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  • growth  (378)
  • 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
  • 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • Cambridge University Press  (3)
  • American Association for the Advancement of Science
  • American Institute of Physics (AIP)
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  • 1
    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)
    Type: article
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  • 2
    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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  • 3
    Publication Date: 2017-04-04
    Description: The southern New England Orogen (NEO) in eastern Australia is characterized by tight curvatures (oroclines), but the exact geometry of the oroclines and their kinematic evolution are controversial. Here we present new data on the anisotropy ofmagnetic susceptibility (AMS), which provide a petrofabric proxy for the finite strain associated with the oroclines. We focus on a series of preoroclinal Devonian-Carboniferous fore-arc basin rocks, which are aligned parallel to the oroclinal structure, and by examining structural domains, we test whether or not the magnetic fabric is consistent with the strain axes. AMS data show a first-order consistency with the shape of the oroclines, characterized, in most of structural domains, by subparallelism between magnetic lineations, “structural axis” and bedding. With the exception of the Gresford and west Hastings domains, our results are relatively consistent with the existence of the Manning and Nambucca (Hastings) Oroclines. Reconstruction of magnetic lineations to a prerotation (i.e., pre–late Carboniferous) stage, considering available paleomagnetic results, yields a consistent and rather rectilinear NE-SW predeformation fore-arc basin. This supports the validity of AMS as a strain proxy in complex orogens, such as the NEO. In the Hastings Block, magnetic lineations are suborthogonal to bedding, possibly indicating a different deformational history with respect to the rest of the NEO.
    Description: Published
    Description: 2261–2282
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: AMS data, magnetic fabric, oroclines ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.01. Continents ; 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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  • 4
    Publication Date: 2017-04-04
    Description: We report the paleomagnetic and magnetic fabric results of 58 sites from Cretaceous-Miocene marine and continental strata from the Eastern Cordillera (EC) and the Cucuta zone, at the junction between the Santander Massif and the Merida Andes of Colombia. The EC is an intracontinental doubly vergent range inverting a Triassic to Early Cretaceous rift zone. Twenty-three sites reveal nonsystematic tectonic rotations, including unrotated areas of the EC range with respect to stable South America. Our data show that the EC inverted a NNE oriented rift zone and that the orientation of the Mesozoic rift and the mountain chain roughly correspond. Interestingly, magnetic lineations from anisotropy of magnetic susceptibility analysis do not trend parallel to the chain but rather are oblique to the main orogenic trend. By also considering GPS evidence of a ~1 cm/yr ENE displacement of central western Colombia accommodated by the EC, we suggest that the Miocene-Recent deformation event of this belt arises from ENE oblique convergence reactivating a NNE oriented rift zone. Oblique shortening was likely partitioned into pure dip-slip shear characterizing thick-skinned frontal thrust sheets (well known along both chain fronts) and by range-parallel right-lateral strike-slip faults, which have not been identified yet, but likely exist in the axial part of the EC. Finally, the 35° ± 9° clockwise rotation observed in four post-Miocene magnetically overprinted sites from the Cucuta zone reflects late Cenozoic and ongoing right-lateral strike-slip displacement occurring along faults parallel to the Boconó fault system, possibly connected with the right-lateral faults inferred to exist along the axial part of the EC.
    Description: Published
    Description: 2233–2260
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Paleomagnetism, magnetic fabric, Eastern Cordillera ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
    Publication Date: 2017-04-04
    Description: One of the main challenges of paleomagnetic research is to obtain high-resolution geomagnetic field intensity reconstructions. For the last millennia, these reconstructions are mostly based on archeomagnetic data. However, the quality of the intensity data available in the databases is very variable, and the high scatter observed in the records clearly suggests that some of them might not be reliable. In this work we investigate how the geomagnetic field intensity reconstructions and, hence, our present knowledge of the geomagnetic field in the past, are affected by the quality of the data selected for modeling the Earth’s magnetic field. For this purpose we rank the European archeointensity data in four quality categories following widely accepted paleomagnetic criteria based on the methodology used during the laboratory treatment of the samples and on the number of specimens retained to calculate the mean intensities. Four geomagnetic field regional models have been implemented by applying the revised spherical cap harmonic analysis to these four groups of input data. Geomagnetic field models strongly depend on the used data set. The model built using all the available data (without any preselection) appears to be the less accurate, indicating some internal inconsistencies of the data set. In addition, some features of this model are clearly dominated by the less reliable archeointensity data, suggesting that such features might not reflect real variations of the past geomagnetic field. On the contrary, the regional model built on selected high-quality intensity data shows a very consistent intensity pattern at the European scale, confirming that the main intensity changes observed in Europe in the recent history of the geomagnetic field occurred at the continental scale.
    Description: Published
    Description: 2515–2530
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: open
    Keywords: Geomagnetism ; Paleomagnetism ; Archeomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2017-04-04
    Description: Strong changes in seismic radiation, comparable to those preceding and/or accompanying eruptive activity in recent years, were recorded at Mt. Etna volcano, Italy, from November 2005 to January 2006. The amplitude of volcanic tremor peaked in mid-December 2005 after a continuous, slow increase from August 2005 onwards, during which neither effusive nor paroxysmal activity was observed by volcanologists and alpine guides. During this time span, the centroid locations of volcanic tremor moved towards the surface, more and more clustered below the summit craters. The application of pattern classification analysis based on Self-Organizing Maps and fuzzy clustering to volcanic tremor data highlighted variations in the frequency domain as well. These changes were temporally associated with ground deformation variations, as indicative of a mild inflation of the summit of the volcano, and with a conspicuous increase in the SO2 plume-flux emission. Overall, we interpret this evidence as the result of recharging of the volcanic feeder at depth (〉 3 km below sea level) during which magma did not reach the shallow plumbing system.
    Description: Published
    Description: 4989–5005
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: embargoed_20140606
    Keywords: time series analysis ; volcano seismology ; volcano monitoring ; neural network and fuzzy logic ; seismic tomography ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2017-04-04
    Description: From December 2005 to January 2006, an anomalous degassing episode was observed at Mount Etna, well-correlated with an increase in volcanic tremor, and in the almost complete absence of eruptive activity. In the same period, more than 10,000 very long period (VLP) events were detected. Through moment tensor inversion analyses of the VLP pulses, we obtained quantitative estimates of the volumetric variations associated with these events. This allowed a quantitative investigation of the relationship between VLP seismic activity, volcanic tremor, and gas emission rate at Mount Etna. We found a statistically significant positive correlation between SO2 gas flux and volcanic tremor, suggesting that tremor amplitude can be used as a first-order proxy for the background degassing activity of the volcano. VLP volumetric changes and SO2 gas flux are correlated only for the last part of our observations, following a slight change in the VLP source depth. We calculate that the gas associated with VLP signal genesis contributed less than 5% of the total gas emission. The existence of a linear correlation between VLP and degassing activities indicates a general relationship between these two processes. The effectiveness of such coupling appears to depend upon the particular location of the VLP source, suggesting that conduit geometry might play a significant role in the VLP-generating process. These results are the first report on Mount Etna of a quantitative relationship between the amounts of gas emissions directly estimated through instrumental flux measurements and the quantities of gas mass inferred in the VLP source inversion.
    Description: Published
    Description: 4910-4921
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Very Long Period seismicity ; UV scanners network ; Etna Volcano ; volcano monitoring ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    Publication Date: 2017-10-06
    Description: We report on an extensive paleomagnetic study (36 sites) of the Tuscan Nappe succession from the Northern Apennines Arc, aimed to reconstruct the tectonic evolution of the internal sector of this chain. We analyzed Eocene pelagic foreland ramp deposits (Scaglia Toscana Formation) and Oligocene–lower Miocene siliciclastic turbidites (Macigno and Falterona Formations). Paleomagnetic results show that the internal sector of the Northern Apennines underwent large counterclockwise (CCW) rotations with respect to the Adria-Africa foreland. A decrease in the rotation magnitude was observed from the southern to the northern sector of the arc (from 91 to 36°). This trend is opposite to that observed in the more external units of Northern Apennines and demonstrates that the oroclinal bending model, which has been proposed for the external units of the chain, is not appropriate to explain the evolution of the internal sector of the arc. On the basis of the observed paleomagnetic pattern, we propose a new tectonic model in which the Tuscan and Falterona-Cervarola units in the southern area were first rotated CCW along with the Corsica-Sardinia block during its lower Miocene rotational drifting and were later involved in the main phases of rotational emplacement and translation toward the outermost sector (Umbria domain), thus yielding the final curved shape of the Northern Apennines chain. Data from this study represent the first paleomagnetic evidence of the influence of the Corsica-Sardinia CCW rotation in the Apennines orogenic wedge deformation, in the general framework of the geodynamic evolution of the Central Mediterranean subduction system.
    Description: Published
    Description: 374-392
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: paleomagnetism, Apennines, Tuscany ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2020-12-15
    Description: Long continuous seismic data recorded at five broadband seismic stations during 2006 at Campi Flegrei caldera have been analyzed. Introducing a coarse-grained method, we evaluate the time evolution of amplitude and polarization of the seismic noise in the frequency band common to long-period events. The series are modulated on tidal time scales: the root-mean square is basically dominated by solar contribution, while the azimuth of the polarization vector shows lunar diurnal and semidiurnal constituents. In addition, we find that in the frequency band common to long-period events the azimuths are polarized toward a specific area, suggesting that these persistent oscillations can be induced by the activity of the shallow geothermal reservoir.
    Description: Published
    Description: 2628–2637
    Description: JCR Journal
    Description: restricted
    Keywords: sustained hydrothermal tremor ; Campi Flegrei Caldera ; polarization analysis ; tidal modulation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2017-04-04
    Description: Since the second half of the 1990s, the eruptive activity of Mount Etna has provided evidence that both explosive and effusive eruptions display periodic variations in discharge and eruption style. In this work, a multiparametric approach, consisting of comparing volcanological, geophysical, and geochemical data, was applied to explore the volcano's dynamics during 2009–2011. In particular, temporal and/or spatial variations of seismicity (volcano-tectonic earthquakes, volcanic tremor, and long-period and very long period events), ground deformation (GPS and tiltmeter data), and geochemistry (SO2 flux, CO2 flux, CO2/SO2 ratio) were studied to understand the volcanic activity, as well as to investigate magma movement in both deep and shallow portions of the plumbing system, feeding the 2011 eruptive period. After the volcano deflation, accompanying the onset of the 2008–2009 eruption, a new recharging phase began in August 2008. This new volcanic cycle evolved from an initial recharge phase of the intermediate-shallower plumbing system and inflation, followed by (i) accelerated displacement in the volcano's eastern flank since April 2009 and (ii) renewal of summit volcanic activity during the second half of 2010, culminating in 2011 in a cyclic eruptive behavior with 18 lava fountains from New Southeast Crater (NSEC). Furthermore, supported by the geochemical data, the inversion of ground deformation GPS data and the locations of the tremor sources are used here to constrain both the area and the depth range of magma degassing, allowing reconstructing the intermediate and shallow storage zones feeding the 2011 cyclic fountaining NSEC activity.
    Description: Published
    Description: 3519–3539
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: restricted
    Keywords: Mt Etna ; seismology ; ground deformation ; geochemistry ; volcanology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2017-04-04
    Description: Repeating volcano-tectonic (VT) earthquakes, taking place at Mt. Etna during 1999–2009,were detected and analyzed to investigate their behavior. We found 735 families amounting to 2479 VT earthquakes, representing ~38% of all the analyzed VT earthquakes. The number of VT earthquakes making up the families ranges from 2 to 23. Over 70% of the families comprise 2 or 3 VT earthquakes and only 20 families by more than 10 events. The occurrence lifetime is also highly variable ranging from some minutes to ten years. In particular, more than half of the families have a lifetime shorter than 0.5 day and only ~10% longer than 1 year. On the basis of these results, most of the detected families were considered “burst-type”, i.e., show swarm-like occurrence, and hence their origin cannot be explained by a temporally constant tectonic loading. Indeed, since the analyzed earthquakes take place in a volcanic area, the rocks are affected not only by tectonic stresses related to the fairly steady regional stress field but also by local stresses, caused by the volcano, such as magma batch intrusions/ movements and gravitational loading.We focused on the five groups of families characterized by the longest repeatability over time, namely high number of events and long lifetime, located in the north-eastern, eastern and southern flanks of the volcano. Unlike the first four groups, which similarly to most of the detected families show swarm-like VT occurrences, group “v”, located in the north-eastern sector, exhibits a more “tectonic” behavior with the events making up such a group spread over almost the entire analyzed period. It is clear how both occurrence and slip rates do not remain constant but vary over time, and such changes are time-related to the occurrence of the 2002–2003 eruption. Finally, by FPFIT algorithm a good agreement between directions identified by nodal planes and the earthquake epicentral distribution was generally found.
    Description: Published
    Description: 1223 – 1236
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: repeating earthquakes ; Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publication Date: 2017-04-04
    Description: Stratigraphic, structural, palaeocurrent and palaeomagnetic analyses of Upper Albian deep-water deposits in and around the Deba block (Northern Iberia) are presented. Results indicate an anticlockwise vertical-axis rotation of this block by 35◦ during a maximum time span of c. 1 Ma (Late Albian intra-C. auritus ammonite Subzone). This Albian syndepositional block rotation is interpreted to be the consequence of the coeval activity of conjugatemajor sinistral strike-slip faults and minor (antithetic) dextral strike-slip faults, which border the Deba block. On the base of conservative estimations, a minimum block-rotation rate of 35◦ Ma−1 and a sinistral strike-slip rate of 1.2 kmMa−1 are calculated. As a consequence of the interaction of the rotated Deba block with adjacent nonrotated blocks, its corners experienced coeval transpressive (NW and SE corners) and transtensional deformations (SW and, possibly, NE corners). At the transtensional SW corner, two domal highreflective seismic structures have been recorded and interpreted as high-level magmatic laccoliths. These magmatic intrusions triggered the development of a mineralizing hydrothermal system, which vented to the Late Albian seafloor warm to hot hydrocarbon-rich fluids. Vented hydrocarbon was generated from Albian organic-rich sediments by contact alteration with hydrothermal fluids.
    Description: Published
    Description: 986-1001
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: block rotation ; palaeocurrent ; palaeomagnetism ; Albian ; Basque–Cantabrian Basin ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
    Publication Date: 2017-04-04
    Description: Integration of structural, stratigraphic, and paleomagnetic data from the N–S trending structures of the Ainsa Oblique Zone reveals the kinematics of the major thrust salient in the central Pyrenees. These structures experienced clockwise vertical axis rotations that vary from 70° in the east (Mediano anticline) to 55° in the west (Boltaña anticline). Clockwise vertical axis rotations of 60° to 45° occurred from early Lutetian to late Bartonian when the folds and thrusts of the Ainsa Oblique Zone developed. This vertical axis rotation stage resulted from a difference of about 50 km in the amount of displacement on the Gavarnie thrust and an accompanying change in structural style at crustal scale from the central to the western Pyrenees, related to the NE–SW trending pinch out of Triassic evaporites at its basal detachment. A second rotation event of at least 10° took place since Priabonian, as a result of a greater displacement of the Serres Marginals thrust sheet with respect to the Gavarnie thrust sheet above the Upper Eocene-Oligocene salts. The deduced kinematics demonstrates that the orogenic curvature of the central Pyrenees is a progressive curvature resulting from divergent thrust transport direction. Layer parallel shortening mesostructures and kilometer-scale folds also developed by a progressive curvature related to divergent shortening directions during vertical axis rotation. Rotation space problems were solved by along-strike extension which triggered the formation of transverse extensional faults and diapirs at the outer arcs of structural bends.
    Description: Published
    Description: 1142–1175
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: vertical-axis rotation ; thrust-sheet ; Eocene ; orogen ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2017-04-04
    Description: In this work, waveform variations in repeating volcanotectonic earthquakes occurring from 2001–2009 in the northeastern flank of Mt. Etna were studied. Changes in waveform were found mainly during 2002–2003; and consisted of a decreasing similarity in the coda of events in earthquake families, as revealed by cross-correlation analysis, and delays, increasing proportionally to the lapse time, detected by coda wave interferometry. Such variations, mainly evident at stations located in the north-eastern flank of the volcano, were likely due to medium changes taking place within this region. Localized medium velocity decreases were inferred to occur in 2002–2003, followed by successive increases. The velocity decrease was interpreted as being caused by the opening or enlargement of cracks, produced by intruding magma bodies, intense ground deformation, and/ or VT earthquake activity that accompanied the 2002–2003 Mt. Etna eruption. On the other hand, subsequent velocity increases were interpreted as resulting from healing processes.
    Description: Published
    Description: L18311
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: coda wave interferometry ; Etna ; VT earthquakes ; Pernicana fault ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 15
    Publication Date: 2017-04-04
    Description: One hundred twenty-nine long-period (LP) events, divided into two families of similar events, were recorded by the 50 stations deployed on Mount Etna in the second half of June 2008. During this period lava was flowing from a lateral fracture after a summit Strombolian eruption. In order to understand the mechanisms of these events, we perform moment tensor inversions. Inversions are initially kept unconstrained to estimate the most likely mechanism. Numerical tests show that unconstrained inversion leads to reliable moment tensor solutions because of the close proximity of numerous stations to the source positions. However, single forces cannot be accurately determined as they are very sensitive to uncertainties in the velocity model. Constrained inversions for a crack, a pipe or an explosion then allow us to accurately determine the structural orientations of the source mechanisms. Both numerical tests and LP event inversions emphasise the importance of using stations located as close as possible to the source. Inversions for both families show mechanisms with a strong volumetric component. These events are most likely generated by cracks striking SW–NE for both families and dipping 70° SE (family 1) and 50° NW (family 2). For family 1 events, the crack geometry is nearly orthogonal to the dikelike structure along which events are located, while for family 2 the location gave two pipelike bodies that belong to the same plane as the crack mechanism. The orientations of the cracks are consistent with local tectonics, which shows a SW–NE weakness direction. The LP events appear to be a response to the lava fountain occurring on 10 May 2008 as opposed to the flank lava flow.
    Description: Published
    Description: B01304
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Etna Volcano ; long-period events ; source mechanism ; location ; plumbing systems ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
    Publication Date: 2017-04-03
    Description: SPY is a Matlab algorithm that analyzes seismic waveforms in a semiautomatic way, providing estimates of the two observables of the anisotropy: the shear-wave splitting parameters. We chose to exploit those computational processes that require less intervention by the user, gaining objectivity and reliability as a result. The algorithm joins the covariance matrix and the cross-correlation techniques, and all the computation steps are interspersed by several automatic checks intended to verify the reliability of the yields. The resulting semiautomation generates two new advantages in the field of anisotropy studies: handling a huge amount of data at the same time, and comparing different yields. From this perspective, SPY has been developed in the Matlab environment, which is widespread, versatile, and user-friendly. Our intention is to provide the scientific community with a new monitoring tool for tracking the temporal variations of the crustal stress field.
    Description: Published
    Description: 138-145
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: Crustal anisotropy ; Waveform analysis ; Seismic monitoring ; Stress field ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 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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  • 17
    Publication Date: 2017-04-03
    Description: An integrated bio-, magneto- and cyclostratigraphic study of the Ypresian/Lutetian (Early/Middle Eocene) transition along the Otsakar section resulted in the identification of the C22n/C21r chron boundary and of the calcareous nannofossil CP12a/b zonal boundary; the latter is the main correlation criterion of the Lutetian Global Stratotype Section and Point (GSSP) recently defined at Gorrondatxe (Basque Country). By counting precession-related mudstone–marl couplets of 21 ka, the time lapse between both events was calculated to be 819 ka. This suggests that the age of the CP12a/b boundary, and hence that of the Early/Middle Eocene boundary, is 47.76 Ma, 250 ka younger than previously thought. This age agrees with, and is supported by, estimates from Gorrondatxe based on the time lapse between the Lutetian GSSP and the C21r/C21n boundary. The duration of Chron C21r is estimated at 1.326 Ma. Given that the base of the Eocene is dated at 55.8 Ma, the duration of the Early Eocene is 8 Ma, 0.8 Ma longer than in current time scales. The Otsakar results further show that the bases of planktonic foraminiferal zones E8 and P10 are younger than the CP12a/b boundary. The first occurrence of Turborotalia frontosa, being approximately 550 ka older that the CP12a/b boundary, is the planktonic foraminiferal event that lies closest to the Early/Middle Eocene boundary. The larger foraminiferal SBZ12/13 boundary is located close to the CP12a/b boundary and correlates with Chron C21r, not with the C22n/C21r boundary.
    Description: Published
    Description: 442-460
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Eocene ; Ypresian–Lutetian boundary ; biostratigraphy ; magnetostratigraphy ; cyclostratigraphy. ; 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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  • 18
    Publication Date: 2017-04-04
    Description: We present paleomagnetic, rock magnetic and scanning electron microscope data from three upper Messinian stratigraphic sections from the Adana Basin (southern Turkey). The collected samples are from fine-grained units, which were deposited during the Messinian Salinity Crisis (within subchron C3r). Paleomagnetic results reveal an inconsistent polarity record, related to a mixture of magnetite and greigite that hinders determination of a reliable magnetostratigraphy. Three classes of samples are recognized on the basis of paleomagnetic results. The first is characterized by a single magnetization component, with normal polarity, that is stable up to 530–580 C and is carried by magnetite. The second is characterized by a single magnetization component, with reversed polarity, that is stable up to 330–420 C. This magnetization is due to greigite, which developed after formation of slumps and before tectonic tilting of the studied successions. The third is characterized by reversed polarity, which is stable up to 530–580 C. We interpret this component as a primary magnetization carried by fine-grained and magnetically stable detrital magnetite. Results indicate that in the Adana Basin the assumption that a primary magnetization is carried by magnetite, and a magnetic overprint carried by greigite, does not hold because a late magnetic overprint has also been found for magnetite-bearing samples. Our data illustrate the complexity of magnetostratigraphic reconstructions in successions characterized by variable mixtures of magnetic minerals with different magnetic stability that formed at different stages. We demonstrate the need to perform detailed magnetic mineralogy analyses when conducting magnetostratigraphic studies of clay-rich sediments from marine or lacustrine environments.
    Description: Published
    Description: Q10002
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Messinian ; remagnetization ; reversals ; rock and mineral magnetism ; southern Turkey ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2017-04-03
    Description: Among the eruptive styles, the Strombolian activity is one of the more easy to study because of its repetitive behavior. For this reason large amount of data can be comfortably collected. Strombolian volcanoes are like natural laborato- ries repeating the same experiment (individual explosions) many times each day. The development of quantitative models of eruptive dynamics is driven by the comparison of experimental ob- servations and synthetic data obtained through mathemat- ical, numerical or analogue modeling. Since Strombolian activity offers a profuse amount of interesting seismic signals, during the last decades there has been growing attention on seismological techniques aimed at retrieving the conduit geometry and the eruption dynamics from the seismological recordings. One of these techniques, the source function inversion, is able to re- trieve a summary of the forces acting on the volcanic con- duit during the VLP event generation [5]. The comparison of observed source functions with synthetic ones, obtained through numerical modeling, allow us to put constraints on the proposed models. Quantitative models, able to fit seismological observa- tions, are a powerful tool for interpreting seismic record- ings and therefor the seismological monitoring of active volcanoes.
    Description: Published
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: restricted
    Keywords: Strombolian activity ; Slug flow ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 20
    Publication Date: 2017-04-04
    Description: Continuous seismic monitoring plays a key role in the surveillance of the Mt. Etna volcano. Besides earthquakes, which often herald eruptive episodes, the persistent background signal, known as volcanic tremor, provides important information on the volcano status. Changes in the regimes of activity are usually concurrent with variations in tremor characteristics. As continuous recording leads rapidly to the accumulation of large amounts of data, parameter extraction and automated processing become crucial. We propose techniques of unsupervised classification and present a software, named KKAnalysis, developed for this purpose. Essentials of KKAnalysis are demonstrated on tremor data recorded on Mt. Etna during various states of volcanic activity encountered in 2007 and 2008. KKAnalysis is based on MATLAB and combines various unsupervised pattern recognition techniques, in particular self-organizing maps (SOM) and cluster analysis. An early software version was successfully applied to seismic signals recorded on Mt. Etna during the eruption in 2001. Since each situation may require different configurations, we designed KKAnalysis with a specific GUI allowing users to easily modify parameters. All results are given graphically, in screen plots and metafiles (MATLAB and TIF format), as well as in alphanumeric form. The synoptic visualization of results from SOM and cluster analysis facilitates an immediate inspection. The potential of this representation is demonstrated by focusing on data recorded during a flank eruption on May 13, 2008. Changes of tremor characteristics can be clearly identified at a very early stage, well before enhanced volcanic activity becomes visible in the time series. At the same time, data reduction to less than 1% of the original amount is achieved, which facilitates interpretation and storage of the essential information. Running the program in a typical configuration requires computing time less than 1 min, allowing an on-line application for early warning purposes at INGV–Sezione di Catania
    Description: Published
    Description: 953-961
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 5.6. TTC - Attività di Sala Operativa
    Description: JCR Journal
    Description: reserved
    Keywords: Self-Organizing Map ; Cluster Analysis ; K-means ; Fuzzy C-means ; Volcano Seismology ; Volcano Monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 21
    Publication Date: 2017-04-04
    Description: Seismic activity, ground deformation, and soil and fumarole temperatures acquired during 2004–2007 at Vulcano (Aeolian Islands) are analysed and the time relations among the different time series are discussed. Changes in temperature of fumarolic gases took place during four ‘‘anomalous’’ periods (November 2004–March 2005; October 2005–February 2006; August–October 2006; July–December 2007) at the same time as an increasing number of volcano-seismic events. In particular, the temperatures at high temperature vents and at steam heated soil ranged in time from 180 to 440 C and from 20 to 90 C, respectively. The maximum daily number of volcano-seismic events was 57, reached during the second anomalous period. This seismicity, characterised by focal depth generally lower than 1 km below sea level (b.s.l.) and composed of different kinds of events associated to both resonance and shear failure processes, is related to the shallow dynamics of the hydrothermal system. During the analysed period, very few volcano-tectonic earthquakes took place and tilt recordings showed no sharp or important changes. In light of such observations, the increases in both temperature and volcano-seismic events number were associated to increases in the release of gas from a deep and stable magma body, without magma intrusions within the shallow hydrothermal system. Indeed, a greater release of gas from depth leads to increased fluid circulation, that can promote increases in volcano-seismic events number by both fracturing processes and resonance and vibration in cracks and conduits. The different trends observed in the measured geochemical and geophysical series during the anomalous periods can be due to either time changes in the medium permeability or a changing speed of gas release from a deep magma body. Finally, all the observed variations, together with the changing temporal distribution of the different seismic event kinds, suggest that the hydrothermal system at Vulcano can be considered unsteady and dynamic.
    Description: Published
    Description: 167–182
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismolog ; soil and fumarole temperatures ; tilt data ; hydrothermal system ; Vulcano Island ; volcanic unrest ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 22
    Publication Date: 2021-05-17
    Description: Biostratigraphy based on calcareous nannofossils, integrated by magnetostratigraphic, geochronological and isotopic data, allowed establishing a precise chronological framework for the Pleistocene succession within the south-western sector of the Crotone Basin (Calabria, Southern Italy), where the Pliocenee Pleistocene global stratotype section and point is defined, thus demonstrating that sedimentation was quasi-continuous during most of the Lower and Middle Pleistocene. At a large scale, the Pleistocene succession in this sector of the Crotone Basin is characterized by an evident shallowing-upwards trend, showing facies changes from bathyal to shelfal to littoral/continental. However, comparison between adjacent sectors within the investigated area demonstrates that stratigraphic architectures change vastly on very short distances. Our chronological constraints indicate that such changes in sedimentation styles probably occurred in response to differential subsidence rates, which originated tectonically-controlled synsedimentary structures where accommodation space and sediment yield were allotted unevenly. This articulated physiography led to striking differences in the overall thicknesses and organization of Pleistocene stratigraphies and, eventually, to a distinct diachroneity in the first appearance of shallow-marine deposits. In addition, superimposed are complex interplays between regional and local tectonics, eustasy and orbitally-forced climate changes. These interactions have been highlighted by the oxygen isotope stratigraphy established for a part of the studied succession, which is likely to document almost continuously the interval from Marine Isotope Stage (MIS) 26 to MIS 17. In its younger part (post-MIS 17), chronological ties are poor, as the succession is dominated by shallow-water to continental deposits showing a prominent organization into cyclothems. Nevertheless, based on the chronology of the underlying units, it is feasible that basin infill ended during MIS 15-MIS 14 times.
    Description: Published
    Description: 1185-1200
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Pleistocene ; Chronostratigraphy ; Southern Italy ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 23
    Publication Date: 2020-12-15
    Description: Four sediment cores were analysed in order to determine the sedimentary processes associated with the channel-ridge depositional system that characterise the George V Land continental margin on the Wilkes Land. The sedimentary record indicates that the WEGA channel was a dynamic turbiditic system up to M.I.S. 11. After this time, the channel became a lower-energy environment with sediments delivered to the channel through high-density bottom waters that we identify to be the high salinity shelf waters (HSSW) forming on the shelf area. The HSSW entrains the fine-grained sediments of the shelf area and deliver them to the continental rise. The biostratigraphy and facies of the sediments within the WEGA channel indicate that the HSSW down flow was active also during last glacial. The change from a turbiditic system to a lowenergy bottom current system within the WEGA channel likely reflects a different ice-flow pattern, with ice-sheet reaching the continental shelf edge only within the ice trough (ice stream).
    Description: Published
    Description: 909 - 926
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: High salinity shelf water ; Turbidity currents ; Glacio-marine depositional processes ; Marine isotopic stage 11 ; Glacial dynamic changes ; 02. Cryosphere::02.02. Glaciers::02.02.05. Ice dynamics ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 24
    Publication Date: 2012-02-03
    Description: Greigite (Fe3S4) is an authigenic ferrimagnetic mineral that grows as a precursor to pyrite during early diagenetic sedimentary sulfate reduction. It can also grow at any time when dissolved iron and sulfide are available during diagenesis. Greigite is important in paleomagnetic, environmental, biological, biogeochemical, tectonic, and industrial processes. Much recent progress has been made in understanding its magnetic properties. Greigite is an inverse spinel and a collinear ferrimagnet with antiferromagnetic coupling between iron in octahedral and tetrahedral sites. The crystallographic c axis is the easy axis of magnetization, with magnetic properties dominated by magnetocrystalline anisotropy. Robust empirical estimates of the saturation magnetization, anisotropy constant, and exchange constant for greigite have been obtained recently for the first time, and the first robust estimate of the low‐field magnetic susceptibility is reported here. The Curie temperature of greigite remains unknown but must exceed 350°C. Greigite lacks a low‐temperature magnetic transition. On the basis of preliminary micromagnetic modeling, the size range for stable single domain behavior is 17–200 nm for cubic crystals and 17–500 nm for octahedral crystals. Gradual variation in magnetic properties is observed through the pseudo‐single‐domain size range. We systematically document the known magnetic properties of greigite (at high, ambient, and low temperatures and with alternating and direct fields) and illustrate how grain size variations affect magnetic properties. Recognition of this range of magnetic properties will aid identification and constrain interpretation of magnetic signals carried by greigite, which is increasingly proving to be environmentally important and responsible for complex paleomagnetic records, including widespread remagnetizations.
    Description: Published
    Description: RG1002
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: greigite ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 25
    Publication Date: 2017-04-04
    Description: We have found experimental evidence which shows that the volcanic tremor recorded at Deception Island (South Shetland Islands, Antarctica) is a superposition in time of overlapping hybrid events.
    Description: Published
    Description: 3069-3072
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Arrays ; volcanictremor ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 26
    Publication Date: 2017-04-04
    Description: We consider the space–time distribution of seismicity during the 1982–1984 unrest at Campi Flegrei caldera (Italy) where a correlation between seismicity and rate of ground uplift was suggested. In order to investigate this effect, we present a model based on stress transfer from the deformation source responsible for the unrest to potential faults. We compute static stress changes caused by an inflating source in a layered half-space. Stress changes are evaluated on optimally oriented planes for shear failure, assuming a regional stress with horizontal extensional axis trending NNE-SSW. The inflating source is modeled as inferred by previous studies from inversion of geodetic data with the same crustal model here assumed. The magnitude of the regional stress is constrained by imposing an initial condition of “close to failure” to potential faults. The resulting spatial distribution of stress changes is in agreement with observations. We assume that the temporal evolution of ground displacement, observed by a tide-gauge at Pozzuoli, was due mainly to time dependent processes occurring at the inflating source. We approximate this time dependence in piecewise-linear way and we attribute it to each component of average stress-change in the region interested by the observed seismicity. Then we evaluate the effect of a time dependent stressing rate on seismicity, by following the approach indicated by Dieterich (1994) on the basis of the rate- and state-dependent rheology of faults. The seismicity rate history resulting from our model is in general agreement with data during the period 1982– 1984 for reasonable values of unconstrained model-parameters, the initial value of the direct effect of friction and the reference shear stressing rate. In particular, this application shows that a decreasing stressing-rate is effective in damping the seismicity rate.
    Description: Published
    Description: 287-298
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Triggered seismicity ; Volcanic tremor ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 27
    Publication Date: 2017-04-04
    Description: We present results of detailed paleomagnetic investigations on deep!sea cores from sediment drifts located along the Pacific continental margin of the Antarctic Peninsula. High!resolution magnetic measurements on u channel samples provide detailed age models for three cores collected from drift 7, which document an age of 122 ka for the oldest sediments recovered near the drift crest at site SED!07 and a high sedimentation rate (11 cm/kyr) at site SED!12 located close to the Alexander Channel system. Low! and high!temperature magnetic measurements in conjunction with microscopic and mineralogic observations from drifts 4, 5 and 7 indicate that pseudosingle!domain detrital titanomagnetite (partially oxidized and with limited Ti substitution) is the dominant magnetic mineral in the drift sediments. The titanomagnetite occurs in two magnetic forms: (1) a low!coercivity form similar to laboratory!synthesized titanomagnetite and (2) a high!coercivity form (Bcr 〉 60 mT). These two forms vary in amount and stratigraphic distribution across the drifts. We did not find evidence for diagenetic magnetic iron sulfides as has been previously suggested for these drift deposits. The observed change of magnetic mineralogy in sediments deposited during Heinrich events on drift 7 appears to be related to warming periods, which temporarily modified the normal glacial transport pathways of glaciogenic detritus to and along the continental rise and thus resulted in deposition of sediments with a different provenance. Understanding this sediment provenance delivery signature at a wider spatial scale should provide information about ice sheet dynamics in West Antarctica over the last !100 kyr.
    Description: Published
    Description: B06104
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: partially_open
    Keywords: Antarctic Peninsula ; Pacific margin ; sediment drift ; late Pleistocene ; Mineral magnetism ; relative palaeointensity ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 28
    Publication Date: 2017-04-04
    Description: Society’s needs for a network of in situ ocean observing systems cross many areas of earth and marine science. Here we review the science themes that benefit from data supplied from ocean observatories. Understanding from existing studies is fragmented to the extent that it lacks the coherent long-term monitoring needed to address questions at the scales essential to understand climate change and improve geo-hazard early warning. Data sets from the deep sea are particularly rare with long-term data available from only a few locations worldwide. These science areas have impacts on societal health and well-being and our awareness of ocean function in a shifting climate. Substantial efforts are underway to realise a network of open-ocean observatories around European Seas that will operate over multiple decades. Some systems are already collecting high-resolution data from surface, water column, seafloor, and sub-seafloor sensors linked to shore by satellite or cable connection in real or near-real time, along with samples and other data collected in a delayed mode. We expect that such observatories will contribute to answering major ocean science questions including: How can monitoring of factors such as seismic activity, pore fluid chemistry and pressure, and gas hydrate stability improve seismic, slope failure, and tsunami warning? What aspects of physical oceanography, biogeochemical cycling, and ecosystems will be most sensitive to climatic and anthropogenic change? What are natural versus anthropogenic changes? Most fundamentally, how are marine processes that occur at differing scales related? The development of ocean observatories provides a substantial opportunity for ocean science to evolve in Europe. Here we also describe some basic attributes of network design. Observatory networks provide the means to coordinate and integrate the collection of standardised data capable of bridging measurement scales across a dispersed area in European Seas adding needed certainty to estimates of future oceanic conditions. Observatory data can be analysed along with other data such as those from satellites, drifting floats, autonomous underwater vehicles, model analysis, and the known distribution and abundances of marine fauna in order to address some of the questions posed above. Standardised methods for information management are also becoming established to ensure better accessibility and traceability of these data sets and ultimately to increase their use for societal benefit. The connection of ocean observatory effort into larger frameworks including the Global Earth Observation System of Systems (GEOSS) and the Global Monitoring of Environment and Security (GMES) is integral to its success. It is in a greater integrated framework that the full potential of the component systems will be realised.
    Description: Published
    Description: 1-33
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: reserved
    Keywords: Seafloor and water columnobservatories ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate ; 01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models ; 03. Hydrosphere::03.01. General::03.01.07. Physical and biogeochemical interactions ; 03. Hydrosphere::03.01. General::03.01.08. Instruments and techniques ; 03. Hydrosphere::03.03. Physical::03.03.01. Air/water/earth interactions ; 03. Hydrosphere::03.03. Physical::03.03.02. General circulation ; 03. Hydrosphere::03.03. Physical::03.03.03. Interannual-to-decadal ocean variability ; 03. Hydrosphere::03.03. Physical::03.03.05. Instruments and techniques ; 03. Hydrosphere::03.04. Chemical and biological::03.04.01. Biogeochemical cycles ; 03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.04. Ecosystems ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 03. Hydrosphere::03.04. Chemical and biological::03.04.08. Instruments and techniques ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.03. Heat generation and transport ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 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::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.02. Data dissemination::05.02.04. Hydrogeological data ; 05. General::05.08. Risk::05.08.01. Environmental risk ; 05. General::05.08. Risk::05.08.02. Hydrogeological risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 29
    Publication Date: 2020-02-24
    Description: Recent laboratory experiments on Etna basalt have permitted the generation of an extensive catalogue of acoustic emissions (AE) during two key experimental phases. Firstly, AE have been generated during triaxial compressional tests and formation of a complex fracture/damage zone. Secondly, rapid fluid decompression through the damage/shear zone after failure. We report new results from an advanced analysis method using AE spectrograms, allowing us to qualitatively identify high and low frequency events; essentially comparable to seismicity in volcanic areas. Our analysis, for the first time, quantitatively classifies ‘families’ of AE events belonging to the same experimental stage without prior knowledge. We then test the method using the AE catalogue for verification, which is not possible with field data. FFT spectra, obtained from AE, are subdivided into equal log intervals for which a local slope is calculated. Factor analysis has been then applied, in which we use a data matrix of columns representing the variables considered (frequency data averaged in bins) vs. rows indicating each AE data set. Factor analysis shows that the method is very effective and suitable for reducing data complexity, allowing distinct factors to be obtained. We conclude that most of the data variance (information content) can be well represented by three factors only, each one representing a well defined frequency range. Through the factor scores it is possible to represent data in a lower dimension factor space. Classification is then possible by identifying clusters of AE belonging to the same experimental stage. This allows us to propose a deformation/decompression interpretation based solely on the AE frequency analysis and to identify a third type of AE related to fluid movements in the deformation stage.
    Description: Published
    Description: 201-211
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: open
    Keywords: acoustic emissions ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 30
    Publication Date: 2017-04-04
    Description: 129 Long Period (LP) events, divided in two families were recorded by 50 stations deployed on Mount Etna within an eruptive context in the second half of June 2008. In order to understand the mechanisms of these events, we perform moment tensor inversion. Numerical tests show that unconstrained inversion leads to reliable moment tensor solutions because of the close proximity of numerous stations to the source positions. However, single forces cannot be accurately determined as they are very sensitive to uncertainities in the velocity model. These tests emphasize the importance of using stations located as close as possible to the source in the inversion of LP events. Inversion of LP signals is initially unconstrained, in order to estimate the most likely mechanism. Constrained inversions then allow us to accurately determine the structural orientations of the mechanisms. Inversions for both families show mechanisms with strong volumetric components. These events are generated by cracks striking SW-NE for both families and dipping 70± SE (fam. 1) and 50± NW (fam. 2). The geometries of the cracks are different from the structures obtained by the location of these events. The orientation of the cracks is consistent with the local tectonic context on Mount Etna. The LP events seem to be a response to the lava fountain occuring on the 10th of May, 2008.
    Description: In press
    Description: (38)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: Long-Period events ; earthquake source mechanism ; Etna Volcano ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 31
    Publication Date: 2017-04-04
    Description: This paper presents an analysis of seismicity associated with the volcanic activity of Volcàn de Colima (México) and recorded in the period November 2005–April 2006 during a field survey by the Istituto Nazionale di Geofisica e Vulcanologia (INGV)–Osservatorio Vesuviano, the Observatorio Vulcanologico de Colima of Colima University and the Instituto Andaluz de Geofisica, University of Granada. Three different types of volcanic earthquakes have been identified on the basis of their spectral properties: Type A (0.3–1 Hz), Type B (1–5 Hz) and Type C (3–4 Hz). Results of polarization analysis applied to Type A events show a predominance of radial motion, indicating that the wavefield comprises compressional waves (P) and shear waves polarized in the vertical plane (SV), while the signal always begins with a negative polarity. Type A, B and C earthquakes have been located using both a flat layered model and a 3D model including topography. Hypocentre distributions indicate that the source of Type A signals is very shallow and confined to a small volume lying about 1 km below the crater. In contrast, the source of Type B and C events is significantly deeper, with most hypocentres located in a volume of about 1 km3 centred at 2.5–3 km depth. A cluster analysis based on the crosscorrelation among the waveforms of different events recorded at the same station was applied to Type A earthquakes. Only two clusters, which include only a small percentage of events were found, indicating that earthquake families were uncommon during the period of our survey.
    Description: Published
    Description: 887-898
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Colima Volcano ; Long Period Events ; Earthquake location ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 32
    Publication Date: 2017-04-04
    Description: On 16 November 2006, a 1 day long paroxysmal eruption occurred at the summit craters of Mt. Etna volcano. A multiparametric approach, consisting of analyzing infrasonic, seismic, and video camera recordings, was carried out to follow its evolution. Volcanological and geophysical observations identified three eruptive phases. In the first phase, infrasonic and seismic characteristics reflected the highly explosive nature of the activity. Waveform characterization of infrasound events confirmed the activity of the several explosive vents at the summit of Southeast Crater (SEC). During the second phase, results highlighted the decoupling between seismic and infrasonic sources, which was due to the decrease in explosive activity and the reactivation of effusive vents located south of Bocca Nuova and on the saddle between Bocca Nuova and SEC. The third phase was the most intense and was characterized by various volcanic phenomena (pyroclastic flows, jets of dark ash, and white steam). The very high radiated infrasonic energy, together with infrasound event features, led us to infer a gas enrichment of the shallow magma column, preceding by a few minutes and likely related to the pyroclastic flows in the SEC area. After the eruption at SEC, variations in infrasound events related to the activity of Northeast Crater (NEC) were found. The observed spectral changes and the source mechanism modeling of the NEC infrasound events suggest the existence of a link in the plumbing system feeding the two craters.
    Description: Published
    Description: B09301
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; Infrasound ; volcanic tremor ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 33
    Publication Date: 2017-04-04
    Description: On 13 May 2008 an eruptive fissure opened on Mount Etna's eastern flank feeding both explosive activity and lava effusion from multiple vents for about 14 months. During the investigated May-September 2008 eruptive period, infrasound recordings from a 4 station-sparse network allowed tracking of the explosive activity in terms of location and dynamics. In order to focus on activity from the eruptive fissure, the infrasonic events generated by the summit craters were selected by using both spectral features and time delays between pairs of stations and excluded from our analysis. Then, to accurately locate events from the fissure, we used a composite method, based on the semblance and brightness functions. This enabled the study of the co-existence of more than one infrasound source and/or its migration along the eruptive fissure. Hence, results permitted us to discriminate the number of active vents and their location along the fissure even when, due to poor weather conditions, it was not possible to access the vents or carry out direct observations. The eruptive activity was characterised by variations in the number of active vents according to the overall intensity of the eruptive event. Variability of the infrasound waveforms highlighted either that distinct vents produced signals with different waveforms, or that single vents generated different events during distinct periods of time, or finally both the previous phenomena. We applied the strombolian bubble vibration model to model waveform differences and attributed the signal variations to bubble radius changes.
    Description: Published
    Description: 1-11
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; Infrasound ; Infrasonic source location ; explosive activity ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 34
    Publication Date: 2017-11-17
    Description: Island (Antarctica), recorded during three Antarctic summers (1994- 1995, 1995-1996 and 1996-1997), are analyzed using a dense small-aperture (500 m) seismic array. The visual and spectral classification of the seismic events shows the existence of long-period and hybrid isolated seismic events, and of low-frequency, quasi-monochromatic and spasmodic continuous tremors, All spectra have the highest amplitudes in the frequency band between 1 and 4 Hz, while hybrids and spasmodic tremors have also significant amplitudes in the high-frequency band (4-10 Hz). The array analysis indicates that almost all the well-correlated low-frequency signals share similar array parameters (slowness and back azimuth) and have the same source area, close to the array site. The polarization analysis shows that phases at high-frequency are mostly composed of P waves, and those phases dominated by low frequencies can be interpreted as surface waves. No clear shear waves are evidenced. From the energy evaluation, we have found that the reduced displacement values for surface and body waves are confined in a narrow interval. Volcano-tectonic seismicity is located close to the array, at a depth shallower than 1 km. The wave-field properties of the seismovolcanic signals allow us to assume a unique source model, a shallow resonating fluid-filled crack system at a depth of some hundreds of meters. All of the seismic activity is interpreted as the response of a reasonably stable stationary geothermal process. The differences observed in the back azimuth between low and high frequencies are a near-field effect. A few episodes of the degassification process in an open conduit were observed and modeled with a simple organ pipe.
    Description: Published
    Description: 13905-13931
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Long Period Events ; Deception Island ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 35
    Publication Date: 2019-06-17
    Description: A high‐resolution paleomagnetic and rock magnetic study has been carried out on sediment cores collected in glaciomarine silty‐clay sequences from the continental shelf and slope of the southern Storfjorden trough‐mouth fan, on the northwestern Barents Sea continental margin. The Storfjorden sedimentary system was investigated during the SVAIS and EGLACOM cruises, when 10 gravity cores, with a variable length from 1.03 m to 6.41 m, were retrieved. Accelerator mass spectrometry (AMS) 14C analyses on 24 samples indicate that the cores span a time interval that includes the Holocene, the last deglaciation phase and in some cores the last glacial maximum. The sediments carry a well‐defined characteristic remanent magnetization and have a valuable potential to reconstruct the paleosecular variation (PSV) of the geomagnetic field, including relative paleointensity (RPI) variations. The paleomagnetic data allow reconstruction of past dynamics and amplitude of the geomagnetic field variations at high northern latitudes (75°–76° N). At the same time, the rock magnetic and paleomagnetic data allow a high‐resolution correlation of the sedimentary sequences and a refinement of their preliminary age models. The Holocene PSV and RPI records appear particularly sound, since they are consistent between cores and they can be correlated to the closest regional stacking curves (UK PSV, FENNOSTACK and FENNORPIS) and global geomagnetic model for the last 7 ka (CALS7k.2). The computed amplitude of secular variation is lower than that outlined by some geomagnetic field models, suggesting that it has been almost independent from latitude during the Holocene.
    Description: Published
    Description: Q11Z33
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Barents Sea ; Holocene ; Storfjorden ; geomagnetic paleosecular variation ; relative paleointensity ; 04. Solid Earth::04.05. Geomagnetism::04.05.01. Dynamo theory ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 36
    Publication Date: 2017-04-04
    Description: We report a laboratory and microstructural study of a suite of deformation experiments in which basalt from Mount Etna volcano is deformed and fractured at an effective confining pressure representative of conditions under a volcanic edifice (40 MPa). Particular attention was paid to the formation of a fracture and damage zone with which to stimulate coupled hydro-mechanical interactions that create the various types of seismicity recorded on volcanic edifices, and which usually precede eruption. Location of AE events through time shows the formation of a fault plane during which waveforms exhibit the typical high frequency characteristics of volcano-tectonic (VT) earthquakes. We found that these VT earthquakes were particularly pronounced when generated using dry samples, compared to samples saturated with a pore fluid (water). VT events generated during deformation of water saturated sample are characterised by a distinctive high frequency onset and a longer, low frequency coda exhibiting properties often seen in the field as hybrid events. We present evidence that hybrid events are, in fact, the common type of volcanic seismic event with either VT or low frequency (LF) events representing end members, and whose proportion depend on pore fluid being present in the rock type being deformed, as well as how close the rock is to failure. We find a notable trend of reducing instances of hybrid events leading up to the failure stage in our experiments, suggesting that during this stage, the pore fluid present in the rock moves sufficiently quickly to provide a resonance, seen as a LF coda. Our data supports recent modeling and field studies that postulate that hybrid events generated in volcanic areas are likely to be generated through the interaction of hydrothermal fluids moving through a combination of pre-existing microcrack networks and larger faults, such as those we observe in forensic (post-test) examination.
    Description: Published
    Description: 315-323
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: volcano-tectonics, acoustic emission, rock physics, seismology, hazard ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 37
    Publication Date: 2020-11-16
    Description: Active volcanoes characterized by open conduit conditions generate sonic and infrasonic signals, whose investigation provides useful information for both monitoring purposes and studying the dynamics of explosive processes. In this work, we discuss the automatic procedures implemented for a real-time application to the data acquired by a permanent network of five infrasound stations running at Mt. Etna volcano. The infrasound signals at Mt. Etna consist in amplitude transients, called infrasound events. The adopted procedure uses a multi-algorithm approach for event detection, counting, characterization and location. It is designed for an efficient and accurate processing of infrasound records provided by single-site and array stations. Moreover, the source mechanism of these events can be investigated off-line or in near real-time by using three different models: i) Strombolian bubble; ii) resonating conduit and iii) Helmholtz resonator. The infrasound waveforms allow us to choose the most suitable model, to get quantitative information about the source and to follow the time evolution of the source parameters.
    Description: Published
    Description: 1215–1231
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Description: open
    Keywords: infrasound ; monitoring system ; Mt. Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 38
    Publication Date: 2020-11-12
    Description: Fogo volcano is an active central volcano, with a lake filled caldera, in the central part of São Miguel Island, Azores, whose current activity is limited to hydrothermal manifestations such as active fumarolic fields, thermal and CO2 cold springs and soil diffuse degassing areas. It is affected by important active tectonic structures, with high seismic activity and practically continuous micro-seismicity. A recurrent feature from the seismicity observed in volcanic regions is the occurrence of clusters of similar earthquakes, whose origin can be attributed to the repeated action of a similar source mechanism at the same focal area. Doublets/multiplets were identified in this study within a catalogue of small magnitude (usually 〈 3) volcano tectonic events recorded in 2003–2004 by a selection of stations around Fogo volcano. All events have been cross-correlated and pairs whose waveforms exhibited a cross-correlation coefficient equal to or higher than 0.9 were analysed using the coda-wave interferometry technique. Subtle velocity variations found between events highlight a seasonal cycle of the velocity patterns, with lower velocity in winter time and higher velocity during summer months. Those results, together with quantitative differences between the same doublets at different stations, exhibit an excellent correlation with rainfall. A seasonal effect can also be broadly seen in the seismicity occurrence, and some of the swarms recorded over the two year period occur during the wettest season or close to episodes of abundant (above average) rainfall. Moreover, temporal and spatial analysis of several swarms highlighted the lack of any mainshock–aftershock sequence and organized migration of the hypocenters. This is suggestive of a very heterogeneous stress field. Vp/Vs is found to be lower than usually observed in volcanic areas, an occurrence likely related to the presence of steamy fluid associated with the geothermal system. Taken together, these observations suggest that pore pressurisation plays a major role in controlling a considerable part of the recorded seismicity. The geothermal fluids around Fogo massif have been identified as derived from meteoric water, which infiltrates through Fogo Lake and the volcano flanks and flows from south to north on the northern flank. All those elements seem to point to a role played by rainfall in triggering seismicity at São Miguel, possibly through pressure changes at depth in response to surface rain and/or an interaction with the geothermal system.
    Description: Published
    Description: 231-246
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: velocity changes ; rainfall ; volcano seismicity ; triggered seismicity ; Azores archipelago ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 39
    Publication Date: 2021-01-25
    Description: Continuous marine successions covering the Middle Miocene Climate Transition (MMCT; ∼15–13.7 Ma) are scarce and the lack of a high-resolution magnetobiostratigraphic framework hampers the construction of astronomically tuned age models for this time interval. The La Vedova High Cliff section, exposed along the coast of the Cònero Riviera near Ancona (Italy), is one of the few Mediterranean sections covering the critical time interval of the MMCT. Starting from an initial magnetobiostratigraphic age model, a robust astronomical tuning was constructed for the interval between 14.2 and 13.5 Ma, using geochemical element data and time series analysis. A shift in δ18O of bulk sediment towards heavier values occurs between ∼13.92 and 13.78 Ma and could be related to the Mi3b oxygen isotope event, which reflects the rapid expansion of the East Antarctic Ice Sheet in the middle Miocene. The onset of the CM6 carbon excursion is reflected in the bulk record by a rapid increase in δ13C at 13.86 Ma. Our results confirm the proposition that these events coincide with a 405-kyr minimum in eccentricity and a node in obliquity related to the ∼1.2 Myr cycle. From 13.8 Ma onwards, distinct quadruplet cycles containing sapropelitic sediments were deposited. This may suggest a causal connection between the main middle Miocene cooling step and the onset of sapropel formation in the Mediterranean.
    Description: Published
    Description: 249–261
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Middle Miocene ; Mediterranean ; astronomical tuning ; paleomagnetism ; biostratigraphy ; environmental changes ; orbital forcing ; sapropels ; 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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  • 40
    Publication Date: 2020-11-12
    Description: The number of tornillo events has recently increased at the Vulcano Island, Italy. While only 15 tornillos were recorded during 2004–2006, 584 events occurred in 2007–2008. They were located just below La Fossa Crater at depths ranging between 0.1 and 1 km b.s.l. During two intervals in 2007–2008 increases in the number of tornillos took place at the same time as temperature and geochemical anomalies were observed. The spectral content of the tornillos, generally characterized by one–two dominant spectral peaks near 6 and 10 Hz, varied over time, with changes also noted in the quality factors. The simplest source mechanism proposed for tornillos is the free eigenvibration of a fluid volume within a crack or a conduit. Based on this model, we propose a causal relationship between the temperature and geochemical anomalies and the increases in numbers of tornillos. As the amount of hydrothermal fluids increases during the anomalies, the upward flux of fluids grows. The consequent changes in the pressure, temperature and dynamics of the system of cracks and conduits result in the generation of tornillos. Based on the fluid-filled crack/conduit model, the shallow depths of the sources and the values of the quality factors, the fluid within the resonant crack/conduit was inferred to be an ash–gas or water droplet–gas mixture. Moreover, the observed variations in the wavefield can be caused by small changes in the location of the source, in the source mechanism, or in the medium in between the source and the seismic station. Finally, another peculiar feature of tornillos is the amplitude modulation that can be explained as a result of a beating phenomenon.
    Description: Published
    Description: 377-393
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Tornillos ; Vulcano Island ; Hydrothermal system ; Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 41
    Publication Date: 2017-04-04
    Description: The Piànico-Sèllere is a lacustrine succession from northern Italy that records a sequence of climatic transitions across two Pleistocene glacial stages. The intervening interglacial stage is represented by well-preserved varves with calcitic (summer) and clastic (winter) laminae. There is a tight coupling between climate-driven lithologic changes and magnetic susceptibility variations, and stable paleomagnetic components were retrieved from all investigated lithologies including the largely diamagnetic calcite varves. These components were used to delineate a sequence of magnetic polarity reversals that was interpreted as a record of excursions of the Earth’s magnetic field. Comparison of the magnetostratigraphic results with previously published data allows discussion of two possible models which have generated controversy regarding the age of the Piànico Formation. The data indicates that the Piànico Formation magnetostratigraphy correlates to geomagnetic field excursions across the Brunhes/Matuyama transition, and consequently the Piànico interglacial correlates to marine isotope stage 19. This correlation option is substantially consistent with K-Ar radiometric age estimates recently obtained from a tepha layer interbedded in the Piànico Formation. The alternative option, considering the Piànico interglacial correlative to marine isotope stage 11 within the Brunhes Chron as supported by tephrochronological dating reported in the literature, is not supported by the magnetostratigraphic results.
    Description: Published
    Description: 44-53
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Piànico Formation ; Pleistocene ; magnetostratigraphy ; polarity excursions ; Brunhes Chron ; Southern Alps ; 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::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 42
    Publication Date: 2012-02-03
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union
    Description: Seismic, deformation, and volcanic gas observations offer independent and complementary information on the activity state and dynamics of quiescent and eruptive volcanoes and thus all contribute to volcanic risk assessment. In spite of their wide use, there have been only a few efforts to systematically integrate and compare the results of these different monitoring techniques. Here we combine seismic (volcanic tremor and long‐period seismicity), deformation (GPS), and geochemical (volcanic gas plume CO2/SO2 ratios) measurements in an attempt to interpret trends in the recent (2007–2008) activity of Etna volcano. We show that each eruptive episode occurring at the Southeast Crater (SEC) was preceded by a cyclic phase of increase‐decrease of plume CO2/SO2 ratios and by inflation of the volcano’s summit captured by the GPS network. These observations are interpreted as reflecting the persistent supply of CO2‐rich gas bubbles (and eventually more primitive magmas) to a shallow (depth of 1–2.8 km asl) magma storage zone below the volcano’s central craters (CCs). Overpressuring of the resident magma stored in the upper CCs’ conduit triggers further magma ascent and finally eruption at SEC, a process which we capture as an abrupt increase in tremor amplitude, an upward (〉2800 m asl) and eastward migration of the source location of seismic tremor, and a rapid contraction of the volcano’s summit. Resumption of volcanic activity at SEC was also systematically anticipated by declining plume CO2/SO2 ratios, consistent with magma degassing being diverted from the central conduit area (toward SEC).
    Description: Published
    Description: Q09008
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: volcano monitoring ; Mt. Etna volcano ; geochemistry and geophysics ; volcanic tremor ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 43
    Publication Date: 2012-02-03
    Description: Influences of distant earthquakes on volcanic systems by dynamic stress transfer are well documented. We analyzed seismic signals and volcanic activity at Mount Etna during two periods, January 2006 and May 2008, that clearly showed variations coincident with distant earthquakes. In the first period, characterized by mild volcano activity, the effect of the dynamic stress transfer, caused by an earthquake in Greece (M = 6.8), was twofold: (1) banded tremor activity changed its features and almost disappeared; (2) a swarm of volcano‐tectonic (VT) earthquakes took place. The changes of the banded tremor were likely due to variations in rock permeability, caused by fluid flows driven by dynamic strain. The VT earthquake swarm probably developed as a secondary process, promoted by the dynamically triggered activation of magmatic fluids. The second period, May 2008, showed an intense explosive activity. During this interval, the dynamic stress transfer, associated with the arrival of the seismic waves of the Sichuan earthquake (M = 7.9), affected the character of the seismo‐volcanic signals and on the following day triggered an eruption. In particular, we observed changes in volcanic tremor and increases of both occurrence rate and energy of long period events. In this case, we suggest that dynamic stress transfer caused nucleation of new bubbles in volatile‐rich magma bodies with consequent buildup of pressure, highlighted by the increase of long period activity, followed by the occurrence of an eruption. We conclude that stresses from distant earthquakes are capable of modifying the state of the volcano.
    Description: Published
    Description: B12304
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Mt. Etna volcano ; dynamic stress transfer ; triggered eruption ; triggered seismicity ; volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 44
    Publication Date: 2017-04-04
    Description: Active volcanoes characterized by open conduit conditions generate sonic and infrasonic signals, whose investigation provides useful information for both monitoring purposes and studying the dynamics of explosive processes. In this work, we discuss the automatic procedures implemented for a real-time application to the data acquired by a permanent network of five infrasound stations running at Mt. Etna volcano. The infrasound signals at Mt. Etna consist in amplitude transients, called infrasound events. The adopted procedure uses a multi-algorithm approach for event detection, counting, characterization and location. It is designed for an efficient and accurate processing of infrasound records provided by single-site and array stations. Moreover, the source mechanism of these events can be investigated off-line or in near real-time by using three different models: (1) Strombolian bubble; (2) resonating conduit and (3) Helmholtz resonator. The infrasound waveforms allow us to choose the most suitable model, to get quantitative information about the source and to follow the time evolution of the source parameters.
    Description: Published
    Description: 1215–1231
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Infrasound ; monitoring system ; Mt. Etna volcano ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 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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  • 45
    Publication Date: 2017-04-04
    Description: We investigated the banded tremor activity occurring at Mt. Etna volcano between August-October 2008 during the 2008-2009 eruption. The banded tremor occurred in episodes lasting 25-30 minutes with intervals in between the episodes of about 25 minutes. Seismic signal analyses showed that the banded tremor was characterised by spectral contents, wavefields and source locations that differed from the “ordinary” volcanic tremor. The infrasound recordings exhibited an intermittent infrasonic tremor alternating with the banded tremor episodes. Finally, nonlinear analyses suggested that banded tremor system can be considered chaotic, implying: i) sensitive dependence on initial conditions, suggesting not only that a banded tremor system requires particular conditions to generate, but also that slight variations of these conditions are able to greatly change the features of the banded tremor or even to stop it; ii) long-term unpredictability, that is, the impossibility to forecast the long-term evolution of the banded tremor. On the basis of all these results and analogies with geyser models, we suggest a model of banded tremor that invokes alternating recharge-discharge phases. Banded tremor is due to “perturbations” in shallow aquifers, such as fluid movement and bubble growth or collapse due to hydrothermal boiling, triggered by the heat and hot fluid transfer from the underlying magma bodies. This heat-fluid transfer also causes an increasing pressure in the aquifer leading to fluid-discharge. During this process the seismic radiation decreases and, if the fluid-discharge is well coupled with the atmosphere, acoustic signals are generated.
    Description: Published
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Banded tremor ; Mt. Etna volcano ; volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 46
    Publication Date: 2017-04-04
    Description: Stromboli is considered one of the most active volcanoes in the world, and its persistent but moderate explosive activity is only interrupted by occasional episodes of more vigorous activity accompanied by lava flows. A new effusive eruption began in late February, 2007 and was characterised by intense seismic activity throughout the whole period. The accurate seismic signals analysis showed the presence of families of events with similar waveform signatures (i.e. multiplets) located beneath the crater region. Since traditional location techniques do not allow obtaining reliable hypocentres, our analysis focused on high precision locations of the seismicity, in order to better define the source geometry of the events. Hypocentres, therefore, have been relocated considering two steps: the first, based on a robust probabilistic approach, is used to find the absolute position of the clusters; the second exploits a master-event concept for the relative location of the events. Finally, the shape of the clusters and the temporal migration of the foci were correlated with the eruptive phases. The results show that the occurrence of a cluster of events is related to the opening and closure of a vent opened in the Sciara del Fuoco slope and, in particular, to the intrusion of a dike injected by central conduit in a radial direction, whereas another cluster lies in a narrow vertical volume positioned under the crater area. The geometry of the clusters suggests a source region depicting the shallower feeding system. Overall, the results highlight that the high precision locations method is an efficient and quick tool to obtain a better understanding of the magmatic processes occurring during an ongoing eruption.
    Description: Published
    Description: 405-415
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: eruption ; high precision location ; seismic swarms ; magma dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 47
    Publication Date: 2017-04-04
    Description: An integrated bio-, magneto- and cyclostratigraphic study of the Ypresian/Lutetian (Early/Middle Eocene) transition along the Otsakar section resulted in the identification of the C22n/C21r chron boundary and of the calcareous nannofossil CP12a/b zonal boundary; the latter is the main correlation criterion of the Lutetian Global Stratotype Section and Point (GSSP) recently defined at Gorrondatxe (Basque Country). By counting precession-related mudstone–marl couplets of 21 ka, the time lapse between both events was calculated to be 819 ka. This suggests that the age of the CP12a/b boundary, and hence that of the Early/Middle Eocene boundary, is 47.76 Ma, 250 ka younger than previously thought. This age agrees with, and is supported by, estimates from Gorrondatxe based on the time lapse between the Lutetian GSSP and the C21r/C21n boundary. The duration of Chron C21r is estimated at 1.326 Ma. Given that the base of the Eocene is dated at 55.8 Ma, the duration of the Early Eocene is 8 Ma, 0.8 Ma longer than in current time scales. The Otsakar results further show that the bases of planktonic foraminiferal zones E8 and P10 are younger than the CP12a/b boundary. The first occurrence of Turborotalia frontosa, being approximately 550 ka older that the CP12a/b boundary, is the planktonic foraminiferal event that lies closest to the Early/Middle Eocene boundary. The larger foraminiferal SBZ12/13 boundary is located close to the CP12a/b boundary and correlates with Chron C21r, not with the C22n/C21r boundary.
    Description: In press
    Description: 1-19
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Eocene ; Ypresian–Lutetian boundary ; biostratigraphy ; magnetostratigraphy ; cyclostratigraphy ; 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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  • 48
    Publication Date: 2017-04-04
    Description: An integrated high-resolution magnetobiocyclostratigraphy including radioisotopic dating and astronomical tuning is presented for the interval between 15.29 and 14.17 Ma in the marine La Vedova section in northern Italy. The natural remanent magnetization is carried by the iron sulphide greigite and the resultant magnetostratigraphy can be correlated straightforwardly to the interval ranging from C5Bn.2n to C5ADn in the Astronomically Tuned Neogene Time Scale (ATNTS2004). Spectral analysis on high-resolution magnetic susceptibility and geochemical proxy records in the depth domain and, using our magnetobiostratigraphic age model, in the time domain demonstrate that the various scales of cyclicity in the section are related to astronomical climate forcing. Starting from our initial age model, larger-scale cycles were first tuned to eccentricity. This first-order tuning was followed by tuning the basic cycle to precession and boreal summer insolation using inferred phase relations between maxima in Ca/Al, redox-sensitive elements and Ba, and minima in magnetic susceptibility, and maxima in precession and minima in obliquity and boreal summer insolation. Our astronomical ages for reversal boundaries are supported by analysis of sea floor spreading rates and should replace the existing ages in the ATNTS2004 lacking direct astronomical control. Two major steps in the geochemical proxy records, astronomically dated at 15.074 and 14.489 Ma, coincide with abrupt changes in sedimentation rate, and are the result of the combined effect of the ∼400-kyr eccentricity cycle superimposed upon a longer-term climatic or tectonic induced trend.
    Description: Published
    Description: 254–269
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Middle Miocene ; Langhian ; Mediterranean ; astronomical tuning ; palaeomagnetism ; biostratigraphy ; environmental changes ; orbital forcing ; 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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  • 49
    Publication Date: 2019-03-05
    Description: A three-dimensional S wave attenuation tomography of Mt. Vesuvius has been obtained with multiple measurements of coda-normalized S-wave spectra of local small magnitude earthquakes.We used 6609 waveforms, relative to 826 volcano-tectonic earthquakes, located close to the crater axis in a depth range between 1 and 4 km (below the sea level), recorded at seven 3-component digital seismic stations. We adopted a two-point ray-tracing; rays were traced in an high resolution 3-D velocity model. The spatial resolution achieved in the attenuation tomography is comparable with that of the velocity tomography (we resolve 300m side cubic cells). We statistically tested that the results are almost independent from the radiation pattern. We also applied an improvement of the ordinary spectral-slope method to both P- and S-waves, assuming that the differences between the theoretical and the experimental high frequency spectral-slope are only due to the attenuation effects. Consequently we could check the codanormalization method also comparing the S attenuation image with the P attenuation image. The images were obtained inverting the spectral data with a multiple resolution approach. Results have shown the general coincidence of low attenuation with high velocity zones. The joint interpretation of velocity and attenuation images allows us to interpret the low attenuation zone intruding toward the surface until a depth of 500m below the sea level as related to the residual part of solidified magma from the last eruption. In the depth range between −700 and −2300 images are consistent with the presence of multiple acquifer layers. No evidence of magma patches greater than the minimum cell dimension (300m) has been found. A shallow P wave attenuation anomaly (beneath the southern flank of the volcano) is consitent with the presence of gas saturated rocks. The zone characterized by the maximum seismic energy release cohincides with a high attenuation and low velocity volume, interpreted as a cracked medium.
    Description: Published
    Description: 17–32
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Attenuation tomography ; Mt. Vesuvius ; Coda normalization method ; Spectral slope ; Multi resolution inversion ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 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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  • 50
    Publication Date: 2020-02-24
    Description: We investigated the relationship between volcano-seismic events, recorded at La Fossa crater of Vulcano (Aeolian Islands, Italy) during 2004-2006, and the dynamics of the hydrothermal system. During the period of study, three episodes of increasing numbers of volcano-seismic events took place at the same time as geothermal and geochemical anomalies were observed. These geothermal and geochemical anomalies have been interpreted as resulting from an increasing deep magmatic component of the hydrothermal fluids. Three classes of seismic events (long period, high frequency and monochromatic events), characterised by different spectral content and various similarity of the waveforms, have been recognised. These events, clustered mainly below La Fossa crater area at depths of 0.5–1.1 km b.s.l., were space-distributed according to the classes. Based on their features, we can infer that such events at Vulcano are related to two different source mechanisms: (1) fracturing processes of rocks and (2) resonance of cracks (or conduits) filled with hydrothermal fluid. In the light of these source mechanisms, the increase in the number of events, at the same time as geochemical and geothermal anomalies were observed, was interpreted as the result of an increasing magmatic component of the hydrothermal fluids, implying an increase of their flux. Indeed, such variation caused an increase of both the pore pressure within the rocks of the volcanic system and the amount of ascending fluids. Increased pore pressures gave rise to fracturing processes, while the increased fluid flux favoured resonance and vibration processes in cracks and conduits. Finally, a gradual temporal variation of the waveform of the hybrid events (one of the subclasses of long period events) was observed, likely caused by heating and drying of the hydrothermal system.
    Description: Published
    Description: 803-816
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Vulcano Island ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 51
    Publication Date: 2017-04-04
    Description: A 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 lowmagnitude, tectonic earthquakes that 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 were 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: Published
    Description: 247-256
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: rise time ; directivity ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 52
    Publication Date: 2017-04-04
    Description: The Danian–Selandian (D–S) boundary has been identified for the first time in the Black Sea coast at Bjala (Bulgaria) based on a new integrated bio-, magneto- and cyclostratigraphic study. Several correlation criteria as established for the basal Selandian GSSP from Zumaia (Basque Basin) are evaluated. Noteworthy, is the almost complete lack of calcareous nannoplankton species Braarudosphaera bigelowi in the Bulgarian sections, a sharp decrease of which was indicated as suitable criteria for defining the D–S boundary as it occurred both at Zumaia and in the classical locations of the North Sea basin. Conversely, the second evolutionary radiation of the calcareous nannofossil genus Fasciculithus together with the occurrence of Fasciculithus tympaniformis that define the NP4/NP5 zonal boundary seem to be reliable criteria to approximate the D–S boundary. In detail, however, the best approach is to integrate biostratigraphic data within a magnetostratigraphic and/or cyclostratigraphic framework. Refinements on the placement of chron C27n at Zumaia and robust bed-by-bed correlation between several Basque sections and Bjala indicates that the D–S boundary is located 30 precession cycles (~630 ky) above C27n. In addition to the precession-related marl–limestone couplets and 100-ky eccentricity bundles recognized in the studied sections, expression of the stable 405-ky long eccentricity allows direct tuning to the astronomical solutions. A correlation of the land-based sections with previously tuned data from ODP Site1262 from the Southern Atlantic is challenged. Our choice is consistent with original tuning at Zumaia but shifts one 100-ky cycle older previous tuning from Site 1262 along the interval above C27n. Under the preferred tuning scheme the D–S boundary can be given an age of 61.641± 0.040 Ma on the La04 orbital solution.
    Description: Published
    Description: 511-533
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Paleocene ; Magnetostratigraphy ; Orbital tuning ; Calcareous nannofossils ; Selandian GSSP ; 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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  • 53
    Publication Date: 2017-04-04
    Description: The Fortuna Basin is an example of a marginal Mediterranean basin with evaporitic sedimentation during the Late Tortonian and Messinian. This basin shows an early restriction event before the main Messinian Salinity Crisis (MSC) that allows the Tortonian Salinity Crisis (TSC) to be proposed as a tectonic uplift event isolating the eastern Betic basins. Four evaporitic events are present in the central part of the Fortuna Basin, from bottom to top: Los Baños Marls Formation (composed by Fenazar Conglomerate Bed, Lower Gypsum Member [Mb] and Sanel Mb), Tale Gypsum Formation (Fm), Chicamo Diatomites and Gypsum Cycles Fm, and Rambla Salada Gypsum Fm. The present work documents the first biostratigraphic dating based on calcareous nannoplankton of these events. The lowest occurrence (LO) of Amaurolithus primus is registered at the upper part of the Sanel Mb, below the Tale Gypsum Fm. The LOs of Amaurolithus delicatus and Reticulofenestra rotaria, which mark the base of the Messinian, occur in the lower part of the Chicamo Cycles Fm, above the Tale Gypsum Fm, the Triquetrorhabdulus rugosus-Nicklithus amplificus integrate form and the LO of Nicklithus cf. amplificus in the upper part of the Chicamo Cycles Fm. Taking into account these results, a new calibration of the available magnetostratigraphic data is presented: the Chicamo Cycles Fm were formed during the reverse chron C3Ar and the Tortonian-Messinian boundary should be found within the Tale Gypsum Fm or near the top of the Sanel Mb. The onset of the TSC, the first restriction phase of the Fortuna Basin, is represented by the Fenazar Conglomerate Bed, bottom of the Los Baños Fm, and not by the Tale Gypsum Fm, as previously considered.
    Description: Published
    Description: 201-217
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Betic Cordillera ; Tortonian Salinity Crisis ; Calcareous nannoplankton ; Messinian ; Fortuna Basin ; 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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  • 54
    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 braidplam 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 Gunz and Alterer 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: Regione Lombardia, IREALP
    Description: Published
    Description: 832–846
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Paleomagnetism ; Climate Change ; Early Pleistocene ; Italy ; Stratigraphy ; Petrography ; Palynology ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models ; 04. Solid Earth::04.04. Geology::04.04.02. Geochronology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 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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  • 55
    Publication Date: 2017-04-04
    Description: A critical assessment of the available magnetostratigraphic and/or radiometric age constraints on key sites bearing hominin remains and/or lithic industries from southern Europe (Italy, France, Spain) leads us to propose that the main window of early hominin presence in southern Europe is broadly comprised between the Jaramillo subchron and the Brunhes–Matuyama boundary (i.e., subchron C1r.1r, 0.99–0.78 Ma). Within the dating uncertainties, this ~200 ky time window broadly coincides with the late Early Pleistocene global climate transition that contains marine isotope stage (MIS) 22 (~0.87Ma), the first prominent cold stage of the Pleistocene. We suggest that aridification in North Africa and Eastern Europe, particularly harsh during MIS22 times, triggered migration pulses of large herbivores, particularly elephants, from these regions into southern European refugia, and that hominins migrated with them. Finally, we speculate on common pathways of late Early Pleistocene dispersal of elephants and hominins from their home in savannah Africa to southern Europe, elephant and hominin buen retiro. In particular, we stress the importance of the Po Valley of northern Italy that became largely and permanently exposed only since MIS22, thus allowing possibly for the first time in the Pleistocene viable new migration routes for large mammals and hominins across northern Italy to southern France and Spain in the west.
    Description: Published
    Description: 79-93
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Pleistocene ; Magnetostratigraphy ; Hominins ; Migration ; Europe ; Galerian ; Jaramillo ; Brunhes-Matuyama ; 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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  • 56
    Publication Date: 2017-04-04
    Description: Aim of this paper is to identify variations in Very-Long-Period (VLP) source associated with eruptive style changes at Stromboli volcano (Italy) and to retrieve information about the shallow plumbing system that sustains the eruptive activity. We have considered a dataset of 74493 VLP events recorded during the period from January through August 2007, when an effusive eruption occurred (February 27–April 2).We performed a polarization analysis of the entire dataset and divided the considered period into four sub-periods on the basis of polarization characteristics. We then located the events and selected a subset of these events by applying a location quality threshold. The high quality locations demonstrate that during the effusive eruption the VLP sources first moved downward and then moved southwestward. To retrieve information about the geometry of the structures where the source processes take place, we further consider a subset of events and estimate their source mechanisms by using a moment tensor source function (MTSF) inversion technique. Inversion of the waveforms of the VLP events that occurred on February 27 allows us to obtain information about the dynamics of different source centroids distributed along different portions of the shallow magmatic conduits. The structure defined by the locations and source mechanisms shows a greater complexity compared with previous studies and their time variations give an insight into the kinematics of the eruption.
    Description: Published
    Description: 162–171
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: stromboli ; very-long-period events ; seismic source mechanism ; volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 57
    Publication Date: 2017-04-04
    Description: We analyze the distribution of volcanic earthquake recurrence intervals in the Vesuvio, Campi Flegrei, and Hawaii regions and compare it with tectonic recurrence rates in California. We find that the distribution behavior is similar for volcanic and tectonic seismic events. In both cases, the recurrence interval distributions collapse onto the same master curve if time is rescaled by the average occurrence rate. This implies that both phenomena have the same temporal organization, and it is possible to adopt for volcanic areas that the same occurrence models used for tectonic regions.
    Description: Published
    Description: B10309
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic earthquake ; recurrence intervals ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 58
    Publication Date: 2017-04-04
    Description: We report on the paleomagnetism of ten sites in the products of the most recent silicic eruptive cycle of Pantelleria, Strait of Sicily. Previously radiometrically dated at 5–10 ka, our comparison with proxies for geomagnetic field directions allows us to narrow considerably the time window during which these eruptions occurred. The strongly peralkaline composition causes the magmas to have low viscosities, locally resulting in strong agglutination of proximal fall deposits. This allows successful extraction of paleomagnetic directions from the explosive phases of eruptions. One of our sites was located in the Serra della Fastuca fall deposit, produced by the first explosive event of the eruptive cycle. The other nine sites were located in the most recent explosive (pumice fall and agglutinate from Cuddia del Gallo and Cuddia Randazzo) and effusive (Khaggiar lava) products. The (very similar) paleomagnetic directions gathered from eight internally consistent sites were compared to reference geomagnetic field directions of the last 5–10 ka. Directions from Cuddia del Gallo agglutinate and Khaggiar flows translate into 5.9- to 6.2-ka ages, whereas the Fastuca pumices yield a slightly older age of 6.2–6.8 ka. Hence, the most recent silicic eruptive cycle lasted at most a millennium and as little as a few centuries around 6.0 ka. Paleomagnetically inferred ages are in good agreement with published (and calibrated by us) 14C dates from paleosols/charcoals sampled below the studied volcanic units, whereas K/Ar data are more scattered and yield ∼30% older ages. Our data show that the time elapsed since the most recent silicic eruptions at Pantelleria is comparable to the quiescence period separating the two latest volcanic cycles.
    Description: Published
    Description: 847-858
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: pantelleria ; peralkaline deposits ; paleomagnetic dating ; chronology of eruptions ; cluster of the eruptions ; volcanic hazard ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 59
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    Empirical economics 24 (1999), S. 23-44 
    ISSN: 1435-8921
    Keywords: Key words: Cointegration ; convergence ; growth ; Kalman filter ; JEL classifications: C22 ; O47 ; O57
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract. Augmented Dickey Fuller (ADF) and Kalman filter convergence tests are applied to annual GDPs per head to 16 industrialised countries from 1890 to 1989. Results favour convergence towards the US with a structural break following the Second World War. Estimates suggest that steady-states were higher after the war and that speeds of convergence are different across countries. The Kalman filter method dismissed the no convergence hypothesis more often than its ADF counterpart. This could explain the apparent contradiction in earlier empirical work on similar data sets (cross-section methods tended to favour convergence while time series methods were unable to dismiss the no convergence hypothesis.)
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  • 60
    ISSN: 1572-977X
    Keywords: Avicennia alba ; growth ; internodal sequences ; mangrove age determination ; Rhizophora apiculata ; Sonneratia caseolaris ; Thailand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The occurrence of periodic changes in the length of the internodes of the seedlings of SE Asian mangrove species (Rhizophora apiculata, Avicennia alba, and Sonneratia caseolaris) growing in the Pak Phanang estuary (Nakhon Si Thammarat, SE Thailand) was confirmed. The annual nature of these periodic changes was verified through comparisons with the observed average number of internodes produced by plants tagged for one year. The cycles in the sequence of internodal length of the seedlings had an average (± SE) period of 16.0 ± 0.78 internodes for Avicennia alba, 25.0 ± 1.2 internodes for Sonneratia caseolaris, and 8.29 ± 0.40 internodes for Rhizophora apiculata. These values are remarkably close to, and not significantly different (t‐test, P 〉 0.05) from the average (± SE) annual number of internodes of 17.6 ± 0.8 for Avicennia alba, 28.8 ± 2.1 for Sonneratia caseolaris, and 8.03 ± 0.36 for Rhizophora apiculata produced in a year by tagged plants. In addition, the average (± SE) growth of the tagged plants was 0.39 ± 0.018 cm day-1 for Avicennia alba, 0.24 ± 0.015 cm day-1 for Sonneratia caseolaris, and 0.091 ± 0.0036 cm day-1 for Rhizophora apiculata. These estimates were very close to those (0.45 ± 0.06 cm day-1 for Avicennia alba, 0.32 ± 0.01 cm day-1 for Sonneratia caseolaris, and 0.13 ± 0.005 cm day-1 for Rhizophora apiculata) derived as the product of the mean number of internodes produced per day, calculated from the inferred number of internodes produced per year, and the mean length of the internodes of the plants. These findings indicate that the use of regular, annual changes in the length of the internodes of mangrove seedlings can be used reliably to determine their age and to estimate their growth rate.
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  • 61
    ISSN: 1573-143X
    Keywords: bighead carp (Aristichthys nobilis) ; growth ; Laguna Lake ; salinity tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bighead carp (Aristichthys nobilis Oshima) fry of various ages (11, 18, and 35 days post-hatch) were exposed to the low salinities encountered during the annual intrusion of seawater in Laguna Lake, Philippines. Practical indices of salinity tolerance assessed the effect of a 96 h direct exposure to low salinities (0–16‰). Mean (MST) and median survival times (MST50) of fry decreased as salinity of rearing medium increased. Younger fry were less able to tolerate exposure to these salinities than their older cohorts. Median lethal salinity after 96 h (MLS) revealed higher tolerance among 35–day old fry (7.6‰) than 11 (2.3‰) and 18–day old fry (6.0‰), demonstrating that survival in saline water depends on their age at initial exposure to low salinities. Mean body weight of 18–day old fry reared in 0 and 2‰ for 3 and 4 weeks was higher than for those reared in 4 and 6‰ for the same period. Growth over these periods was inversely related with the range of salinities tested. These results demonstrate that, despite their known stenohalinity, bighead carp fry possess some degree of osmoregulatory capability, allowing them to survive and grow in lakes subjected periodically to saltwater inflow.
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  • 62
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    Aquaculture international 7 (1999), S. 287-293 
    ISSN: 1573-143X
    Keywords: bone mineralization ; calcium requirement ; feed efficiency ; growth ; semi-purified diet ; tiger puffer (Takifugu rubripes)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Juvenile tiger puffer (Takifugu rubripes) were fed semi-purified diets with graded levels (0–0.40%) of calcium (Ca) supplements for 8 weeks at a temperature of 23.0–25.5 °C. At the end of the feeding experiment, average final body weight increased with increasing dietary Ca levels. A diet without Ca supplement resulted in poor average final body weight and 0.05% dietary Ca supplement could not significantly improve the growth. However, supplemental Ca levels of 0.10–0.40% significantly increased growth. Dietary Ca supplements of 0.10% or more also improved the feed efficiency in tiger puffer. Ca and phosphorus contents of the bone were independent of dietary Ca supplements. However, 0.40% Ca in the diet decreased the zinc and manganese contents of bone. Results indicated that supplemental Ca levels of 0.10–0.20% in a semi-purified diet were required to maintain normal growth, feed utilization and bone mineralization of tiger puffer.
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  • 63
    ISSN: 1573-4919
    Keywords: NADH oxidase ; protein disulfide-thiol interchange ; dipyridyl-dithio substrates ; plasma membrane ; auxin ; 2,4-dichlorophenoxyacetic acid ; growth ; plant (Glycine max)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Dipyridyl-dithio substrates were cleaved by isolated vesicles of plasma membranes prepared from etiolated hypocotyls of soybean. The cleavage was stimulated by auxins at physiological concentrations. The substrates utilized were principally 2,2′-dithiodippyrine (DTP) and 6,6′-dithiodinicotinic acid (DTNA). The DTP generated 2 moles of 2-pyridinethione whereas the 6,6′-dithiodinicotinic acid generated 2 moles of 6-nicotinylthionine. Both products absorbed at 340 nm. The auxin herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D) stimulated the activity approximately 2-fold to a maximum at about 10 μM. Concentrations of 2,4-D greater than 100 μM inhibited the activity. Indole-3-acetic acid stimulated the activity as well. The growth-inactive auxin, 2,3-dichlorophenoxyacetic acid (2,3-D), was without effect. DTNA cleavage correlated with oxidation of NADH and reduction of protein disulfide bonds reported earlier in terms of location at the external plasma membrane surface, absolute specific activity, pH dependence and auxin specificity. The dipyridyl-dithio substrates provide, for the first time, a direct measure of the disulfide-thiol interchange activity of the protein previously measured only indirectly as an auxin-dependent ability of isolated plasma membrane vesicles to restore activity to scrambled and inactive RNase.
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  • 64
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    Journal of chemical ecology 25 (1999), S. 1455-1479 
    ISSN: 1573-1561
    Keywords: Turnera ulmifolia ; Euptoieta hegesia ; cyanogenesis ; Anolis sagrei ; tritrophic interactions ; host range ; sequestration ; growth ; development ; oviposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We examine the effects of the cyanogenesis polymorphism in Turnera ulmifolia on larvae, pupae, and adults of Euptoieta hegesia, the most damaging herbivore of T. ulmifolia in terms of tissue loss per unit time. We provide evidence that female E. hegesia do not show preference for host plants on the basis of their cyanogenesis level but do prefer T. ulmifolia over equally cyanogenic, closely related secondary host-plant species (Passiflora sp.). Similarly, cyanogenesis in T. ulmifolia has little effect on the food preference, growth, or development of the larvae. The potential host range of E. hegesia is limited, even within the genus Turnera, but this does not appear to be due to host-plant cyanogenesis. Pupae suffer very high mortality levels in the wild that are not associated with host-plant cyanogenesis, although our studies indicate that larvae are capable of sequestering cyanogenic glycosides from their host plants and possibly of synthesizing these or similar compounds. We provide evidence that the presence of sequestered cyanogenic compounds in the larvae protects them from terrestrial-based predators such as Anolis lizards
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  • 65
    ISSN: 1573-3017
    Keywords: Tubifex tubifex ; sediment bioassay ; hormesis ; growth ; reproduction ; egestion rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Toxicity assessment based on sediment chronic bioassays with the aquatic worm Tubifex tubifex was performed at ten contaminated sites in the industrial area of Bilbao (Northern Spain). One control and three reference sites were also included. Tubifex bioassay measures both survival and reproduction impairment. These endpoints have been contrasted and discussed in relation to somatic growth and both individual and total biomass of cocoons. Survival was only affected at one site which was heavily contaminated by organic compounds, mainly PAHs. A group of four severely ecotoxic sediments was characterised by a drastic reduction in number and size of cocoons, and adult somatic growth. In other group of sediments, some significant increases were found for these variables. It is suggested that these increases represent an effect of hormesis. An index of reproductive effort was used to integrate the relationship between somatic growth and reproduction. Values of reproductive effort at the test sediments were lower than those at the control sediment, suggesting a conservative strategy of oligochaete worms which consisted in an investment into somatic line (growth) at the expenses of offspring. Rates of food consumption which were estimated from egestion rates, were low at the contaminated sites. This fact could be related to the low production levels found at these sites and may reflect avoidance feeding behaviour of the oligochaete worms within the sediments. At some reference sites, high production could have resulted from high nutritional quality of sediments, or to an hormetic effect due to low concentration of some chemicals. Results are discussed in relation to toxicity data from sediment three-brood bioassay with Daphnia magna Straus performed separately on the same sediments.
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  • 66
    ISSN: 1573-5176
    Keywords: agar ; Gracilaria tenuistipitata ; growth ; salinity ; seawater pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acclimation responses of the red alga Gracilaria tenuistipitata var. liui collected on the northwest coast of Philippines were determined in laboratory setups and outdoor cultivation tanks in Haifa, Israel. Growth under laboratory conditions was influenced by all three variables studied, namely, temperature (20 or 30 °C), salinity (20, 30 or39‰) and seawater pH (6.5, 7.0, 8.0 or ≥ 9.0). In 250 mL flasks lacking pH control growth was influenced by temperature only at 20 ‰, whereas at 39 ‰, growth rates were similar at 20 or 30 °C. In 500 mL cylinders in which pH was controlled, growth rates were significantly different at a pH of 6.5 and 7.0 for all salinities, with maximal rates occurring in 39 ‰. At pH 8.0, and above, growth rates between salinities were similar and reduced to approximately 50% at a pH of 9.0 compared to rates at a pH of 6.5. Photosynthesis responses generally resembled growth responses both, in 250 mL and 500 mL cultures. In 40-L outdoor tanks, weekly growth and agar yields were apparently enhanced by increasing light intensities (up to full sunlight) and nutrient concentrations (up to 0.2 mM PO3 2- and 2.0 mM NH4 +), and rates averaged four times higher than rates determined in the smaller flask cultures. This study shows broad salinity tolerance of G. tenuistipitata var. liui and its ability to sustain growth rates that are among the highest measured for Gracilaria spp. in outdoor cultures.
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  • 67
    ISSN: 1573-5125
    Keywords: eutrophication ; feeding ; growth ; Mytilus edulis ; validation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract EMMY is an ecophysiological model of the growth and reproduction of a single mussel (Mytilus edulis L.). It contains feedback loops in the uptake and metabolism of food and in the partitioning of carbon and nitrogen to the internal state variables somatic tissue, storage, organic shell matrix and gametes. In this paper EMMY is used to simulate individual mussel growth in a series of mesocosm experiments with different inorganic nutrient loads (N and P). The experiments explore the impact of eutrophication reduction scenarios on mussel growth under defined and controlled conditions. In earlier studies EMMY was calibrated using expert knowledge on growth and reproduction during a period of 5 years. The resulting calibrated model was validated for system inputs and observations of three ecosystems with significantly different food and silt concentrations. EMMY reproduced the mussel growth sufficiently accurate in ecosystems with moderate or high food concentrations. In this study EMMY was adapted in order to cope with low food concentrations, then recalibrated (using the original calibration data and procedure) and applied without further calibration to 3 replicated mesocosm experiments. The EMMY simulations in this study show the ecophysiological response of mussels to different food (phytoplankton and detritus) concentrations. It is concluded that the mussels can adapt to significantly reduced food concentrations, due to inorganic nutrient load reduction, and still maintain growth.
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  • 68
    ISSN: 1573-0778
    Keywords: batch culture ; conditioned medium ; growth ; hybridoma ; inoculum ; protein productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Apart from gas concentrations, temperature, and pH, generally only the initial conditions can be manipulated in batch culture. Inoculum size and initial conditioned medium concentration represent two important considerations for optimal batch production. Two hybridoma cell lines were used to assess the impact of these initial conditions on population growth and monoclonal antibody productivity in suspension batch culture. Varying initial cell concentration over the range of 1.0 × 105 cells mL-1 to 3.0 × 105 cells mL-1 did not affect maximum product titre or maximum volumetric cell-hours attained. Initial percent of conditioned medium up to 40 percent strongly impacted on population growth and productivity, with initial levels of 30 to 40% conditioned medium reducing or eliminating lag phase and increasing average viable cell density. However, specific productivity and product titre declined with increasing initial percent conditioned medium, even on a per volume of fresh medium basis. Glutamine and glucose depletion or ammonia toxicity could cause depressed product titres when conditioned medium is used. Glutamine and glucose levels can easily be replenished in conditioned medium at minimal cost, and ammonia can be removed. Specific productivity was higher during cyclic batch operating mode than during batch operating mode. This may be because cyclic batch operating mode results in an incidental volume of conditioned medium at the beginning of each cycle. A two stage, cyclic-batch/batch operating mode can be employed to fully utilize medium and maximize product titre.
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  • 69
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    Journal of applied phycology 11 (1999), S. 293-299 
    ISSN: 1573-5176
    Keywords: organismic determinants ; Gracilaria gracilis ; Rhodophyta ; regeneration ; growth ; mariculture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of Gracilaria gracilis (Stackhouse) Steentoft, Irvine et Farnham was examined by studying the effect of organismic determinants such as thallus length, position along the thallus and branching. Knowledge of these factors is essential in order to increase production from suspended seaweed rafts seeded with vegetative G. gracilis fragments. Seeding netlons with seaweed material freshly collected from subtidal populations provided up to 30% higher relative growth rates than seaweed maintained on the netlons for successive months. Initial seedstock length greatly affected growth rates and yields such that 30-cm thalli fragments resulted in growth rates 14% higher than for 10-cm fragments. This difference is suggested to be due to the higher contribution to overall biomass by growth of lateral branches. Comparisons of the growth of apical and basal fragments suggest that growth takes place over the entire length of the thallus, but that the apex contributes more to overall elongation than does the proximal part. The removal of apical meristems resulted in an enhanced branching frequency with production of four times as many branches as intact fragments. Evidence is also provided for extensive morphological differentiation following long periods of rapid growth. These thalli have very high frequency of branching, are hollow due to the disintegration of medullary cells and are considered to be completely senescent. These factors have implications for the successful cultivation of G. gracilis on commercial mariculture systems.
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  • 70
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    Journal of applied phycology 11 (1999), S. 551-558 
    ISSN: 1573-5176
    Keywords: Nodularia ; growth ; hepatotoxin production ; nodularin ; salinity ; irradiance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this work was to determine the influence of total dissolved solids/salinity (TDS mgL-1) on growth and biomass specific rates of nodularin (hepatotoxin) production by Nodularia spumigena 001E isolated from Lake Alexandrina, South Australia. Maximum biomass yield (dry matter, chlorophyll a and particulate organic carbon/POC) at 80 μmol photon m-2 s-1 was recorded at 3300 mg TDS L-1 and decreased at salinities above or below this value (p 〈 0.05). The maximum biomass yield (dry matter and chlorophyll a) at 30 μmol m-2 s-1 occurred at a higher salinity of 9900 mg TDS L-1. Cultures grown at 80 μmol m-2 s-1, at a TDS〉 6600 mg L-1, had significantly (p 〈 0.05) lower nodularin content (ml-1 medium) than cultures grown at the same salinities at 30 μmolm-2 s-1. The maximum total toxin concentration (mL-1 medium) occurred at 9900 and 3300 mg TDS L-1 at 30 μmol m-2 s-1and 80 μmol m-2 s-1 respectively. Toxin per unit biomass, expressed as dry matter, chlorophyll a and POC was similar for cultures grown at 30 μmol m-2 s-1 or 80 μmol m-2s-1 at salinities 〈 6600 mg TDS L-1. At salinities 〉 9900 mg TDS L-1 the toxin content per unit biomass decreased at both irradiances, however, cultures grown at 30 μmol m-2s-1 had a higher toxin content than those grown at 80 μmol m-2 s-1. The results indicate that not only do changes in irradiance and salinity directly influence growth and toxin production but that changes in irradiance affected the influence of salinity.
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  • 71
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    Water resources management 13 (1999), S. 73-84 
    ISSN: 1573-1650
    Keywords: chlorophyll ; growth ; rice crop ; spectral reflectance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract Relations among spectral reflectance, chlorophyll ‘a’, and growth of rice plants grown on irrigated light textured soil in a semi arid region are presented here. There was a linear relation between spectral reflectance and rice plant height (r = 0.97), for band 1 (0.45–0.52 μm) reflectance values. On the other hand, in bands 2 (0.52–0.60 μm) and 3 (0.63–0.69 μm), reflectance values decreased until 70 days after planting (DAP) and then increased during the reproductive phase of the crop. The near infrared band 4 (0.76–0.90 μm) showed a maximum reflectance at 59 DAP (panicle initiation stage) and a decline in reflectance thereafter through maturity. The peak value of IR/R ratio was 16.39 at 62 DAP during the early reproductive phase; thereafter, it declines gradually with the maturity of the crop. Chlorophyll ‘a’ concentration was high during early growth (vegetative and early reproductive stages) and decreased during the flowering and maturity stages. The rice plant canopy show a high chlorophyll ‘a’ concentration at 64 and 59 DAP for sites A and B, respectively. Chlorophyll ‘a’ concentration is higher in site A plant canopies than it is in site B during the entire crop cycle. A good inverse correlation (r = 0.91) has been found between chlorophyll ‘a’ and band 1, while the IR/R ratio and the normalised difference vegetation index (NDVI) showed a relationship (r = 0.78) with the chlorophyll ‘a’ concentration during the crop cycle. Band 2, 3 and 4 radiance values show a biphasic linear relationship with chlorophyll ‘a’ concentrations, negative for early growth and positive for flowering and maturity stages. Results indicate that the period between 66 to 70 DAP is most suitable for the assessment of rice crop yield, based on chlorophyll ‘a’ concentration.
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  • 72
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    Aquaculture international 7 (1999), S. 251-260 
    ISSN: 1573-143X
    Keywords: bacterial biofilm ; common carp (Cyprinus carpio) ; growth ; rohu (Labeo rohita) ; Tilapia (Oreochromis mossambicus)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were conducted to enhance the growth of common carp (Cyprinus carpio), rohu (Labeo rohita) and Mozambique tilapia (Oreochromis mossambicus) through use of sugarcane bagasse as substrate. Bagasse was suspended in water with or without supplementation with fertilizers. Bagasse supplemented with cattle dung and urea favoured higher zooplankton production and significantly (p 〈 0.05) increased fish growth by over 50% compared to bagasse or fertilizers on their own. This higher production of fish is attributed to bacterial biofilm promoted on the substrate which, apart from forming food for zooplankton and fish, contributed to improved water quality by lowering ammonia.
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  • 73
    ISSN: 1573-143X
    Keywords: Convict cichlid (Cichlasoma nigrofasciatum ; environmental UV effects ; growth ; ultraviolet radiation ; UVA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The long term (two generations) effect an enhanced (5%) sub-lethal ultraviolet-A (320–400 nm) irradiation on growth and survival rate of a convict cichlid (Cichlasoma nigrofasciatum is presented. Two UVA irradiated populations (G1-UVA and G2-UVA) and two control populations (G1-control and G2-control) were observed from age 60 to 403 days. The UVA populations were exposed to enhanced UVA irradiation from 4 months of age (G1-UVA and from egg's state (G2-UVA). The specific growth rates (daily weight and length increase) and the condition factors of the populations were not affected by the enhanced UVA, it depended more on the population size. At the adapted temperature range (27–29 °C) the survival rate of those populations was not affected by enhanced UVA. A combined effect of enhanced UVA and increased temperature (31–32 °C) was responsible for a high mortality rate in the GI-UVA. A total of 67% of the G1-UVA population died just within a week of exposure to high temperature.
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  • 74
    ISSN: 1573-143X
    Keywords: body composition ; dietary protein ; fecundity ; gonad maturation ; growth ; Nile tilapia (Oreochromis niloticus)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Six-week-old Nile tilapia (Oreochromis niloticus) fry with an average weight (SD) of 0.51(0.2) g were reared for 140 days on five formulated, isocaloric diets of different protein levels (25, 30, 40 and 45% by dry weight). Fish fed diets of higher protein levels (40 and 45%) showed better growth and feed conversion ratio than those on lower protein levels. Fast-growing fish matured earlier. Maturation rate was affected by the dietary protein levels. Males matured earlier than females: the first mature males were recorded when they were 14 weeks old, whereas the females matured after 18 weeks. In both sexes, mean percentage of mature fish rose with increasing dietary protein level, the percentage of mature males being higher than that of the females. Similarly, the percentage of mature fish rose with the increasing age of fish, with more than 50% males and females mature at the age of 22 and 24 weeks, respectively, the exception being the 25% protein diet fed fish, where the percentage of mature fish was below 50%. In all treatments, spawning was initiated when the fish were 22 weeks old. Smallest size at spawning of males and females was 9.2 cm (13.1 g) and 8.1 cm (8.9 g), respectively, and dietary protein levels influenced the size of fish at first maturity. For both sexes, no difference was found in the gonado-somatic index (GSI) among different treatments. Fecundity increased with increasing dietary protein levels, but significant differences were found only between 40–45% and 25–35% dietary protein levels. The relative fecundity (eggs g−1 female) was higher at the lower dietary protein levels (25–35%) than at the higher dietary protein levels (40–45%). The dietary protein levels did not have any significant influence on the size and weight of mature eggs. The chemical composition of fish and mature ovaries was significantly influenced by the dietary protein level.
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    Aquaculture international 7 (1999), S. 179-187 
    ISSN: 1573-143X
    Keywords: feeding ; growth ; larvae ; micro-algae ; pearl oyster (Pinctada margaritifera L.) ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper reports on an experiment to determine growth and survival of blacklip pearl oyster, Pinctada margaritifera (L.), larvae fed a 1:1 mixture of Isochrysis aff. galbana clone T-ISO and Pavlova salina at six different densities (1, 2, 5, 10, 20 and 30 × 103 cells ml-1. Larval growth and survival were assessed every four days over a 20–day period. Exponential and logistic regression models were fitted to the growth and survival responses, respectively. Overall growth of larvae fed ≥5 × 103 cells ml-1 was significantly greater (p 〉 0.01) than growth of larvae reared at other algal densities. The optimal food ration for maximum larval growth was 20 × 103 cells ml-1, which resulted in larvae with antero-posterior shell length of 230 μm after 20 days. These larvae were significantly larger (p 〉 0.05) than those in all other treatments at the end of the experiment. Survival of larvae fed 0, 1 and 2 × 103 cells ml-1 was significantly lower than that of larvae in all other treatments at the end of 15 days (p 〉 0.01). Maximal survival (8%) over the 20 day period was shown by larvae fed 10 × 103 cells ml-1, while lower survival was shown by larvae fed 2 × 103 cells ml-1 (2%) and 1 × 103 cells ml-1 (0%).
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  • 76
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    Aquaculture international 7 (1999), S. 201-205 
    ISSN: 1573-143X
    Keywords: fingerlings ; growth ; light regimes ; photoperiod ; silver catfish (Rhamdia quelen) ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 77
    ISSN: 1573-143X
    Keywords: gilthead sea bream (Sparus aurata) ; growth ; hybridization ; red porgy (Pagrus pagrus) ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Hybridization between gilthead sea bream, Sparus aurata, and red porgy, Pagrus pagrus, was undertaken and viable hybrids were produced by an artificial hormonal-induced cross. The hybrids, from the cross of female red porgy and male gilthead sea bream (Pp × Sa), survived through the yolk-sac larval stage. The hybrids produced from the cross of female gilthead sea bream and male red porgy (Sa × Pp) presented higher mortality in the larval stage (98.4%) compared to gilthead sea bream (80.0%) and red porgy (92.5%). Afterwards, the Sa × Pp hybrid was compared to the offspring of its parental species under the same rearing conditions (tanks of 500 l capacity, natural light, ambient temperature, self-feeding with commercial feed) in a 40–week experiment. In this comparative study, the Sa × Pp hybrid had intermediate mortality rate (6%), compared to gilthead sea bream (0%) and red porgy (21%). The growth profile of this hybrid resembled the slow growing phases of its parents (red porgy in warm period and gilthead sea bream in cold period). The feed conversion ratio between fish forms was not significantly different (1.54–1.84 in the Sa × Pp hybrid, 1.53–1.56 in the maternal species and 1.33–1.40 in the paternal one). The body weight variation in the Sa × Pp hybrid was quite high (31.7–37.9%), compared to that in gilthead sea bream (19.7–24.7%) and red porgy (18.0–31.3%). With respect to body coloration, the Sa × Pp hybrid was distinguishable and classified into groups of red porgy-like (55.1%), gilthead sea bream-like (40.6%), and intermediate forms (4.3%). The preliminary results of this study proved that the produced Sa × Pp hybrid had too low a performance for aquaculture use, but the interesting consequent hereditary potential could be a useful tool in fish hybridization practice.
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  • 78
    ISSN: 1573-5036
    Keywords: 2 ; 4-D ; germination ; growth ; salinity-tolerance ; seed treatment ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were conducted under laboratory and greenhouse conditions to study the effect of 2,4-D on rooting and salinity tolerance of wheat. Seeds of one commercial wheat (Inqalab-91) and three salt-tolerant wheat lines (WL-41, WL-359, and WL-1073 developed through wide hybridization) were included in the study. Preliminary and short-term experiments were conducted to determine the level of 2,4-D (administered through seed soaking for 24.5 h. at 25 °C in the dark) at which the maximum number of roots emerged. Under hydroponic conditions, 2,4-D treatment of seeds caused an increase of 60 to 100% in the number of primary roots. The maximum increase in the number of roots was observed in one of the salt tolerant wheat lines (WL-41). The roots appeared in bunches but showed stunted growth at higher levels of 2,4-D. Dry matter accumulation decreased markedly; the effect was more pronounced in Inqalab-91 which is less tolerant to stress than other wheat lines. In all wheat types, allocation of dry matter to roots relative to shoot increased due to 2,4-D treatment. In soil, seeds treated with different levels of 2,4-D showed a germination delay of 1–3 days. Although the number of primary roots increased, 2,4-D treatment caused a decrease in total dry matter accumulation by plants grown for 40 days. In another experiment, conducted under greenhouse conditions, seed germination and growth of seedlings was significantly retarded in saline compared to that in non-saline (normal) soil. Initially, the pace of germination of treated seeds as well as seedling growth was slower in both soils, but after six weeks, the leaf area of seedlings raised from treated seeds was greater than those raised from untreated seeds. Towards maturity, plants arising from treated seeds developed wider and longer flag leaves leading to enhanced yield. Root biomass decreased in saline soil as compared to normal soil. However, 2,4-D treatment caused a substantial increase in root biomass in saline soil and the roots were harder in texture in wheats other than Inqalab-91. Seed treatment with 2,4-D led to a significant improvement in the number of productive tillers, yield of straw and grain, and grain protein content of all wheats grown in saline soil. Plants grown in normal soil did not show any marked effect of seed treatment on grain yield and other agronomic parameters. The four wheats showed substantial differences for different parameters but the salt tolerant wheat lines performed better compared to the commercial variety Inqalab-91.
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  • 79
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    Plant and soil 217 (1999), S. 1-15 
    ISSN: 1573-5036
    Keywords: anchorage ; development ; growth ; root systems ; symmetry ; tree stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The stability of shallowly rooted trees can be strongly influenced by the symmetry of the ‘structural’ system of woody roots. Root systems of forest trees are often markedly asymmetric, and many of the factors affecting symmetry, including root initiation and the growth of primary and woody roots, are poorly understood. The internal and environmental factors that control the development, with respect to symmetry and rigidity, of shallow structural root systems are reviewed and discussed with particular reference to Sitka spruce (Picea sitchensis Bong. Carr.). Areas where there is insufficient knowledge are highlighted. A scheme is proposed that represents the root system as a set of spokes that are variable in number, size and radial distribution. Rigidity can vary between and along each of the spokes. The root system is presented as a zone of competition for assimilates, where allocation to individual roots depends upon their position and local variations in conditions. Factors considered include the production of root primordia of different sizes, effects of soil conditions such as the supply of mineral nutrients and water on growth of primary and woody roots, and the effect of forces caused by wind action on growth of the cambium, giving rise to roots which, in cross section, resemble I- or T-beams, and efficiently resist bending.
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  • 80
    ISSN: 1573-5028
    Keywords: aquaporin ; gene expression ; growth ; Oryza sativa ; plasma membrane intrinsic protein (PIP) ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Membrane intrinsic proteins facilitate movement of small molecules often times functioning as water channels. We have identified two genes from rice which encode proteins with characteristic features of plasma membrane intrinsic proteins (PIP). They possess six membrane-spanning domains, an NPA repeat, overall high sequence homologies and characteristic C- and N-terminal hallmark motifs which allowed assignment of OsPIP1a to the PIP1 subfamily and of OsPIP2a to the PIP2 subfamily. OsPIP1a and OsPIP2a showed similar but not identical expression patterns. The two genes were expressed at higher levels in seedlings than in adult plants and expression in the primary root was regulated by light. In internodes of deepwater rice plants which were induced to grow rapidly by submergence, transcript levels were slightly induced in the intercalary meristem (IM) and slightly reduced in the elongation zone (EZ) after 18 h. In internodes of GA-induced excised stem sections transcript levels transiently declined in the IM and EZ after 1 h and subsequently recovered to elevated levels after 18 h. GA also induced OsPIP expression in non-growing tissue after 18 h. In the IM of submergence-induced stem sections transcript levels remained constitutive. The different growth-promoting treatments showed no direct correlation between growth rate and OsPIP gene expression in dividing or expanding cells. In fact, treatment of excised stem sections with ABA or drought stress induced similar changes in OsPIP expression in the growing zone during the first 6 h as GA did. We conclude that regulation of OsPIP1a and OsPIP2a expression is not primarily controlled by growth. GA-induced growth may however change the water status of cells which in turn results in altered PIP abundance.
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    Plant and soil 216 (1999), S. 93-101 
    ISSN: 1573-5036
    Keywords: Acacia cyanophylla ; endomycorrhizae ; growth ; nutrition ; Rhizobia ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The behaviour of Acacia cyanophylla Lind. plants submitted to salinity stress was followed in the greenhouse. The plants were associated with indigenous symbiotic microorganisms isolated from the coastal dunes of the Souss-Massa region. A two months period of salinity had a large negative impact on plant growth and acquisition of macro nutrients. However, the study underlined the role of the microbial inoculum for the plant in the achievement of salt tolerance. An isolate of Bradyrhizobium sp., RCM6 (R1), originating from the Massa dunes, was highly efficient in improving growth and nutrition of the A. cyanophylla. Double inoculation with the rhizobia and an endomycorrhizal complex, isolated from the Lamzar dunes had a clear additional positive effect, i.e. the fungi further increased the tolerance of the A. cyanophylla plants to salinity.
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  • 82
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    New forests 18 (1999), S. 301-314 
    ISSN: 1573-5095
    Keywords: chilling stress ; drought stress recovery ; field performance ; growth ; morphology ; nursery culture ; tree nursery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Five week old white spruce [Picea glauca (Moench) Voss] seedlings were placed within controlled-temperature growth chambers, and subjected to one of four periodic, chilling treatments for approximately 16 weeks. The treatments differed in the frequency of 24 hour exposure to 5 °C the seedlings received, and ranged from no chilling (control), to once every two, three or four days. After 25 weeks of growth, the control seedlings were significantly taller than all chilling-exposed seedlings, but stem diameters were similar. Chilling did not affect either needle length or needle density compared to control seedlings. During a water deficit test, frequently chilling-exposed seedlings maintained significantly higher mid-day shoot water potentials under extreme water stress. Re-watering after the drought resulted in all chilling-treated seedlings recovering faster to pre-stress shoot water potential levels than the control seedlings. Measurements of new root growth after 21 days at 10 °C indicated that previous chilling exposure delayed or inhibited new root production.
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  • 83
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    Plant growth regulation 29 (1999), S. 101-112 
    ISSN: 1573-5087
    Keywords: ABA ; cell wall-associated peroxidase ; expansins ; growth ; pH ; XET
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Over the past decade it has become clear that we cannot always explain the observed reduction in leaf expansion rates during drought by measuring the plant's water relations. This has led us to question the possibility of a role for the cell wall and its biochemical machinery in controlling the rate of leaf expansion during drought. However, if we are to reject or modify previous assumptions regarding the control of leaf expansion during drought, then we must offer alternative explanations. This article addresses recent work from this laboratory and in the literature, concerning the involvement of cell wall-enzymes, pH and abscisic acid (ABA) in regulating leaf expansion during water deficit.
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  • 84
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    Hydrobiologia 392 (1999), S. 205-215 
    ISSN: 1573-5117
    Keywords: Dreissena ; hypoxia ; thermal stratification ; survival ; growth ; distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Experiments and field surveys were conducted in Hargus Lake (Ohio, U.S.) to investigate the effect of lake stratification on the survival, growth and distribution of zebra mussels. During the lake stratification period, relatively stable temperature and dissolved oxygen (DO) gradients persisted across the water column, allowing us to examine the chronic effect of hypoxia on zebra mussels. Zebra mussels were incubated in cages and suspended at different depths in the water column at both pelagic (max. depth = 12 m) and littoral (max. depth = 3.5 m) sites from April 18 to September 28, 1994. No mussel survived to the end of the experiment in cages ≥ 5.5 m, whereas the highest survival rate (76%) occurred at 5 m depth where temperature and DO remained fairly stable for at least 3 months. The threshold oxygen level for survival was between 1.0–1.7 mg l-1 when water temperature was at about 17–18 °C. While zebra mussels′ survival rate was not affected under the sublethal hypoxic conditions, their growth was greatly retarded by poor water quality. The field survey showed that the zebra mussels and macrophytes had about the same distribution and their biomasses were positively related. The percentage of mussels in aggregates increased towards their maximum distribution depth. The maximum distribution depth of the naturally occurring zebra mussels was only 2.8 m, whereas the adult mussels could survive the entire stratification period when being artificially placed on the 3.5 m bottom, and young mussels could colonize the 3.5 m bottom if solid substrates were provided. We conclude that lack of substrate, rather than hypoxia, was the limiting factor of zebra mussel distribution above 5 m depth in Hargus Lake.
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    Hydrobiologia 401 (1999), S. 265-277 
    ISSN: 1573-5117
    Keywords: nucleic acids ; fish larvae ; RNA/DNA ; condition ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nucleic acid analysis has provided useful tools to study recent growth and mortality of young fishes and their responses to environmental variability. The ratio of RNA–DNA (R/D) has been shown to respond to changes in feeding conditions and growth after periods as short as 1–3 days in a variety of fish species. The earliest studies used primarily UV-based methods, but most investigators now use more sensitive, fluorometric dye-binding assays to estimate RNA and DNA in individual larvae. These newer methods are very sensitive to procedural details and choice of standards. Analytical methods, normalization and calibration procedures to optimize information obtained from nucleic acid analysis are discussed. We present examples illustrating the technique's utility, and problems encountered when applying nucleic acid-based indices to fish larvae and early juveniles. The wide use of R/D analysis in studies of fish early life stages, together with a proliferation of analytical methods, demands a major intercalibration exercise.
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  • 86
    ISSN: 1573-5117
    Keywords: zebra mussel ; intermittent halogenation ; Dreissena polymorpha ; growth ; settlement ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of intermittent (2–4 h/day) treatments with chlorine or bromine at levels of 0.5 and 1.0 mg/L (total residual oxidant) upon settling and growth of veliger larvae of the zebra mussel, Dreissena polymorpha, was examined in two successive flow-through studies. The work was conducted in a field laboratory which received a constant supply of water from western Lake Erie. Veliger densities in the water at the field site peaked at 530/L, while mussel densities on settling monitors reached 147,100/m2 over the course of the two studies (early July to late September 1991). In Study 1, a 2-h daily treatment with 1.0 mg/L chlorine reduced mussel settling by 91% as compared with controls, although mussel densities of up to 6,000/m2 still occurred. Treatment with 0.5 mg/L chlorine for 4 h/day produced a similar reduction in mussel settling during the second study. Bromine was less effective than chlorine at reducing settling of veligers. Mussels which remained settled in the treatment tanks had growth rates similar to controls, reaching 2–4 mm in length over a 30-day period. The intermittent halogen treatments similarly had no effect on whole body glycogen levels or growth of adult D. polymorpha. The intermittent chlorination regime used may therefore delay, but would not prevent a mussel fouling problem.
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  • 87
    ISSN: 1573-5117
    Keywords: Gracilaria multipartita ; seasonal variation ; growth ; chemical composition ; agar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The biology and agar composition and properties of Gracilaria multipartita, a common species along the coasts of Morocco, have been studied on samples collected monthly for one year. Growth of the alga was maximum in spring and autumn, and the seaweed partially decayed after its maximum fertility was reached in June and October. The agar content and composition showed seasonal variations. The agar content was maximal in winter (30% dw), and decreased during the growth periods to minima in June and October (25% dw) which also corresponded to the maxima of fertility. The agar composition was characterized by high 6-O-methyl galactose (38–59 mol%) and 3,6 anhydrogalactose (24–39%) contents together with galactose (12.6–25.7 mol%) and sulphate (24–5.0% dw). The gel strength varied between 246 and 511 g cm−2 and increased after alkali treatment to reach a maximum of 880 g cm−2. The gel stre ngth decreased after the alga reached its maxima of fertility, indicating a possible relationship between growth, fertility and agar metabolism. The content and quality of agar from G. multipartita growing in Morocco are suitable for an industrial use of the seaweed for the production of food-grade agar.
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  • 88
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    Environmental biology of fishes 54 (1999), S. 325-336 
    ISSN: 1573-5133
    Keywords: population structure ; reproduction ; growth ; mortality ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Black seabream, Spondyliosoma cantharus, caught off the Canary Islands is characterized by a protogynous hermaphroditism. The size range of the catches is between 8 and 40 cm, with a main distribution between 16 and 24 cm. The mean length of the individuals shows an increase with increasing depth. Males:females ratio is unbalanced in favour of females (1:2.18). The reproductive season extends from late autumn to mid spring, with a peak in spawning activity in January–February. A dichromatism is found between males and females during the spawning season. Males reach maturity at a larger total length, 22.7 cm (3 years old), than females, 17.3 cm (2 years old). Morphometric relationship between length and mass for the whole population is described by the parameters: a=0.00732, and b=3.24747. Otoliths age readings indicate that the exploited population consists of eleven age groups (0–X years), including a very high proportion of individuals between 2 and 3 years old. The von Bertalanffy growth parameters for the whole population are: L∞=43.35 cm, k=0.24 year−1, and t0=−0.11 year. The rates of total, natural and fishing mortality are 1.36, 0.52 and 0.84 year−1, respectively. The length at first capture is 16.8 cm. The exploitation rate indicates that the stock is overfished.
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    Environmental biology of fishes 55 (1999), S. 215-225 
    ISSN: 1573-5133
    Keywords: gonadosomatic index ; growth ; maturity ; migration ; mortality ; sex ratio ; spawning ; von Bertalanffy growth model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aspects of the life history of Labeo cylindricus in Lake Chicamba, a man made hydroelectric dam in central Mozambique were investigated. L. cylindricus was found to be a potadrometic, synchronous spawner concentrating in river mouths prior to migrating up flowing rivers in January to spawn. Length-at-(50%)-maturity was attained at a fork length (FL) of 96 mm for males and 98 mm for females, both within their first year of life. The adult sex ratio was found to be female dominated at 1 male:1.63 females. Scales were used to age the species, with two growth checks deposited annually. Growth was rapid and was best described by the von Bertalanffy growth model as L t =224.2(1−e-0.66(r+0.03)) mm FL. A maximum age of 4 years was observed for L. cylindricus with the largest male and female measuring 210 mm FL and 235 mm FL, respectively. The rate of natural mortality was estimated to be extremely high at 1.93 year-1 using length-converted catch curve analysis and is possibly a response to heavy predation by the introduced piscivore Micropterus salmoides.
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  • 90
    ISSN: 1573-5133
    Keywords: reproduction ; spawning ; age ; growth ; vermilion snapper ; Trinidad ; Tobago
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Reproduction and growth of the vermilion snapper, Rhomboplites aurorubens, were studied in Trinidad and Tobago. The smallest individual caught measured 145 mm total length (TL) and all fish appeared to be mature. It was not possible to precisely determine size at first maturity due to the use of macroscopic techniques. The smallest spent male and female measured 181 and 211 mm TL respectively, suggesting a size at first maturity below these sizes. Spawning occurred throughout the year, with a period of peak spawning from about June to November in the rainy season when river runoff increased. Sagittal otolith sections were used for age determination and the opaque ring, which was counted as the annulus, was deposited from January to May in the dry season. A total of 11 age groups between the ages of 2–12 years (155–505 mm total length) were found. The von Bertalanffy growth parameters were: L∞=532 mm, K=0.13 y−1, and t0=−0.17, where L∞ is the asymptotic length, K is the growth coefficient and t0 is the theoretical age at zero length. The relationship between weight (WT) and length (TL) was WT=3.43×10−5 TL2.82. Vermilion snapper in this study area appears to grow slower and attain a smaller asymptotic length, but has a longer lifespan than found in populations in higher latitudes. This may be attributed to different levels of exploitation, which may be higher in the latter areas.
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  • 91
    ISSN: 1573-5168
    Keywords: growth ; mass spectrometry ; 15N-phenylalanine ; protein synthesis ; stable isotope technology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vivo rates of protein synthesis in fish have predominantly been measured using a single flooding dose injection of a solution containing 3H-Phenylalanine as a tracer. However, use of a radiolabelled tracer restricts the application of this technique to controlled laboratory conditions. In this study, the flooding dose technique was used to successfully measure in vivo rates of protein synthesis in Atlantic salmon (Salmo salar L.) smolts utilising a stable isotope labelled amino acid, L-[15N]-Phenylalanine, as an alternative tracer. Methodologies are presented allowing the 15N enrichment in the free amino acid pool and in body protein to be measured using mass spectrometry. In this study, the fractional rates of protein consumption (kr), synthesis (ks) and growth (kg) of Atlantic salmon smolts (37 ± 1.4 g) were measured as 4.7, 3.3 and 1.6% day−1 respectively. Protein synthesis retention efficiency (kgks) and protein growth efficiency (kgkr)were calculated as 48.5 and 34.0% respectively. The ks, kgks and kgkr values obtained in this study were found to be within the range of values available in the literature for juvenile salmonid fish of a comparable size. The use of L-[15N]-Phenylalanine provides an alternative tracer to radiolabelled amino acids for measuring in vivo rates of protein synthesis in fish using the flooding dose' technique and also allows studies of fish protein metabolism to be carried out in environmentally sensitive (field and laboratory) conditions where the use of radiolabels is prohibited.
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  • 92
    ISSN: 1573-5168
    Keywords: Atlantic salmon ; growth ; individual feed consumption rate ; plasma insulin ; protein synthesis capacity ; trypsin isozymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth was found to be associated with the changes of trypsin activity in the pyloric caecal tissues and the level of plasma insulin in Atlantic salmon (Salmo salar L.). A decrease in trypsin activity accompanied by an increase in plasma insulin was detected one month before an enhanced growth was observed. There were significant relationships between weight specific consumption rate, plasma insulin levels and fish growth. The correlation of weight specific consumption rate was higher with growth rate (R2=0.7, p〈0.0001) than with plasma insulin concentration (R2=0.4, p〈0.0001). When the comparison was made between Atlantic salmon carrying and lacking the trypsin variant TRP-2*92, the fish with the variant had lower maintenance ration (p〈0.05), higher capacity for protein synthesis in the white muscle (p〈0.02), and a greater ability to utilize the feed at a restricted ration than the fish without the variant. In Atlantic salmon lacking the variant, both plasma insulin concentrations and growth rates were significantly lower (p〈0.05) in the fish fed 0.5% bw day−1 than those fed 1% bw day−1. Whilst the growth rates of TRP-2*92 salmon fed the different rations became similar one month after similar levels of plasma insulin were observed between them. The TRP-2*92 salmon may be defined as a high protein growth efficiency fish with low protein turnover rate. Genetic variation in trypsin isozyme pattern affects feed utilization, plasma insulin levels and growth in Atlantic salmon.
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    Journal of economic growth 4 (1999), S. 429-445 
    ISSN: 1573-7020
    Keywords: growth ; R&D ; education ; regime shift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract The role of learning and R&D in economic development is addressed in an endogenous growth model. When human capital is below a threshold level, the model predicts that skills are accumulated as the only growth-generating activity, whereas both innovation activities and learning drive growth above this level. Hence, an endogenous regime shift is triggered when the level of human capital reaches the threshold level because it becomes profitable to innovate.
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    Journal of economic growth 4 (1999), S. 55-80 
    ISSN: 1573-7020
    Keywords: mercantilism ; growth ; taxation ; openness ; familiarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract Nations close themselves voluntarily to varying degrees. Restrictions on the flow of ideas are difficult to understand, since open countries have higher relative incomes. This article provides an explanation based on the existence of two channels of public finance—traditional and mercantilistic. The latter refers to monopoly creation to provide a stream of government revenue. Strong, profitable monopolies require that the nation be closed to new ideas about technology and organization. The government sets the degree of restriction to balance current mercantilistic revenue with future revenue from traditional sources. The model is supported with numerical simulations and historical illustrations.
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    Journal of economic growth 4 (1999), S. 119-137 
    ISSN: 1573-7020
    Keywords: growth ; technology ; Solow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract Growth accounting breaks down economic growth into components associated with changes in factor inputs and the Solow residual, which reflects technological progress and other elements. After a presentation of the standard model, the analysis considers dual approaches to growth accounting (which considers changes in factor prices rather than quantities), spillover effects and increasing returns, taxes, and multiple types of factor inputs. Later sections place the growth-accounting exercise within the context of two recent strands of endogenous growth theory—varieties-of-products models and quality-ladders models. Within these settings, the Solow residual can be interpreted in terms of measures of the endogenously changing level of technology.
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    Journal of economic growth 4 (1999), S. 305-330 
    ISSN: 1573-7020
    Keywords: growth ; convergence clubs ; poverty trap ; cultural factors ; location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract This study investigates the sources of heterogeneity across a worldwide set of countries. Unspecified ex ante and unanticipated cultural (Protestant versus Catholic), geographical (continents), and institutional (OECD versus non-OECD) clubs emerge endogenously and naturally as homogeneous classes on the basis of their economic structure. The dynamics both within and across the identified groups of countries are consistent with multiple equilibrium-growth models proposed by, for instance, Azariadis and Drazen (1990), therefore strengthening the viability of the convergence club hypothesis. In particular, higher stages of development are, on average, non linearly associated with higher stages of growth.
    Type of Medium: Electronic Resource
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  • 97
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    Journal of economic growth 4 (1999), S. 81-111 
    ISSN: 1573-7020
    Keywords: growth ; investment ; regimes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract The absence of continuous regime type measures that focus on institutions rather than outcomes besets studies on whether democratic or authoritarian regimes grow faster. Additional shortcomings include the failure to consider development stages and the erroneous endogenous specification of regimes. Given panel data on 105 countries from 1960 to 1989, the effective party/constitutional framework measure does not correlate with growth or investment in the total sample. But considering development levels, some evidence indicates that discretion decreases growth in advanced areas, and, contrary to theory, inhibits investment in poorer countries. Also, single-party dictatorships have higher investment ratios but do not grow faster than party-less regimes.
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  • 98
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    Journal of economic growth 4 (1999), S. 213-232 
    ISSN: 1573-7020
    Keywords: education ; work experience ; self-employment ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract We examine the implications for growth and development of the existence of two types of human capital: entrepreneurial and professional. Entrepreneurs accumulate human capital through a work-experience intensive process, whereas professionals’ human capital accumulation is education-intensive. Moreover, the return to entrepreneurship is uncertain. We show how skill-biased technological progress leads to changes in the composition of aggregate human capital; as technology improves, individuals devote less time to the accumulation of human capital through work experience and more to the accumulation of human capital through professional training. Thus, our model explains why entrepreneurs play a relatively more important role in intermediate-income countries and professionals are relatively more abundant in richer economies. It also shows that those countries that initially have too little of either entrepreneurial or professional human capital may end up in a development trap.
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  • 99
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    Journal of economic growth 4 (1999), S. 331-349 
    ISSN: 1573-7020
    Keywords: growth ; fertility ; income distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract This article analyzes the interaction between growth and fertility via income distribution in a model in which fertility decisions are motivated by old-age support. It provides an explanation of the demographic transition of an economy from a stage of increasing fertility and low growth to a stage of low fertility, high human capital investments, and high growth.
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  • 100
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    Review of industrial organization 14 (1999), S. 391-396 
    ISSN: 1573-7160
    Keywords: Fate ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract Fate bringeth economic growth and malfeasance giveth its gains
    Type of Medium: Electronic Resource
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