with a ventral pore located at the tip of this elongated 1´ plate. Azadinium concinnum sp. nov. was of particular small size (〈 10 µm) and characterized by an anteriorly elongated anterior sulcal plate and by large and symmetric precingular plates. The ventral pore was located inside the apical pore plate on the cells’ right lateral side. Molecular phylogenetics as inferred from concatenated SSU, ITS, and LSU sequence data supported the distinctiveness of the three new species. None of the new species produced any known AZAs in measurable amounts.
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  • 92
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    When shape matters: strategies of different Antarctic ascidians morphotypes to deal with sedimentation (2014)
    Elsevier
    In:  EPIC3Marine Environmental Research, Elsevier, 99, pp. 179-187, ISSN: 0141-1136
    Details
    Publication Date: 2014-09-25
    Description: Climate change leads to increased melting of tidewater glaciers in theWestern Antarctic Peninsula region and sediment bearing glacial melt waters negatively affects filter feeding species as solitary ascidians. In previous work the erect-forms Molgula pedunculata and Cnemidocarpa verrucosa (Order Stolidobranchiata) appeared more sensitive than the flat form Ascidia challengeri (Order Phlebobranchiata). Sedimentation exposure is expected to induce up-regulation of anaerobic metabolism by obstructing the organs of gas exchange (environmental hypoxia) or causes enhanced squirting activity (functional hypoxia). In this study we evaluated the possible relationship between ascidian morphotype and their physiological response to sedimentation. Together with some behavioural observations, we analysed the response of anaerobic metabolic parameters (lactate formation and glycogen consumption) in different tissues of three Antarctic ascidians, exposed to high sediment concentrations (200 mgL�1). The results were compared to experimental hypoxia (10% pO2) and exercise (induced muscular contraction) effects, in order to discriminate the effect of sediment on each species and morpho-type (erect vs. flat forms). Our results suggest that the styled (erect) C. verrucosa increases muscular squirting activity in order to expulse excessive material, while the flat-form A. challengeri reacts more passively by down-regulating its aerobic metabolism under sediment exposure. Contrary, the erect ascidian M. pedunculata did not show any measurable response to the treatments, indicating that filtration and ingestion activities were not reduced or altered even under high sedimentation (low energetic material) which could be disadvantageous on the long-term and could explain why M. pedunculata densities decline in the study area.
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  • 93
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    Indications for algae-degrading benthic microbial communities in deep-sea sediments along the Antarctic Polar Front (2014)
    Elsevier
    In:  EPIC3Deep Sea Research Part II: Topical Studies in Oceanography, Elsevier, 108, pp. 6-16, ISSN: 0967-0645
    Details
    Publication Date: 2014-11-11
    Description: Phytoplankton blooms in surface waters of the oceans are known to influence the food web and impact microbial as well as zooplankton communities. Numerous studies have investigated the fate of phytoplankton-derived organic matter in surface waters and shelf sediments, however, little is known about the effect of sinking algal biomass on microbial communities in deep-sea sediments. Here, we analyzed sediments of four regions in the Southern Atlantic Ocean along the Antarctic Polar Front that had different exposures to phytoplankton bloom derived organic matter. We investigated the microbial communities in these sediments using high-throughput sequencing of 16S rRNA molecules to determine microorganisms that were active and catalyzed reporter deposition fluorescence in situ hybridization to infer their abundance and distribution. The sediments along the Antarctic Polar Front harbored microbial communities that were highly diverse and contained microbial clades that seem to preferably occur in regions of high primary productivity. We showed that organisms affiliated with the gammaproteobacterial clade NOR5/OM60, which is known from surface waters and coastal sediments, thrive in the deep-sea. Benthic deep-sea NOR5 were abundant, diverse, distinct from pelagic NOR5 and likely specialized on the degradation of phytoplankton-derived organic matter, occupying a similar niche as their pelagic relatives. Algal detritus seemed to not only fuel the benthic microbial communities of large areas in the deep-sea, but also to influence communities locally, as we found a peak in Flavobacteriaceae-related clades that also include degraders of algal biomass. The results strongly suggest that phytoplankton-derived organic matter was rapidly exported to the deep-sea, nourished distinct benthic microbial communities and seemed to be the main energy source for microbial life in the seafloor of vast abyssal regions along the Antarctic Polar Front.
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  • 94
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    Water column structure and statistics of Denmark Strait Overflow Water cyclones (2014)
    Elsevier
    In:  EPIC3Deep Sea Research Part I: Oceanographic Research Papers, Elsevier, 84, pp. 110-126, ISSN: 0967-0637
    Details
    Publication Date: 2014-04-04
    Description: Data from seven moorings deployed across the East Greenland shelfbreak and slope 280 km downstream of Denmark Strait are used to investigate the characteristics and dynamics of Denmark Strait Overflow Water (DSOW) cyclones. On average, a cyclone passes the mooring array every other day near the 900 m isobath, dominating the variability of the boundary current system. There is considerable variation in both the frequency and location of the cyclones on the slope, but no apparent seasonality. Using the year-long data set from September 2007 to October 2008, we construct a composite DSOW cyclone that reveals the average scales of the features. The composite cyclone consists of a lens of dense overflow water on the bottom, up to 300 m thick, with cyclonic flow above the lens. The azimuthal flow is intensified in the middle and upper part of the water column and has the shape of a Gaussian eddy with a peak depth-mean speed of 0.22 m/s at a radius of 7.8 km. The lens is advected by the mean flow of 0.27 m/s and self propagates at 0.45 m/s, consistent with the topographic Rossby wave speed and the Nof speed. The total translation velocity along the East Greenland slope is 0.72 m/s. The self-propagation speed exceeds the cyclonic swirl speed, indicating that the azimuthal flow cannot kinematically trap fluid in the water column above the lens. This implies that the dense water anomaly and the cyclonic swirl velocity are dynamically linked, in line with previous theory. Satellite sea surface temperature (SST) data are investigated to study the surface expression of the cyclones. Disturbances to the SST field are found to propagate less quickly than the in-situ DSOW cyclones, raising the possibility that the propagation of the SST signatures is not directly associated with the cyclones.
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  • 95
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    New tools for the reconstruction of Pleistocene Antarctic sea ice (2014)
    Elsevier
    In:  EPIC3Palaeogeography, Palaeoclimatology, Palaeoecology, Elsevier, 399, pp. 260-283, ISSN: 0031-0182
    Details
    Publication Date: 2014-05-06
    Description: Based on the quantitative analysis of diatom assemblages preserved in 274 surface sediment samples recovered in the Pacific, Atlantic and western Indian sectors of the Southern Ocean we have defined a new reference database for quantitative estimation of late-middle Pleistocene Antarctic sea ice fields using the transfer function technique. The Detrended Canonical Analysis (DCA) of the diatom data set points to a unimodal distribution of the diatom assemblages. Canonical Correspondence Analysis (CCA) indicates that not only winter sea ice (WSI) but also summer sea surface temperature (SSST) represent the most prominent environmental variables that control the spatial species distribution. To test the applicability of transfer functions for sea ice reconstruction in terms of concentration and occurrence probability we applied four different methods, the Imbrie and Kipp Method (IKM), the Modern Analog Technique (MAT), Weighted Averaging (WA), and Weighted Averaging Partial Least Squares (WAPLS), using logarithm-transformed diatom data and satellite-derived (1981-2010) sea ice data as a reference. The best performance for IKM results was obtained using a subset of 172 samples with 28 diatom taxa/taxa groups, quadratic regression and a three-factor model (IKM-D172/28/3q) resulting in root mean square errors of prediction (RMSEP) of 7.27% and 11.4% for WSI and summer sea ice (SSI) concentration, respectively. MAT estimates were calculated with different numbers of analogs (4, 6) using a 274-sample/28-taxa reference data set (MAT-D274/28/4an, -6an) resulting in RMSEP´s ranging from 5.52% (4an) to 5.91% (6an) for WSI as well as 8.93% (4an) to 9.05% (6an) for SSI. WA and WAPLS performed less well with the D274 data set, compared to MAT, achieving WSI concentration RMSEP´s of 9.91% with WA and 11.29% with WAPLS, recommending the use of IKM and MAT. The application of IKM and MAT to surface sediment data revealed strong relations to the satellite-derived winter and summer sea ice field. Sea ice reconstructions performed on an Atlantic- and a Pacific Southern Ocean sediment core, both documenting sea ice variability over the past 150,000 years (MIS 1 – MIS 6), resulted in similar glacial/interglacial trends of IKM and MAT-based sea-ice estimates. On the average, however, IKM estimates display smaller WSI and slightly higher SSI concentration and probability at lower variability in comparison with MAT. This pattern is a result of different estimation techniques with integration of WSI and SSI signals in one single factor assemblage by applying IKM and selecting specific single samples, thus keeping close to the original diatom database and included variability, by MAT. In contrast to the estimation of WSI, reconstructions of past SSI variability remains weaker. Combined with diatom-based estimates, the abundance and flux pattern of biogenic opal represents an additional indication for the WSI and SSI extent.
    Repository Name: EPIC Alfred Wegener Institut
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  • 96
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    Spatial and seasonal population dynamics of sympatric Jassa species (Crustacea, Amphipoda) (2014)
    Elsevier
    In:  EPIC3Journal of Experimental Marine Biology and Ecology, Elsevier, 459, pp. 8-16, ISSN: 0022-0981
    Details
    Publication Date: 2014-06-02
    Description: Marine fouling communities are often characterised by dense aggregations of tube-building amphipod species of the genus Jassa. Although some species of this genus coexist in high densities, the development and relationships of sympatric populations are largely unknown. The current field study tested for the effects of exposure duration, seasonality and spatial heterogeneity on community composition, population structure and recruitment of three coexisting Jassa species. The establishment and succession of Jassa-dominated fouling communities on artificial substratum (PVC panels) were studied over two one-year periods off the island of Helgoland (German Bight, North Sea). At different seasonal times, and for different periods of time, panels were exposed at three stations: an exposed station (near water surface), a benthic station in 10 m water depth, and a sheltered station (near water surface). Jassa falcata was the dominant species at the benthic station in 10 m water depth, whereas Jassa marmorata and Jassa herdmani were more abundant on panels which were positioned near the water surface (exposed and sheltered station). The two latter species showed higher abundances at the exposed than at the sheltered station, although J. marmorata was always clearly the dominant species. The differences in the spatial distribution patterns of the three species may partly result from direct interspecific competition for space. Populations of all three Jassa species exhibited strong temporal changes in both abundances and population structure (sex ratio, proportions of reproductively active individuals, male morphs), most likely caused by seasonal factors. Rapid colonisation of free artificial surfaces was observed nearly throughout the year. Intensity of colonisation, however, followed a distinct seasonal pattern with a maximum in the summer months. Recruitment probably occurred via drifting juveniles which originated from amphipod communities in the surroundings. The observed differences among the species may mainly reflect adaptations to different environmental conditions. These differences, however, may also contribute to a stable long-term coexistence via some degree of resource partitioning along with ‘intermediate disturbance’ events.
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  • 97
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    Predictive habitat modelling of humpback (Megaptera novaeangliae) and Antarctic minke (Balaenoptera bonaerensis) whales in the Southern Ocean as a planning tool for seismic surveys (2014)
    Elsevier
    In:  EPIC3Deep Sea Research Part I: Oceanographic Research Papers, Elsevier, 91, pp. 101-114, ISSN: 0967-0637
    Details
    Publication Date: 2014-08-18
    Description: Seismic surveys are frequently a matter of concern regarding their potentially negative impacts on marine mammals. In the Southern Ocean, which provides a critical habitat for several endangered cetacean species, seismic research activities are undertaken at a circumpolar scale. In order to minimize impacts of these surveys, pre-cruise planning requires detailed, spatio-temporally resolved knowledge on the likelihood of encountering these species in the survey area. In this publication we present predictive habitat modelling as a potential tool to support decisions for survey planning. We associated opportunistic sightings (2005–2011) of humpback (Megaptera novaeangliae, N=93) and Antarctic minke whales (Balaenoptera bonaerensis, N=139) with a range of static and dynamic environmental variables. A maximum entropy algorithm (Maxent) was used to develop habitat models and to calculate daily basinwide/circumpolar prediction maps to evaluate how species-specific habitat conditions evolved throughout the spring and summer months. For both species, prediction maps revealed considerable changes in habitat suitability throughout the season. Suitable humpback whale habitat occurred predominantly in ice-free areas, expanding southwards with the retreating sea ice edge, whereas suitable Antarctic minke whale habitat was consistently predicted within sea ice covered areas. Daily, large-scale prediction maps provide a valuable tool to design layout and timing of seismic surveys as they allow the identification and consideration of potential spatio-temporal hotspots to minimize potential impacts of seismic surveys on Antarctic cetacean species.
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  • 98
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    New constraints on the timing of West Antarctic Ice Sheet retreat in the eastern Amundsen Sea since the Last Glacial Maximum (2014)
    Elsevier
    In:  EPIC3Global and Planetary Change, Elsevier, 122, pp. 224-237, ISSN: 0921-8181
    Details
    Publication Date: 2018-08-10
    Description: Glaciers flowing into the Amundsen Sea Embayment (ASE) account for 〉35% of the total discharge of the West Antarctic Ice Sheet (WAIS) and have thinned and retreated dramatically over the past two decades. Here we present detailed marine geological data and an extensive new radiocarbon dataset from the eastern ASE in order to constrain the retreat of the WAIS since the Last Glacial Maximum (LGM) and assess the significance of these recent changes. Our dating approach, relying mainly on the acid insoluble organic (AIO) fraction, utilises multi-proxy analyses of the sediments to characterise their lithofacies and determine the horizon in each core that would yield the most reliable age for deglaciation. In total, we dated 69 samples and show that deglaciation of the outer shelf was underway before 20,600 calibrated years before present (cal. yr BP), reaching the mid-shelf by 13,575 cal. yr BP and the inner shelf to within c.150 km of the present grounding line by 10,615 cal. yr BP. The timing of retreat is broadly consistent with previously published radiocarbon dates on biogenic carbonate from the eastern ASE as well as AIO 14C ages from the western ASE and provides new constraints for ice sheet models. The overall retreat trajectory – slow on the outer shelf, more rapid from the middle to inner shelf – clearly highlights the importance of reverse bedslopes in controlling phases of accelerated groundling line retreat. Despite revealing these broad scale trends, the current dataset does not capture detailed changes in ice flow, such as stillstands during grounding line retreat (i.e., deposition of grounding zone wedges) and possible readvances as depicted in the geomorphological record.
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  • 99
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    A community-based geological reconstruction of Antarctic Ice Sheet deglaciation since the Last Glacial Maximum (2014)
    Elsevier
    In:  EPIC3Quaternary Science Reviews, Elsevier, 100, pp. 1-9, ISSN: 0277-3791
    Details
    Publication Date: 2018-08-10
    Description: The Weddell Sea sector is one of the main formation sites for Antarctic Bottom Water and an outlet for about one fifth of Antarctica’s continental ice volume. Over the last few decades, studies on glacialegeological records in this sector have provided conflicting reconstructions of changes in ice-sheet extent and ice-sheet thickness since the Last Glacial Maximum (LGM at ca 23e19 calibrated kiloyears before present, cal ka BP). Terrestrial geomorphological records and exposure ages obtained from rocks in the hinterland of the Weddell Sea, ice-sheet thickness constraints from ice cores and some radiocarbon dates on offshore sediments were interpreted to indicate no significant ice thickening and locally restricted grounding-line advance at the LGM. Other marine geological and geophysical studies concluded that subglacial bedforms mapped on theWeddell Sea continental shelf, subglacial deposits and sediments over-compacted by overriding ice recovered in cores, and the few available radiocarbon ages from marine sediments are consistent with major ice-sheet advance at the LGM. Reflecting the geological interpretations, different icesheet models have reconstructed conflicting LGM ice-sheet configurations for the Weddell Sea sector. Consequently, the estimated contributions of ice-sheet build-up in the Weddell Sea sector to the LGM sealevel low-stand of w130 m vary considerably. In this paper, we summarise and review the geological records of past ice-sheet margins and past icesheet elevations in the Weddell Sea sector. We compile marine and terrestrial chronological data constraining former ice-sheet size, thereby highlighting different levels of certainty, and present two alternative scenarios of the LGM ice-sheet configuration, including time-slice reconstructions for post- LGM grounding-line retreat. Moreover, we discuss consistencies and possible reasons for inconsistencies between the various reconstructions and propose objectives for future research. The aim of our study is to provide two alternative interpretations of glacialegeological datasets on Antarctic Ice- Sheet History for the Weddell Sea sector, which can be utilised to test and improve numerical icesheet models
    Repository Name: EPIC Alfred Wegener Institut
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  • 100
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    Holocene sea-surface temperature variability in the Chilean fjord region (2014)
    Elsevier
    In:  EPIC3Quaternary Research, Elsevier, 82(2), pp. 342-353, ISSN: 0033-5894
    Details
    Publication Date: 2014-12-16
    Description: Here we provide three new Holocene (11–0 cal ka BP) alkenone-derived sea surface temperature (SST) records from the southernmost Chilean fjord region (50–53°S). SST estimates may be biased towards summer temperature in this region, as revealed by a large set of surface sediments. The Holocene records show consistently warmer than present-day SSTs except for the past ~ 0.6 cal ka BP. However, they do not exhibit an early Holocene temperature optimum as registered further north off Chile and in Antarctica. This may have resulted from a combination of factors including decreased inflow of warmer open marine waters due to lower sea-level stands, enhanced advection of colder and fresher inner fjord waters, and stronger westerly winds. During the mid-Holocene, pronounced short-term variations of up to 2.5°C and a cooling centered at ~ 5 cal ka BP, which coincides with the first Neoglacial glacier advance in the Southern Andes, are recorded. The latest Holocene is characterized by two pronounced cold events centered at ~ 0.6 and 0.25 cal ka BP, i.e., during the Little Ice Age. These cold events have lower amplitudes in the offshore records, suggesting an amplification of the SST signal in the inner fjords.
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