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  • Wiley  (239,464)
  • American Geophysical Union  (53,975)
  • 2010-2014  (191,750)
  • 1995-1999  (101,689)
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  • 1
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    Evolution of temperature, O3, CO, and N2O profiles during the exceptional 2009 Arctic major stratospheric warming as observed by lidar and mm-wave spectroscopy at Thule (76.5°N, 68.8°W), Greenland. (2010)
    American Geophysical Union
    Details
    Publication Date: 2020-12-18
    Description: The 2009 Arctic sudden stratospheric warming (SSW) was the most intense event of this kind ever observed. Unique ground-based measurements of middle atmospheric profiles for temperature, O3, CO, and N2O obtained at Thule (76.5°N, 68.8°W), Greenland, in the period January – early March are used to show the evolution of the 2009 SSW in the region of its maximum intensity. The first sign of the SSW was detected at θ~2000 K on January 19, when a rapid decrease in CO mixing ratio took place. The first evidence of a temperature increase was observed at the same level on 22 January, the earliest date on which lidar measurements reached above ~50 km. The warming propagated from the upper to the lower stratosphere in 7 days and the record maximum temperature of 289 K was observed between 1300 and 1500 K potential temperature on 22 January. A strong vortex splitting was associated with the SSW. Stratospheric backward trajectories indicate that airmasses arriving to Thule during the warming peak underwent a rapid compression and an intense adiabatic warming of up to 50 K. The rapid advection of air from the extra-tropics was also occasionally observed to produce elevated values of N2O mixing ratio. Starting from mid-February the temperature profile and the N2O mixing ratio returned to the pre-warming values in the mid and upper stratosphere, indicating the reformation of the vortex at these levels. In late winter, vertical descent from starting altitudes of ~60 km is estimated from CO profiles to be 0.25±0.05 km/day.
    Description: Published
    Description: D24315
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: open
    Keywords: sudden stratospheric warming ; winter polar stratosphere ; temperature ; O3 ; N2O ; CO ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure ; 01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 2
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    The September 26, 1997 Colfiorito, Italy Earthquakes: modeled coseismic surface displacement from SAR interferometry and GPS (2012)
    American Geophysical Union
    Details
    Publication Date: 2021-05-25
    Description: The largest events of the 1997 Umbria-Marche sesimic sequence were the two September 26 earthquakes of Mw=5.7 (00:33 GMT) and Mw=6.0 (09:40 GMT), which caused severe damage and ground cracks in a wide area around the epicenters. We created an ERS-SAR differenrtial interferogram, where nine fringes are visible in and around the Colfiorito basin, corresponding to 25 cm of coseismic surface dispalacements. GPS data show a maximum horizontal displacement...
    Description: Published
    Description: 883-886
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: restricted
    Keywords: Colfiorito, SAR, GPS ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
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  • 3
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    Early-middle Holocene land snail shell stable isotope record from Grotta di Latronico 3 (southern Italy) (2011)
    Wiley
    Details
    Publication Date: 2021-04-07
    Description: This paper compares stable isotope (δ18O and δ13C) records of early–middle Holocene land snail shells from the archaeological deposits of Grotta di Latronico 3 (LTR3; southern Italy) with modern shell isotopic data. No substantial interspecific variability was observed in shell δ18O (δ18Os) of modern specimens (Pomatias elegans, Cornu aspersum, Eobania vermiculata, Helix ligata and Marmorana fuscolabiata). In contrast, interspecific shell δ13C (δ13Cs) variability was significant, probably due to different feeding behaviour among species. The δ18Os values of living land snails suggest that species hibernate for a long period during colder months, so that the signal of 18O-depleted winter rainfall in their δ18Os is lost. This suggests that δ18Os and δ13Cs values of Pomatias elegans from this archaeological succession provide valuable clues for seasonal (spring–autumn) climatic conditions during the early–middle Holocene. The δ18Os values of fossil specimens are significantly lower than in modern shells and in agreement with other palaeoclimatic records, suggesting a substantial increase of precipitation and/or persistent changes in air mass source trajectories over this region between ca. 8.8 cal ka BP and 6.2–6.7 ka ago. The δ13Cs trend suggests a transition from a slightly 13C-enriched to a 13C-depleted diet between early and middle Holocene compared to present conditions. We postulate that this δ13Cs trend might reflect changes in the C3 vegetation community, potentially combined with other environmental factors such as regional moisture increase and the progressive decrease of atmospheric CO2 concentration. Copyright © 2010 John Wiley & Sons, Ltd.
    Description: Published
    Description: 1347-1359
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: reserved
    Keywords: central Mediterranean ; archaeological succession ; land snail shells ; stable isotopes ; palaeoclimate ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    An unloading foam model to constrain Etna’s 11–13 January 2011 lava fountaining episode (2011)
    American Geophysical Union
    Details
    Publication Date: 2021-06-09
    Description: The 11–13 January 2011 eruptive episode at Etna volcano occurred after several months of increasing ash emissions from the summit craters, and was heralded by increasing SO2 output, which peaked at ∼5000 megagrams/day several hours before the start of the eruptive activity. The eruptive episode began with a phase of Strombolian activity from a pit crater on the eastern flank of the SE‐Crater. Explosions became more intense with time and eventually became transitional between Strombolian and fountaining, before moving into a lava fountaining phase. Fountaining was accompanied by lava output from the lower rim of the pit crater. Emplacement of the resulting lava flow field, as well as associated lava fountain‐ and Strombolian‐phases, was tracked using a remote sensing network comprising both thermal and visible cameras. Thermal surveys completed once the eruptive episode had ended also allowed us to reconstruct the emplacement of the lava flow field. Using a high temporal resolution geostationary satellite data we were also able to construct a detailed record of the heat flux during the fountain‐fed flow phase and its subsequent cooling. The dense rock volume of erupted lava obtained from the satellite data was 1.2 × 106 m3; this was emplaced over a period of about 6 h to give a mean output rate of ∼55 m3 s−1. By comparison, geologic data allowed us to estimate dense rock volumes of ∼0.85 × 106 m3 for the pyroclastics erupted during the lava fountain phase, and 0.84–1.7 × 106 m3 for lavas erupted during the effusive phase, resulting in a total erupted dense rock volume of 1.7–2.5 × 106 m3 and a mean output rate of 78–117 m3 s−1. The sequence of events and quantitative results presented here shed light on the shallow feeding system of the volcano.
    Description: Published
    Description: B11207
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: partially_open
    Keywords: Etna ; lava fountains ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 5
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    A year of lava fountaining at Etna: Volumes from SEVIRI (2012)
    American Geophysical Union
    Details
    Publication Date: 2021-06-09
    Description: We present a new method that uses cooling curves, apparent in high temporal resolution thermal data acquired by geostationary sensors, to estimate erupted volumes and mean output rates during short lava fountaining events. The 15 minute temporal resolution of the data allows phases of waxing and peak activity to be identified during short (150-to- 810 minute-long) events. Cooling curves, which decay over 8-to-21 hour-periods following the fountaining event, can also be identified. Application to 19 fountaining events recorded at Etna by MSG’s SEVIRI sensor between 10 January 2011 and 9 January 2012, yields a total erupted dense rock lava volume of 28 106 m3, with a maximum intensity of 227 m3 s 1 being obtained for the 12 August 2011 event. The timeaveraged output over the year was 0.9 m3 s 1, this being the same as the rate that has characterized Etna’s effusive activity for the last 40 years.
    Description: We are grateful to EUMETSAT for SEVIRI data.
    Description: Published
    Description: L06305
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: restricted
    Keywords: satellite ; lava fountains ; Etna ; erupted volume ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Turbulent times in the northern polar ionosphere? (2011)
    American Geophysical Union
    Details
    Publication Date: 2020-12-03
    Description: A model is presented of the growth rate of turbulently generated irregularities in the electron concentration of northern polar cap plasma patches. The turbulence is generated by the short‐term fluctuations in the electric field imposed on the polar cap ionosphere by electric field mapping from the magnetosphere. The model uses an ionospheric imaging algorithm to specify the state of the ionosphere throughout. The growth rates are used to estimate mean amplitudes for the irregularities, and these mean amplitudes are compared with observations of the scintillation indices S4 and s by calculating the linear correlation coefficients between them. The scintillation data are recorded by GPS L1 band receivers stationed at high northern latitudes. A total of 13 days are analyzed, covering four separate magnetic storm periods. These results are compared with those from a similar model of the gradient drift instability (GDI) growth rate. Overall, the results show better correlation between the GDI process and the scintillation indices than for the turbulence process and the scintillation indices. Two storms, however, show approximately equally good correlations for both processes, indicating that there might be times when the turbulence process of irregularity formation on plasma patches may be the controlling one.
    Description: Published
    Description: A04310
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: restricted
    Keywords: ionospheric irregularities ; scintillations ; Gradient Drift Instability ; 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics ; 01. Atmosphere::01.02. Ionosphere::01.02.07. Scintillations ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Synchronization between tides and sustained oscillations of the hydrothermal system of Campi Flegrei (Italy) (2013)
    American Geophysical Union
    Details
    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
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  • 8
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    Mapping Moho depth variations in central Italy from PsMoho-P delay times: Evidence of an E-W transition in the Adriatic Moho at 42°N latitude (2014)
    American Geophysical Union
    Details
    Publication Date: 2020-12-18
    Description: Along the Italian peninsula adjoin two crustal domains, peri-Tyrrhenian and Adriatic, whose boundary is not univocal in central Italy. In this area, we attempt to map the extent of the Moho in the two terrains from variations of the travel time difference between the direct P wave and the P-to-S wave converted at the crust-mantle boundary, called PsMoho. We use teleseismic receiver functions computed at 38 broad-band stations in this and previous studies, and assigned each of the recording sites to the Adriatic or peri-Tyrrhenian terrains based on station location, geologic and geophysical data and interpretation, and consistency of delays with the regional Moho trend. The results of the present study show that the PsMoho arrival time varies from 2.3 to 4.1 s in the peri-Tyrrhenian domain and from 3.7 to 5.5 s in the Adriatic domain. As expected, the lowest time difference is observed along the Tyrrhenian coastline and the largest values are observed in the axial zone of the Apennine chain. A key new result of this study is a sharp E-W boundary in the Adriatic domain that separates a deeper Moho north of about 42 N latitude from a shallower Moho to the south. This feature is constrained for a length of about 40 km by the observations available in this study. The E-W boundary requires a revision of prior mapping of the Moho in central Italy and supports previous hypotheses of lithosphere segmentation.
    Description: Published
    Description: 3929–3938
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: open
    Keywords: teleseismic receiver functions ; Moho discontinuity ; central Italy ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 9
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    Low-temperature magnetic properties of pelagic carbonates: Oxidation of biogenic magnetite and identification of magnetosome chains (2014)
    American Geophysical Union
    Details
    Publication Date: 2021-02-17
    Description: Pelagic marine carbonates provide important records of past environmental change. We carried out detailed low-temperature magnetic measurements on biogenic magnetite-bearing sediments from the Southern Ocean (Ocean Drilling Program (ODP) Holes 738B, 738C, 689D, and 690C) and on samples containing whole magnetotactic bacteria cells. We document a range of low-temperature magnetic properties, including reversible humped low-temperature cycling (LTC) curves. Different degrees of magnetite oxidation are considered to be responsible for the observed variable shapes of LTC curves. A dipole spring mechanism in magnetosome chains is introduced to explain reversible LTC curves. This dipole spring mechanism is proposed to result from the uniaxial anisotropy that originates from the chain arrangement of biogenic magnetite, similar to published results for uniaxial stable single domain (SD) particles. The dipole spring mechanism reversibly restores the remanence during warming in LTC measurements. This supports a previous idea that remanence of magnetosome chains is completely reversible during LTC experiments. We suggest that this magnetic fingerprint is a diagnostic indicator for intact magnetosome chains, although the presence of isolated uniaxial stable SD particles and magnetically interacting particles can complicate this test. Magnetic measurements through the Eocene section of ODP Hole 738B reveal an interval with distinct magnetic properties that we interpret to originate from less oxidized biogenic magnetite and enrichment of a biogenic “hard” component. Co-occurrence of these two magnetic fingerprints during the late Eocene in the Southern Ocean indicates less oxic conditions, probably due to increased oceanic primary productivity and organic carbon burial.
    Description: Published
    Description: 6049–6065
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: pelagic carbonates ; biogenic magnetite ; rock magnetism ; environmental magnetism ; ODP ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    A retrospective comparative forecast test on the 1992 Landers sequence (2012)
    American Geophysical Union
    Details
    Publication Date: 2021-06-16
    Description: We perform a retrospective forecast experiment on the 1992 Landers sequence comparing the predictive power of commonly used model frameworks for short‐term earthquake forecasting. We compare a modified short‐term earthquake probability (STEP) model, six realizations of the epidemic‐type aftershock sequence (ETAS) model, and four models that combine Coulomb stress changes calculations and rate‐and‐state theory to generate seismicity rates (CRS models). We perform the experiment under the premise of a controlled environment with predefined conditions for the testing region and data for all modelers. We evaluate the forecasts with likelihood tests to analyze spatial consistency and the total amount of forecasted events versus observed data. We find that (1) 9 of the 11 models perform superior compared to a simple reference model, (2) ETAS models forecast the spatial evolution of seismicity best and perform best in the entire test suite, (3) the modified STEP model matches best the total number of events, (4) CRS models can only compete with empirical statistical models by introducing stochasticity in these models considering uncertainties in the finite‐fault source model, and (5) resolving Coulomb stress changes on 3‐D optimally oriented planes is more adequate for forecasting purposes than using the specified receiver fault concept. We conclude that statistical models perform generally better than the tested physics‐based models and parameter value updates using the occurrence of aftershocks generally improve the predictive power in particular for the purely statistical models in space and time.
    Description: Published
    Description: B05305
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: earthquake forecast ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability
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  • 11
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    Birth of an ocean in the Red Sea: Initial pangs (2012)
    American Geophysical Union
    Details
    Publication Date: 2021-07-14
    Description: We obtained areal variations of crustal thickness, magnetic intensity, and degree of melting of the sub- axial upwelling mantle at Thetis and Nereus Deeps, the two northernmost axial segments of initial oceanic crustal accretion in the Red Sea, where Arabia is separating from Africa. The initial emplacement of oceanic crust occurred at South Thetis and Central Nereus roughly $2.2 and $2 Ma, respectively, and is taking place today in the northern Thetis and southern Nereus tips. Basaltic glasses major and trace element com- position suggests a rift-to-drift transition marked by magmatic activity with typical MORB signature, with no contamination by continental lithosphere, but with slight differences in mantle source composition and/or potential temperature between Thetis and Nereus. Eruption rate, spreading rate, magnetic intensity, crustal thickness and degree of mantle melting were highest at both Thetis and Nereus in the very initial phases of oceanic crust accretion, immediately after continental breakup, probably due to fast mantle upwelling enhanced by an initially strong horizontal thermal gradient. This is consistent with a rift model where the lower continental lithosphere has been replaced by upwelling asthenosphere before continental rupturing, implying depth-dependent extension due to decoupling between the upper and lower lithosphere with man- tle-lithosphere-necking breakup before crustal-necking breakup. Independent along-axis centers of upwell- ing form at the rifting stage just before oceanic crust accretion, with buoyancy-driven convection within a hot, low viscosity asthenosphere. Each initial axial cell taps a different asthenospheric source and serves as nucleus for axial propagation of oceanic accretion, resulting in linear segments of spreading.
    Description: Published
    Description: Q08009
    Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: partially_open
    Keywords: Red Sea ; Gravity and Magnetics ; magma genesis and partial melting ; mantle processes ; transition from continental to oceanic rift ; 04. Solid Earth::04.03. Geodesy::04.03.04. Gravity anomalies ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics
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  • 12
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    Shallow subduction beneath Italy: Three-dimensional images of the Adriatic-European-Tyrrhenian lithosphere system based on high-quality P wave arrival times (2010)
    American Geophysical Union
    Details
    Publication Date: 2020-10-26
    Description: This paper presents a velocity model of the Italian (central Mediterranean) lithosphere in unprecedented detail. The model is derived by inverting a set of 166,000 Pg and Pn seismic wave arrival times, restricted to the highest-quality data available. The tomographic images reveal the geometry of the subduction-collision system between the European, Adriatic, and Tyrrhenian plates, over a larger volume and with finer resolution than previous studies. We find two arcs of low-Vp anomalies running along the Alps and the Apennines, describing the collision zones of underthrusting continental lithospheres. Our results suggest that in the Apennines, a significant portion of the crust has been subducted below the mountain belt. From the velocity model we can also infer thermal softening of the crustal wedge above the subducting Adriatic plate. In the Tyrrhenian back-arc region, strong and extensive low-Vp anomalies depict upwelling asthenospheric material. The tomographic images also allow us to trace the boundary between the Adriatic and the Tyrrhenian plates at Moho depth, revealing some tears in the Adriatic-Ionian subducting lithosphere. The complex lithospheric structure described by this study is the result of a long evolution; the heterogeneities of continental margins, lithospheric underthrusting, and plate indentation have led to subduction variations, slab tears, and asthenospheric upwelling at the present day. The high-resolution model provided here greatly improves our understanding of the central Mediterranean’s structural puzzle. The results of this study can also shed light on the evolution of other regions experiencing both oceanic and continental subduction.
    Description: Published
    Description: B05305
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: open
    Keywords: lithosphere ; crust ; italy ; plates ; subduction ; europe ; seismicity ; adria ; tyrrhenian ; boundary ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
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  • 13
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    Three-dimensional Moho topography in Italy: New constraints from receiver functions and controlled source seismology (2012)
    American Geophysical Union
    Details
    Publication Date: 2020-10-26
    Description: In complex tectonics regions, seismological, geophysical, and geodynamic modeling require accurate definition of the Moho geometry. Various active and passive seismic experiments performed in the central Mediterranean region revealed local information on the Moho depth, in some cases used to produce interpolated maps. In this paper, we present a new and original map of the 3-D Moho geometry obtained by integrating selected high-quality controlled source seismic and teleseismic receiver function data. The very small cell size makes the retrieved model suitable for detailed regional studies, crustal corrections in teleseismic tomography, advanced 3-D ray tracing in regional earthquake location, and local earthquake tomography. Our results show the geometry of three different Moho interfaces: the European, Adriatic-Ionian, and Tyrrhenian. The three distinct Moho are fashioned following the Alpine and Apennines subduction, collision, and back-arc spreading and show medium- to high-frequency topographic undulations reflecting the complexity of the geodynamic evolution.
    Description: Published
    Description: Q09006
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Italy; controlled source seismology; crust; receiver function ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 14
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    Syn-convergent extension observed using the RETREAT GPS network, northern Apennines, Italy (2012)
    American Geophysical Union
    Details
    Publication Date: 2020-11-25
    Description: We present crustal deformation results from a geodetic experiment (Retreating-Trench, Extension, and Accretion Tectonics (RETREAT)) focused on the northern Apennines orogen in Italy. The experiment centers on 33 benchmarks measured with GPS annually or more frequently between 2003 and 2007, supplemented by data from an additional older set of 6 campaign observations from stations in northern Croatia, and 187 continuous GPS stations within and around northern Italy. In an attempt to achieve the best possible estimates for rates and their uncertainties, we estimate and filter common mode signals and noise components using the continuous stations and apply these corrections to the entire data set, including the more temporally limited campaign time series. The filtered coordinate time series data are used to estimate site velocity. We also estimate spatially variable seasonal site motions for stations with sufficient data. The RMS scatter of residual time series are generally near 1 mm and 4 mm, horizontal and vertical, respectively, for continuous and most of the new campaign stations, but scatter is slightly higher for some of the older campaign data. Velocity uncertainties are below 1 mm/yr for all but one of the stations. Maximum rates of site motion within the orogen exceed 3 mm/yr (directed NE) relative to stable Eurasia. This motion is accommodated by extension within the southwestern and central portions of the orogen, and shortening across the foreland thrust belt to the northeast of the range. The data set is consistent with contemporaneous extension and shortening at nearly equal rates. The northern Apennines block moves northeast faster than the Northern Adria microplate. Convergence between the Northern Apennines block and the Northern Adria microplate is accommodated across a narrow zone that coincides with the northeastern Apennines range front. Extension occurs directly above an intact vertically dipping slab inferred by previous authors from seismic tomography. The observed crustal deformation is consistent with a buried dislocation model for crustal faulting, but associations between crustal motion and seismically imaged mantle structure may also provide new insights on mantle dynamics.
    Description: Published
    Description: B04408
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: GPS, northern Apennines, retreat, Italy ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
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  • 15
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    Sudden deep gas eruption nearby Rome's airport of Fiumicino (2014)
    American Geophysical Union
    Details
    Publication Date: 2021-03-24
    Description: On 24 August 2013 a sudden gas eruption from the ground occurred in the Tiber river delta, nearby Rome's international airport of Fiumicino. We assessed that this gas, analogous to other minor vents in the area, is dominantly composed of deep, partially mantle-derived CO2, as in the geothermal gas of the surrounding Roman Comagmatic Province. Increased amounts of thermogenic CH4 are likely sourced from Meso-Cenozoic petroleum systems, overlying the deep magmatic fluids. We hypothesize that the intersection of NE-SW and N-S fault systems, which at regional scale controls the location of the Roman volcanic edifices, favors gas uprising through the impermeable Pliocene and deltaic Holocene covers. Pressurized gas may temporarily be stored below these covers or within shallower sandy, permeable layers. The eruption, regardless the triggering cause—natural or man-made, reveals the potential hazard of gas-charged sediments in the delta, even at distances far from the volcanic edifices.
    Description: Published
    Description: 5632–5636
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: geothermal gas ; deep CO2 ; Tiber river delta ; thermogenic CH4 ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
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  • 16
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    Relation between subduction megathrust earthquakes, trench sediment thickness and upper plate strain (2012)
    American Geophysical Union
    Details
    Publication Date: 2021-06-16
    Description: Giant earthquake (moment magnitude Mw 〉=8.5) forecasts for subduction zones have been empirically related to both tectonic stresses and geometrical irregularities along the subduction interface. Both of these controls have been suggested as able to tune the ability of rupture to propagate laterally and, in turn, exert an important control on giant earthquake generation. Here we test these hypotheses, and their combined influence, by compiling a dataset of trench fill thickness (a proxy for smoothing of subducting plate relief by sediment input into the subduction channel) and upper plate strain (a proxy for the tectonic stresses applied to the subduction interface) for 44 segments of the global subduction network. We statistically compare relationships between upper plate strain, trench sediment thickness and maximal earthquake magnitude. We find that the combination of both large trench fill (≥1 km) and neutral upper plate strain explains spatial patterns of giant earthquake occurrence to a statistically significant degree. In fact, the concert of these two factors is more highly correlated with giant earthquake occurrence than either factor on its own. Less frequent giant earthquakes of lower magnitude are also possible at subduction zones with thinner trench fill and compressive upper plate strain. Extensional upper plate strain and trench fill 〈 0.5 km appear to be unfavorable conditions, as giant earthquakes have not been observed in these geodynamical environments during the last 111 years.
    Description: Published
    Description: L05304
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: open
    Keywords: subduction zones ; trench sediment thickness ; Upper plate strain ; megathrust earthquakes ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    Magnetic and seismic reflection study of Lake Cheko, a possible impact crater for the 1908 Tunguska Event (2012)
    American Geophysical Union
    Details
    Publication Date: 2021-06-07
    Description: A major explosion occurred on 30 June 1908 in the Tunguska region of Siberia, causing the destruction of over 2,000 square km of taiga; pressure and seismic waves detected as far as 1,000 km away; bright luminescence in the night skies of Northern Europe and Central Asia; and other unusual phenomena. This “Tunguska Event” is probably related to the impact with the Earth of a cosmic body that exploded about 5-10 km above ground, releasing in the atmosphere 10-15 Mton of energy. Fragments of the impacting body have never been found, and its nature (comet or asteroid) is still a matter of debate. We report here results from a magnetic and seismic-reflection study of a small (~500 m diameter) lake, Lake Cheko, located about 8 km NW of the inferred explosion epicenter, that was proposed to be an impact crater left by a fragment of the Tunguska Cosmic Body. Seismic-reflection and magnetic data revealed a P-wave velocity/magnetic anomaly close to the lake center, about 10 m below the lake floor; this anomaly is compatible with the presence of a buried stony object and supports the impact crater origin for Lake Cheko.
    Description: Published
    Description: Q05008
    Description: 3.4. Geomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Tunguska ; Lake Cheko ; Central Siberia ; Impact cratering ; magnetometry ; seismic reflection ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
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    Discovery of a gliding salt-detached megaslide, Calabria, Ionian Sea, Italy (2013)
    American Geophysical Union
    Details
    Publication Date: 2020-11-26
    Description: Integrating seismic reflection profiles, well logs, and field evidence with GPS velocities from a network installed in Calabria, southern Italy, we have discovered that the Crotone basin is gliding toward the Ionian Sea over a buried viscous salt layer. This previously unknown megaslide (~1000 km2) is characterized by an onshore updip extensional domain and an offshore downdip toe-thrust rim. The GPS velocity from the Crotone station is significantly higher than velocities from other stations in the region and differently oriented. We ascribe at least part of the anomalous GPS velocity from the Crotone station to the seaward motion of the megaslide or part of it. From the GPS velocity and other evidence we obtain a viscosity of the buried salt layer within the known range of rock salt viscosity in nature.
    Description: Published
    Description: 4220-4224
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: seismic reflection profiles ; Calabria ; salt ; landslide ; GPS ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology
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  • 19
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    Periodic volcanic degassing behavior: The Mount Etna example (2013)
    American Geophysical Union
    Details
    Publication Date: 2021-06-25
    Description: In contrast to the seismic and infrasonic energy released from quiescent and erupting volcanoes, which have long been known to manifest episodes of highly periodic behavior, the spectral properties of volcanic gas flux time series remain poorly constrained, due to a previous lack of hightemporal resolution gas-sensing techniques. Here we report on SO2 flux measurements, performed on Mount Etna with a novel UV imaging technique of unprecedented sampling frequency (0.5 Hz), which reveal, for the first time, a rapid periodic structure in degassing from this target. These gas flux modulations have considerable temporal variability in their characteristics and involve two period bands: 40–250 and 500–1200 s. A notable correlation between gas flux fluctuations in the latter band and contemporaneous seismic root-mean-square values suggests that this degassing behavior may be generated by periodic bursting of rising gas bubble trains at the magma-air interface.
    Description: Published
    Description: 4818–4822
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: SO2 flux ; UV camera ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 20
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    Remote sensing of aerosols in the Arctic for an evaluation of global climate model simulations (2014)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Atmospheres, Wiley, 119(13), pp. 8169-8188, ISSN: 0148-0227
    Details
    Publication Date: 2020-03-05
    Description: In this study MODerate resolution Imaging Spectroradiometer (MODIS) Aqua retrievals of aerosol optical thickness (AOT) at 555 nm are compared to sun-photometer measurements from Svalbard for a period of 9 years. For the 642 daily coincident measurements that were obtained, MODIS AOT generally varies within the predicted uncertainty of the retrieval over ocean (ΔAOT = ±0.03 ± 0.05 · AOT). The results from the remote sensing have been used to examine the accuracy in estimates of aerosol optical properties in the Arctic, generated by global climate models and from in-situ measurements at the Zeppelin station, Svalbard. AOT simulated with the Norwegian Earth System Model (NorESM1-M)/ CAM4-Oslo global climate model does not reproduce the observed seasonal variability of the Arctic aerosol. The model overestimates clear-sky AOT by nearly a factor of 2 for the background summer season, while tending to underestimate the values in the spring season. Furthermore, large differences in all-sky AOT of up to one order of magnitude are found for the Coupled Model Intercomparison Project (CMIP5) model ensemble for the spring and summer seasons. Large differences between satellite/ground-based remote sensing of AOT and AOT estimated from dry and humidified scattering coefficients are found for the subarctic marine boundary layer in summer.
    Repository Name: EPIC Alfred Wegener Institut
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  • 21
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    Climate sensitivity across marine domains of life: limits to evolutionary adaptation shape species interactions (2014)
    Wiley
    In:  EPIC3Global Change Biology, Wiley, ISSN: 1365-2486
    Details
    Publication Date: 2019-07-16
    Description: Organisms in all domains, Archaea, Bacteria, and Eukarya will respond to climate change with differential vulnerabilities resulting in shifts in species distribution, coexistence, and interactions. The identification of unifying principles of organism functioning across all domains would facilitate a cause and effect understanding of such changes and their implications for ecosystem shifts. For example, the functional specialization of all organisms in limited temperature ranges leads us to ask for unifying functional reasons. Organisms also specialize in either anoxic or various oxygen ranges, with animals and plants depending on high oxygen levels. Here, we identify thermal ranges, heat limits of growth, and critically low (hypoxic) oxygen concentrations as proxies of tolerance in a meta-analysis of data available for marine organisms, with special reference to domain-specific limits. For an explanation of the patterns and differences observed, we define and quantify a proxy for organismic complexity across species from all domains. Rising complexity causes heat (and hypoxia) tolerances to decrease from Archaea to Bacteria to uni- and then multicellular Eukarya. Within and across domains, taxon-specific tolerance limits likely reflect ultimate evolutionary limits of its species to acclimatization and adaptation. We hypothesize that rising taxon-specific complexities in structure and function constrain organisms to narrower environmental ranges. Low complexity as in Archaea and some Bacteria provide life options in extreme environments. In the warmest oceans, temperature maxima reach and will surpass the permanent limits to the existence of multicellular animals, plants and unicellular phytoplankter. Smaller, less complex unicellular Eukarya, Bacteria, and Archaea will thus benefit and predominate even more in a future, warmer, and hypoxic ocean.
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  • 22
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    Potential effects of climate change on the distribution range of the main silicate sinker of the Southern Ocean (2014)
    Wiley
    In:  EPIC3Ecology and Evolution, Wiley, 4(16), pp. 3147-3161, ISSN: 2045-7758
    Details
    Publication Date: 2014-09-24
    Description: Fragilariopsis kerguelensis, a dominant diatom species throughout the Antarctic Circumpolar Current, is coined to be one of the main drivers of the biological silicate pump. Here, we study the distribution of this important species and expected consequences of climate change upon it, using correlative species distribution modeling and publicly available presence-only data. As experience with SDM is scarce for marine phytoplankton, this also serves as a pilot study for this organism group. Southern Ocean. We used the maximum entropy method to calculate distribution models for the diatom F. kerguelensis based on yearly and monthly environmental data (sea surface temperature, salinity, nitrate and silicate concentrations). Observation data were harvested from GBIF and the Global Diatom Database, and for further analyses also from the Hustedt Diatom Collection (BRM). The models were projected on current yearly and seasonal environmental data to study current distribution and its seasonality. Furthermore, we projected the seasonal model on future environmental data obtained from climate models for the year 2100. Projected on current yearly averaged environmental data, all models showed similar distribution patterns for F. kerguelensis. The monthly model showed seasonality, for example, a shift of the southern distribution boundary toward the north in the winter. Projections on future scenarios resulted in a moderately to negligibly shrinking distribution area and a change in seasonality. We found a substantial bias in the publicly available observation datasets, which could be reduced by additional observation records we obtained from the Hustedt Diatom Collection. Present day distribution patterns inferred from the models coincided well with background knowledge and previous reports about F. kerguelensis distribution, showing that maximum entropy-based distribution models are suitable to map distribution patterns for oceanic planktonic organisms. Our scenario projections indicate moderate effects of climate change upon the biogeography of F. kerguelensis.
    Repository Name: EPIC Alfred Wegener Institut
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  • 23
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    A first Glimpse at the genome of the Baikalian amphipod Eulimnogammarus verrucosus (2014)
    Wiley
    In:  EPIC3Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, Wiley, 322(3), pp. 177-189, ISSN: 1552-5007
    Details
    Publication Date: 2014-07-21
    Description: Eulimnogammarus verrucosus is an amphipod endemic to the unique ecosystem of Lake Baikal and serves as an emerging model in ecotoxicological studies. We report here on a survey sequencing of its genome as a first step to establish sequence resources for this species. From a single lane of paired-end sequencing data, we estimated the genome size as nearly 10 Gb and we obtained an overview of the repeat content. At least two-thirds of the genome are non-unique DNA, and a third of the genomic DNA is composed of just five families of repetitive elements, including low-complexity sequences. Attempts to use off-the-shelf assembly tools failed on the available low-coverage data both before and after removal of highly repetitive components. Using a seed-based approach we nevertheless assembled short contigs covering 33 pre-microRNAs and the homeodomain-containing exon of nine Hox genes. The absence of clear evidence for paralogs implies that a genome duplication did not contribute to the large genome size. We furthermore report the assembly of the mitochondrial genome using a new, guided “crystallization” procedure. The initial results presented here set the stage for a more complete sequencing and analysis of this large genome.
    Repository Name: EPIC Alfred Wegener Institut
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  • 24
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    Latent heat exchange in the boreal and arctic biomes (2014)
    Wiley
    In:  EPIC3Global Change Biology, Wiley, pp. n/a–n/a, ISSN: 1365-2486
    Details
    Publication Date: 2021-07-19
    Description: In this study latent heat flux (λE) measurements made at 65 boreal and arctic eddy-covariance (EC) sites were analyses by using the Penman–Monteith equation. Sites were stratified into nine different ecosystem types: harvested and burnt forest areas, pine forests, spruce or fir forests, Douglas-fir forests, broadleaf deciduous forests, larch forests, wetlands, tundra and natural grasslands. The Penman–Monteith equation was calibrated with variable surface resistances against half-hourly eddy-covariance data and clear differences between ecosystem types were observed. Based on the modeled behavior of surface and aerodynamic resistances, surface resistance tightly control λE in most mature forests, while it had less importance in ecosystems having shorter vegetation like young or recently harvested forests, grasslands, wetlands and tundra. The parameters of the Penman–Monteith equation were clearly different for winter and summer conditions, indicating that phenological effects on surface resistance are important. We also compared the simulated λE of different ecosystem types under meteorological conditions at one site. Values of λE varied between 15% and 38% of the net radiation in the simulations with mean ecosystem parameters. In general, the simulations suggest that λE is higher from forested ecosystems than from grasslands, wetlands or tundra-type ecosystems. Forests showed usually a tighter stomatal control of λE as indicated by a pronounced sensitivity of surface resistance to atmospheric vapor pressure deficit. Nevertheless, the surface resistance of forests was lower than for open vegetation types including wetlands. Tundra and wetlands had higher surface resistances, which were less sensitive to vapor pressure deficits. The results indicate that the variation in surface resistance within and between different vegetation types might play a significant role in energy exchange between terrestrial ecosystems and atmosphere. These results suggest the need to take into account vegetation type and phenology in energy exchange modeling.
    Repository Name: EPIC Alfred Wegener Institut
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  • 25
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    Linear Weakening of the AMOC in response to Receding Glacial Ice Sheets in CCSM3 (2014)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 41(17), pp. 6252-6258, ISSN: 0094-8276
    Details
    Publication Date: 2019-07-17
    Description: The transient response of the Atlantic Meridional Overturning Circulation (AMOC) to a deglacial ice-sheet retreat is studied using the Community Climate System Model version 3 (CCSM3), with a focus on orographic effects rather than meltwater discharge. It is found that the AMOC weakens significantly (41%) in response to the deglacial ice-sheet retreat. The AMOC weakening follows the decrease of the Northern Hemisphere ice-sheet volume linearly, with no evidence of abrupt thresholds. A wind-driven mechanism is proposed to explain the weakening of the AMOC: lowering the Northern Hemisphere ice sheets induces a northward shift of the westerlies, which causes a rapid eastward sea-ice transport and expanded sea-ice cover over the subpolar North Atlantic; this expanded sea ice insulates the ocean from heat loss and leads to suppressed deep convection and a weakened AMOC. A sea ice-ocean positive feedback could be further established between the AMOC decrease and sea-ice expansion.
    Repository Name: EPIC Alfred Wegener Institut
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  • 26
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    Assimilating SMOS sea ice thickness into a coupled ice-ocean model using a local SEIK filter (2014)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Oceans, Wiley, ISSN: 0148-0227
    Details
    Publication Date: 2019-07-17
    Description: The impact of assimilating sea ice thickness data derived from ESA's Soil Moisture and Ocean Salinity (SMOS) satellite together with Special Sensor Microwave Imager/Sounder (SSMIS) sea ice concentration data of the National Snow and Ice Data Center (NSIDC) in a coupled sea ice-ocean model is examined. A period of 3 months from 1 November 2011 to 31 January 2012 is selected to assess the forecast skill of the assimilation system. The 24 h forecasts and longer forecasts are based on the Massachusetts Institute of Technology general circulation model (MITgcm), and the assimilation is performed by a localized Singular Evolutive Interpolated Kalman (LSEIK) filter. For comparison, the assimilation is repeated only with the SSMIS sea ice concentrations. By running two different assimilation experiments, and comparing with the unassimilated model, independent satellite-derived data, and in situ observation, it is shown that the SMOS ice thickness assimilation leads to improved thickness forecasts. With SMOS thickness data, the sea ice concentration forecasts also agree better with observations, although this improvement is smaller.
    Repository Name: EPIC Alfred Wegener Institut
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  • 27
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    Atlantic Water advection versus sea-ice advances in the eastern Fram Strait during the last 9 ka: Multiproxy evidence for a two-phase Holocene (2013)
    American Geophysical Union
    In:  EPIC3Paleoceanography, American Geophysical Union, 28(2), pp. 283-295, ISSN: 1944-9186
    Details
    Publication Date: 2019-07-16
    Description: A sediment core from the West Spitsbergen continental margin was studied to reconstruct climate and paleoceanographic variability during the last ~9 ka in the eastern Fram Strait (FS). Our multiproxy evidence suggests that the establishment of the modern oceanographic configuration in the eastern FS occurred stepwise, in response to the postglacial sea-level rise and the related onset of modern sea-ice production on the shallow Siberian shelves. The late Early and Mid-Holocene interval (9 to 5 ka) was generally characterized by relatively unstable conditions. High abundance of the subpolar planktic foraminifer species Turborotalita quinqueloba implies strong intensity of Atlantic Water (AW) inflow with high productivity and/or high AW temperatures, resulting in a strong heat flux to the Arctic. A series of short-lived cooling events (8.2, 6.9, and 6.1 ka) occurred superimposed on the warm late Early to Mid-Holocene conditions. Our proxy data imply that simultaneous to the complete postglacial flooding of Arctic shallow shelves and the initiation of modern sea-ice production, strong advance of polar waters initiated modern oceanographic conditions in the eastern FS at ~5.2 ka. The Late Holocene was marked by the dominance of the polar planktic foraminifer species Neogloboquadrina pachyderma, a significant expansion of sea ice/icebergs, and strong stratification of the water column. Although planktic foraminiferal assemblages as well as sea subsurface temperatures suggest a return of slightly strengthened advection of subsurface AW after 3 ka, a relatively stable cold-water layer prevailed at the sea surface, and the study site was probably located within the seasonally fluctuating marginal ice zone during the Neoglacial period.
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  • 28
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    Marine ice sheets of Pleistocene age on the East Siberian Continental Margin (2013)
    American Geophysical Union
    In:  EPIC3AGU Fall Meeting, 2013-12-08-2013-12-13American Geophysical Union
    Details
    Publication Date: 2016-02-02
    Description: Based on swath bathymetry, sediment echosounding, seismic profiling and sediment coring we present results of the RV „Polarstern“ cruise ARK-XIII/3 (2008) and RV "Araon" cruise ARA02B (2012), which investigated an area between the Chukchi Borderland and the East Siberian Sea between 165°W and 170°E. At the southern end of the Mendeleev Ridge, close to the Chukchi and East Siberian shelves, evidence is found for the existence of Pleistocene ice sheets/ice shelves, which have grounded several times in up to 1200 m present water depth. We found mega-scale glacial lineations associated with deposition of glaciogenic wedges and debris-flow deposits indicative of sub-glacial erosion and deposition close to the former grounding lines. Glacially lineated areas are associated with large-scale erosion, accentuated by a conspicuous truncation of pre-glacial strata typically capped with mostly thin layers of diamicton draped by pelagic sediments. Our tentative age model suggests that the youngest and shallowest grounding event of an ice sheet should be within Marine Isotope Stage (MIS) 3. The oldest and deepest event predates MIS 6. According to our results, ice sheets of more than one km in thickness continued onto, and likely centered over, the East Siberian Shelf. They were possibly linked to previously suggested ice sheets on the Chukchi Borderland and the New Siberian Islands. We propose that the ice sheets extended northward as thick ice shelves, which grounded on the Mendeleev Ridge to an area up to 78°N within MIS 5 and/or earlier. These results have important implication for the former distribution of thick ice masses in the Arctic Ocean during the Pleistocene. They are relevant for global sea-level variations, albedo, ocean-atmosphere heat exchange, freshwater export from the Arctic Ocean at glacial terminations and the formation of submarine permafrost. The existence of km-thick Pleistocene ice sheets in the western Arctic Ocean during glacial times predating that of the Last Glacial Maximum (LGM) also implies significantly different atmospheric circulation patterns, in particular availability and distribution of moisture during pre-LGM glaciations.
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  • 29
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    Seismostratigraphy of the Siberian Sector of the Arctic Ocean and adjacent Laptev Sea Shelf (2014)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Solid Earth, Wiley, 119(7), pp. 5275-5289, ISSN: 2169-9356
    Details
    Publication Date: 2014-08-18
    Description: A new seismostratigraphic model has been established within the Arctic Ocean adjacent to the East Siberian Shelf on the basis of multichannel seismic reflection data acquired along a transect at 81°N. Ages for the sedimentary units were estimated via links to seismic lines and drill site data of the US Chukchi Shelf, the Lomonosov Ridge, and the adjacent Laptev Shelf. Two distinct seismic units were mapped throughout the area and are the constraints for dating the remaining strata. The lower marker unit, a pronounced high-amplitude reflector sequence (HARS), is the most striking stratigraphic feature over large parts of the Arctic Ocean. It indicates a strong and widespread change in deposition conditions. Probably, it developed during Oligocene times when a reorientation of Arctic Plates took place, accompanied by the gradual opening of the Fram Strait, and a widespread regression of sea level. The top of the HARS likely marks the end of Oligocene/early Miocene (23Ma). An age estimate for the base of the sequence is less clear but likely corresponds to base of Eocene (˜56Ma). The second marked unit detected on the seismic lines parallels the seafloor with a thickness of about 200ms two-way travel time (160 m). Its base is marked by a change from a partly transparent sequence with weak amplitude reflections below to a set of continuous high-amplitude reflectors above. This interface likely marks the transition to large-scale glaciation of the northern hemisphere and therefore is ascribed to the top Miocene (5.3 Ma).
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  • 30
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    Linking Sea Ice Physical Properties with Under-Ice and In-Ice Ecosystems (2012)
    American Geophysical Union
    In:  EPIC3AGU Fall Meeting, San Francisco, Calif., USA, 2012-12-03-2012-12-07American Geophysical Union
    Details
    Publication Date: 2019-07-17
    Description: Impacts of climate change have been most pronounced in Polar Regions. Most alarming is the accelerating decline in Arctic sea ice cover. The changing ice cover has implications for sea ice-associated ecosystems because they rely largely on carbon produced by ice-associated algae. In order to fully understand these ecosystems and to be able to accurately represent them in models there is a need to understand both the physical and biological components of the system. The study presented here is part of AWI’s research group Iceflux which takes an interdisciplinary approach to quantify the trophic carbon flux within sea ice associated ecosystems in the Arctic and Antarctic. Here we will present preliminary results from the ARK XXVII/3 Polarstern Cruise. Biological samples were acquired from the under-ice surface waters using the Surface and Under-Ice Trawl (SUIT) and from within the sea ice by extracting ice cores. To characterize the biophysical properties of the sea ice and under-ice environments several sensors were mounted on the SUIT including: spectral radiometer, ADCP, CTD, fluorometer, altimeter (distance to ice bottom) and video camera. Observations include ice thickness, biological diversity, biomass, light transmission, under-ice water properties and chlorophyll a content (in- and under-ice). Preliminary results will provide a description of the local- to meso-scale spatial variability of biological abundance in and under the ice and the relationship with different sea ice characteristics. During the cruise testing of sensors and equipment will be conducted in order to prepare for the deployment of two Autonomous Bio-Physical Sea Ice Observatories (ABiPSO) stations in the Weddell Sea during the ANT XXIX/6 cruise June 2013. A description of the ABiPSO system and testing of the sensors will be presented highlighting the objectives, challenges and lessons learned.
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  • 31
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    Subglacial roughness of the former Barents Sea ice sheet (2013)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Earth Surface, Wiley, 118(4), pp. 2546-2556, ISSN: 0148-0227
    Details
    Publication Date: 2016-11-15
    Description: The roughness of a glacier bed has high importance for the estimation of the sliding velocity and can also provide valuable insights into the dynamics and history of ice sheets, depending on scale. Measurement of basal properties in present-day ice sheets is restricted to ground-penetrating radar and seismics, with surveys retrieving relatively coarse data sets. Deglaciated areas, like the Barents Sea, can be surveyed by shipborne 2-D and 3-D seismics and multibeam sonar and provide the possibility of studying the basal roughness of former ice sheets and ice streams with high resolution. Here, for the first time, we quantify the subglacial roughness of the former Barents Sea ice sheet by estimating the spectral roughness of the basal topography. We also make deductions about the past flow directions by investigating how the roughness varies along a 2-D line as the orientation of the line changes. Lastly, we investigate how the estimated basal roughness is affected by the resolution of the basal topography data set by comparing the spectral roughness along a cross section using various sampling intervals. We find that the roughness typically varies on a similar scale as for other previously marine-inundated areas in West Antarctica, with subglacial troughs having very low roughness, consistent with fast ice flow and high rates of basal erosion. The resolution of the data set seems to be of minor importance when comparing roughness indices calculated with a fixed profile length. A strong dependence on track orientation is shown for all wavelengths, with profiles having higher roughness across former flow directions than along them.
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  • 32
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    The Arctic Ocean in summer: A quasi-synoptic inverse estimate of boundary fluxes and water mass transformation (2012)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Oceans, Wiley, 117, ISSN: 0148-0227
    Details
    Publication Date: 2017-01-26
    Repository Name: EPIC Alfred Wegener Institut
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  • 33
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    Effects of transient bottom water currents and oxygen concentrations on benthic exchange rates as assessed by eddy correlation measurements (2013)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Oceans, Wiley, 118, pp. 1-13, ISSN: 0148-0227
    Details
    Publication Date: 2017-01-30
    Repository Name: EPIC Alfred Wegener Institut
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  • 34
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    A modern pollen-climate calibration set from central-western Mongolia and its application to a late glacial-Holocene record (2014)
    Wiley
    In:  EPIC3Journal of Biogeography, Wiley, 41(10), pp. 1909-1922, ISSN: 03050270
    Details
    Publication Date: 2019-08-23
    Description: Aim Fossil pollen spectra from lake sediments in central and western Mongolia have been used to interpret past climatic variations, but hitherto no suitable modern pollen–climate calibration set has been available to infer past climate changes quantitatively. We established such a modern pollen dataset and used it to develop a transfer function model that we applied to a fossil pollen record in order to investigate: (1) whether there was a significant moisture response to the Younger Dryas event in north-western Mongolia; and (2) whether the early Holocene was characterized by dry or wet climatic conditions. Location Central and western Mongolia. Methods We analysed pollen data from surface sediments from 90 lakes. A transfer function for mean annual precipitation (Pann) was developed with weighted averaging partial least squares regression (WA-PLS) and applied to a fossil pollen record from Lake Bayan Nuur (49.98° N, 93.95° E, 932 m a.s.l.). Statistical approaches were used to investigate the modern pollen–climate relationships and assess model performance and reconstruction output. Results Redundancy analysis shows that the modern pollen spectra are characteristic of their respective vegetation types and local climate. Spatial autocorrelation and significance tests of environmental variables show that the WA-PLS model for Pann is the most valid function for our dataset, and possesses the lowest root mean squared error of prediction. Main conclusions Precipitation is the most important predictor of pollen and vegetation distributions in our study area. Our quantitative climate reconstruction indicates a dry Younger Dryas, a relatively dry early Holocene, a wet mid-Holocene and a dry late Holocene.
    Repository Name: EPIC Alfred Wegener Institut
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    Lattice-Boltzmann modeling of the air permeability of polar firn (2010)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Earth Surface, Wiley, 115, pp. F04032, ISSN: 0148-0227
    Details
    Publication Date: 2016-11-14
    Description: Recent advances in three‐dimensional (3D) imaging of snow and firn combined with numerical modeling of flow through complex geometries have greatly improved the ability to predict permeability values based on microstructure. In this work, we combined 3D reconstructions of polar firn microstructure obtained from microcomputed tomography (mCT) and a 3D lattice‐Boltzmann (LB) model of air flow. We compared the modeled results to measurements of permeability for polar firn with a wide range of grain and pore‐scale characteristics. The results show good agreement between permeability measurements and calculated permeability values from the LB model over a wide range of sample types. The LB model is better at predicting measured permeability values than traditional empirical equations for polar firn.
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  • 36
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    Complex network of channels beneath an Antarctic ice shelf (2014)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 41(4), pp. 1209-1215, ISSN: 0094-8276
    Details
    Publication Date: 2016-11-15
    Description: Ice shelves play an important role in stabilizing the interior grounded ice of the large ice sheets. The thinning of major ice shelves observed in recent years, possibly in connection to warmer ocean waters coming into contact with the ice-shelf base, has focused attention on the ice-ocean interface. Here we reveal a complex network of sub ice-shelf channels under the Fimbul Ice Shelf, Antarctica, mapped using ground-penetrating radar over a 100 km2 grid. The channels are 300–500 m wide and 50 m high, among the narrowest of any reported. Observing narrow channels beneath an ice shelf that is mainly surrounded by cold ocean waters, with temperatures close to the surface freezing point, shows that channelized basal melting is not restricted to rapidly melting ice shelves, indicating that spatial melt patterns around Antarctica are likely to vary on scales that are not yet incorporated in ice-ocean models.
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    Variability of Arctic sea-ice topography and its impact on the atmospheric surface drag (2014)
    Wiley
    In:  EPIC3Journal of Geophysical Research: Oceans, Wiley, 119(10), pp. 6743-6762, ISSN: 2169-9291
    Details
    Publication Date: 2014-11-27
    Description: Over the polar oceans, near-surface atmospheric transport of momentum is strongly influenced by sea-ice surface topography. The latter is analyzed on the basis of laser altimeter data obtained during airborne campaigns between 1995 and 2011 over more than 10,000 km of flight distance in different regions of the Arctic Ocean. Spectra of height and spacing between topographic features averaged over 10 km flight sections show that typical values are 0.45 m for the mean height and about 20 m for the mean spacing. Nevertheless, the variability is high and the spatial variability is stronger than the temporal one. The total topography spectrum is divided into a range with small obstacles (between 0.2 m and 0.8 m height) and large obstacles (≥0.8 m). Results show that large pressure ridges represent the dominant topographic feature only along the coast of Greenland. In the Central Arctic, the concentration of large ridges decreased over the years, accompanied by an increase of small obstacles concentration and this might be related to decreasing multiyear ice. The application of a topography-dependent parameterization of neutral atmospheric drag coefficients reflects the large variability in the sea-ice topography and reveals characteristic differences between the regions. Based on the analysis of the two spectral ranges, we find that the consideration of only large pressure ridges is not enough to characterize the roughness degree of an ice field, and the values of drag coefficients are in most regions strongly influenced by small obstacles.
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  • 38
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    Late summer net community production in the central Arctic Ocean using multiple approaches (2014)
    Wiley
    In:  EPIC3Global Biogeochemical Cycles, Wiley, 28(10), pp. 1129-1148, ISSN: 0886-6236
    Details
    Publication Date: 2014-11-17
    Description: Large-scale patterns of net community production (NCP) were estimated during the late summer cruise ARK-XXVI/3 (TransArc, August/September 2011) to the central Arctic Ocean. Several approaches were used based on the following: (i) continuous measurements of surface water oxygen to argon ratios (O2/Ar), (ii) underway measurements of surface partial pressure of carbon dioxide (pCO2), (iii) discrete samples of dissolved inorganic carbon, and (iv) dissolved inorganic nitrogen and phosphate. The NCP estimates agreed well within the uncertainties associated with each approach. The highest late summer NCP (up to 6 mol C m-2) was observed in the marginal sea ice zone region. Low values (〈1 mol C m-2) were found in the sea ice-covered deep basins with a strong spatial variability. Lowest values were found in the Amundsen Basin and moderate values in the Nansen and Makarov Basins with slightly higher estimates over the Mendeleev Ridge. Our findings support a coupling of NCP to sea ice coverage and nutrient supply and thus stress a potential change in spatial and temporal distribution of NCP in a future Arctic Ocean. To follow the evolution of NCP in space and time, it is suggested to apply one or several of these approaches in shipboard investigations with a time interval of 3 to 5 years.
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  • 39
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    Autonomous observations of solar energy partitioning in first-year sea ice in the Arctic Basin (2014)
    Wiley
    In:  EPIC3Journal of Geophysical Research: Oceans, Wiley, 119(3), pp. 2066-2080, ISSN: 2169-9291
    Details
    Publication Date: 2014-11-14
    Description: A Spectral Radiation Buoy (SRB) was developed to autonomously measure the spectral incident, reflected, and transmitted spectral solar radiation (350-800 nm) above and below sea ice. The SRB was deployed on drifting first-year sea ice near the North Pole in mid-April 2012, together with velocity and ice mass balance buoys. The buoys drifted southward and reached Fram Strait after approximately 7 months, covering a complete melt season. At the SRB site, snowmelt started on 10 June, and had completely disappeared by 14 July. Surface albedo was above 0.85 until snowmelt onset and decreased rapidly with the progression of snowmelt. Albedo was lowest on 14 July, when the observed surface was likely a mixture of bare ice and melt pond(s). The transmitted irradiance measured under the ice was largest in July, with a monthly average of 20 W m(-2), compared to 〈0.3 W m(-2) premelt. Under-ice irradiance peaked on 19-20 July, with a daily average around 35 W m(-2). From mid-April to mid-September, the solar energy transmitted through the ice into the ocean contributed about two-thirds of the energy required for the observed bottom melt (0.49 m). The energy absorbed by the ice after snowmelt was enough to melt an additional 0.1 m of ice. Solar energy incident on open water and melt ponds provided significant additional heating, indicating solar heating could explain all of the observed bottom melt in this region in summer 2012.
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  • 40
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    Interlaboratory study for coral Sr/Ca and other element/Ca ratio measurements (2013)
    Wiley
    In:  EPIC3Geochemistry Geophysics Geosystems, Wiley, 14(9), pp. 3730-3750, ISSN: 1525-2027
    Details
    Publication Date: 2015-10-21
    Repository Name: EPIC Alfred Wegener Institut
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  • 41
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    A crustal model for northern Melville Bay, Baffin Bay (2014)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Solid Earth, Wiley, 119(119), pp. 8610-8632, ISSN: 0148-0227
    Details
    Publication Date: 2016-12-16
    Description: The interpretation of seismic refraction and gravity data acquired in 2010 gives new insights into the crustal structure of the West Greenland coast and the adjacent deep central Baffin Bay basin. Underneath Melville Bay, the depth of the Moho varies between 26 to 17 km. Stretched continental crust with a thickness of 25 to 14 km and deep sedimentary basins are present in this area. The deep Melville Bay Graben contains an up to ~11km thick infill of consolidated and unconsolidated sediments with velocities of 1.6 to 4.9 km/s. Seawards, at the ~60 km wide transition between oceanic and stretched continental crust, a mount-shaped magmatic structure is observed, which most likely formed prior to the initial formation of oceanic crust. The up to 4 km high magmatic structure is underlain by a ~2 km thick and ~50 km wide high velocity lower crust. More to the west, in the oceanic part of the Baffin Bay basin, we identify a 2-layered, 3.5 to 6 km thin igneous oceanic crust with increasing thickness toward the shelf. Beneath the oceanic crust, the depth of the Moho ranges between 11.5 and 13.5 km. In the western part of the profile, oceanic layer 3 is unusually thin (~1.5 km) A possible explanation for the thin crust is accretion due to slow spreading, although the basement is notably smooth compared to the basement of other regions formed by ultra-slow spreading. The oceanic crust is underlain by partly serpentinized upper mantle with velocities of 7.6 to 7.8 km/s.
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  • 42
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    Assessing the potential of calcium-based artificial ocean alkalinization to mitigate rising atmospheric CO2and ocean acidification (2013)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 40, pp. 1-6, ISSN: 0094-8276
    Details
    Publication Date: 2019-07-17
    Description: Enhancement of ocean alkalinity using calcium compounds, e.g., lime has been proposed to mitigate further increase of atmospheric CO2 and ocean acidification due to anthropogenic CO2 emissions. Using a global model, we show that such alkalinization has the potential to preserve pH and the saturation state of carbonate minerals at close to today’s values. Effects of alkalinization persist after termination: Atmospheric CO2 and pH do not return to unmitigated levels. Only scenarios in which large amounts of alkalinity (i.e., in a ratio of 2:1 with respect to emitted CO2) are added over large ocean areas can boost oceanic CO2 uptake sufficiently to avoid further ocean acidification on the global scale, thereby elevating some key biogeochemical parameters, e.g., pH significantly above preindustrial levels. Smaller-scale alkalinization could counteract ocean acidification on a subregional or even local scale, e.g., in upwelling systems. The decrease of atmospheric CO2 would then be a small side effect.
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  • 43
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    Seasonally different carbon flux changes in the Southern Ocean in response to the southern annular mode (2014)
    Wiley
    In:  EPIC3Global Biogeochemical Cycles, Wiley, 27(4), pp. 1236-1245, ISSN: 0886-6236
    Details
    Publication Date: 2017-01-27
    Description: Stratospheric ozone depletion and emission of greenhouse gases lead to a trend of the Southern Annular Mode (SAM) towards its high-index polarity. The positive phase of the SAM is characterised by stronger than usual westerly winds that induce changes in the physical carbon transport. Changes in the natural carbon budget of the upper 100 m of the Southern Ocean in response to a positive SAM phase are explored with a coupled ecosystem-general circulation model and regression analysis. Previously overlooked processes that are important for the upper ocean carbon budget during a positive SAM period are identified, namely export production and downward transport of carbon north of the Polar Front (PF) as large as the upwelling in the south. The limiting micronutrient iron is brought into the surface layer by upwelling and stimulates phytoplankton growth and export production, but only in summer. This leads to a drawdown of carbon and less summertime outgassing (or more uptake) of natural CO2. In winter, biological mechanisms are inactive and the surface ocean equilibrates with the atmosphere by releasing CO2. In the annual mean, the upper ocean region south of the PF loses more carbon by additional export production than by the release of CO2 into the atmosphere, highlighting the role of the biological carbon pump in response to a positive SAM event.
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  • 44
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    Fracture Mechanical Analysis of Cracks in Ice Shelves using the Finite Element Method and Configurational Forces (2011)
    Wiley
    In:  EPIC3Proceedings in Applied Mathematics and Mechanics, Wiley, 11(1), pp. 169-170, ISSN: 16177061
    Details
    Publication Date: 2017-11-13
    Description: Ice shelves are important elements of the climate system and sensitive to climate changes. The disintegration of large Antarctic ice shelves is the focus of this fracture mechanical analysis. Ice is a complex material which, depending on the context, can be seen as a viscous fluid or as an elastic solid. A fracture event usually occurs on a rather short time scale, thus the elastic response is important and linear elastic fracture mechanics can be used. The investigation of the stress intensity factor as a measure of crack tip loading is based on a 2-dimensional analysis of a single crack with a mode-I type load and additional body loads. This investigation is performed using configurational forces. Depth dependent density and temperature profiles are considered. The relevant parameters are obtained by literature, remote sensing data analysis and modeling of the ice dynamics. The criticality of wet surface cracks is investigated.
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  • 45
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    Analysis of Calving Events in Antarctic Ice Shelves Using Configurational Forces (2012)
    Wiley
    In:  EPIC3Proceedings in Applied Mathematics and Mechanics, Wiley, 12(1), pp. 155-156, ISSN: 16177061
    Details
    Publication Date: 2017-11-13
    Description: Previous studies on the sensitivity of cracks in ice shelves with different boundary conditions, stress states and density profiles revealed the need for further analyses. As the transfer of boundary conditions from dynamic ice flow simulations to the linear elastic fracture analyses proved to be a critical point in previous studies, a new approach to relate viscous and elastic material behaviour is proposed. The numerical simulations are conducted using Finite Elements utilizing the concept of configurational forces. To show the applicability of the approach, a 2-dimensional plane stress geometry with volume loads due to the ice shelf flow is analyzed. The resulting crack path is compared to available crack paths from satellite images.
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  • 46
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    A Law for Small Scale, Continuous Calving (2014)
    Wiley
    In:  EPIC3Proceedings in Applied Mathematics and Mechanics, Wiley, 14(1), pp. 431-432, ISSN: 16177061
    Details
    Publication Date: 2017-11-13
    Description: Ice shelves are formed by the viscous flow of inland ice into the ocean, they are floating and loosing mass by iceberg calving. There are two different kinds of calving: large tabular icebergs detach as singular events in time, and small scale calving occuring on a rather continuous time scale. Three visco-elastic approaches are discussed, in order to derive a general law for calving rates applicable to small scale calving. The results are highly dependent on the termination criterium for each approach, hence the computed calving rate has to be adapted and validated with measurements to get the most qualified value.
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  • 47
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    Finite Element Simulation of Frost Wedging in Ice Shelves (2014)
    Wiley
    In:  EPIC3Proceedings in Applied Mathematics and Mechanics, Wiley, 14(1), pp. 141-142, ISSN: 16177061
    Details
    Publication Date: 2017-11-13
    Description: Break-up events in ice shelves have been studied extensively during the last years. One popular assumption links disintegration events to surface melting of the ice shelf in conjunction with growing melt-water ponds, leading to hydro-fracture. As this explanation only holds during warm seasons [1], the possibility of frost wedging as forcing mechanism for autumn and winter break-up events is considered. Frost wedging can only occur if a closed ice lid seals the water inside the crack. Hence, the present study of frost wedging in a single crack uses ice lid thicknesses to evaluate the additional pressure on the crack faces. The investigation of the resulting stress intensity factor as a measure of crack criticality follows consequently. The results show that freezing water inside a crack can result in unstable crack growth of an initially stable water filled crack.
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  • 48
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    High resolution velocity structure beneath Mount Vesuvius from seismic array data (2011)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: A high resolution P-wave image of Mt. Vesuvius edifice has been derived from simultaneous inversion of travel times and hypocentral parameters of local earthquakes, land based shots and small aperture array data. The results give detailsdownto300 – 500m.Therelocatedlocalseismicity appears to extend down to 5 km below the central crater, distributed in a major cluster, centered at 3 km below the central crater and in a minor group, with diffuse hypocenters inside the volcanic edifice. The two clusters are separated by an anomalously high Vp region at around 1 km depth. A zone with high Vp/Vs in the upper layers is interpreted as produced by the presence of intense fluid circulation. The highest energy quakes (up to M = 3.6) are located in the deeper cluster, in a high P-wave velocity zone. Our results favor an interpretation in terms of absence of shallow magma reservoirs.
    Description: Published
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Velocity Tomography ; Mt. Vesuvius ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
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    Topography of the Calabria subduction zone (southern Italy): Clues for the origin of Mt. Etna (2011)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: Calabria represents an ideal site to analyze the topography of a subduction zone as it is located on top of a narrow active Wadati-Benioff zone and shows evidence of rapid uplift. We analyzed a pattern of surface deformation using elevation data with different filters and showed the existence of a long wavelength (〉100 km) relatively positive topographic signal at the slab edges. The elevation of MIS 5.5 stage marine terraces supports this pattern, although the record is incomplete and partly masked by the variable denudation rate. We performed structural analyses along the major active or recently reactivated normal faults showing that the extensional direction varies along the Calabrian Arc and laterally switches from arc-normal, within the active portion of the slab, to arc-oblique or even arc-parallel, along the northern and southern slab edges. This surface deformation pattern was compared with a recent high resolution P wave tomographic model showing that the high seismic velocity anomaly is continuous only within the active Wadati-Benioff zone, whereas the northern and southwestern sides are marked by low velocity anomalies, suggesting that large-scale topographic bulges, volcanism, and uplift could have been produced by mantle upwelling. We present numerical simulations to visualize the three-dimensional mantle circulation around a narrow retreating slab, ideally similar to the one presently subducting beneath Calabria. We emphasize that mantle upwelling and surface deformation are expected at the edges of the slab, where return flows may eventually drive decompression melting and the Mount Etna volcanism.
    Description: Published
    Description: TC1003
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: topography ; Calabrian Arc ; subduction ; tomography ; mantle flow ; uplift ; retreat ; anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 50
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    The 16 November 2006 flank collapse of the south-east crater at Mount Etna, Italy: Study of the deposit and hazard assessment (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: On 16 November 2006 a flank collapse affected the unstable eastern slope of the South-East Crater (SEC) of Mount Etna. The collapse occurred during one of the paroxysmal events with sustained strombolian activity that characterized the August–December 2006 eruption and was triggered by erosion of loose, hydrothermally altered material of the steep south-east sector of SEC from the outpour of lava. The collapse produced a debris avalanche that involved both lithic and juvenile material and resulted in a deposit emplaced on the eastern flank of the volcano up to 1.2 km away from the source. The total volume of the deposit was estimated to be in the order of 330,000–413,000 m3. The reconstruction of the collapse event was simulated using TITAN2D software designed to model granular avalanches and landslides. This approach can be used to estimate areas that may be affected by similar collapse events in the future. The area affected by the 16 November 2006 lateral collapse of SEC was a small portion of the Mount Etna summit area, but the fact that no one was killed or injured should be considered fortuitous. The summit and adjacent areas of the volcano, in fact, are usually visited by many tourists who are not prepared to face this type of danger. The 16 November 2006 collapse points to the need to be prepared for similar events through scientific investigation (analysis of flank instability, numerical simulation of flows) and development of specific civil protection plans.
    Description: Published
    Description: B02204
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Mount Etna ; flank instability ; volcaniclastic deposit ; granular flows ; numerical simulation ; volcanic hazard ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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    Seismic and landslide source of the 1908 Straits of Messina tsunami (Sicily, Italy) (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: One hundred years ago (December 1908) a devastating tsunami associated with an earthquake struck the Straits of Messina area, causing many casualties. On the basis of seismic data and observed runups and arrival times, we suggest that the tsunami was likely generated by coseismic seafloor displacement coupled with a small submarine landslide triggered by the earthquake. Backwards ray-tracing using a depth-dependent velocity field, submarine slope analysis and inferences form the main drainage network allowed us to identify possible locations for the source of the submarine landslide. We then performed direct simulations of tsunamis generated by the earthquake and landslides and identified the tsunami source (earthquake plus landslide) that best fits observational data in a small volume submarine landslide (1–5 km3) located offshore Nizza, Sicily.
    Description: Published
    Description: L16304
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: 4.6. Oceanografia operativa per la valutazione dei rischi in aree marine
    Description: JCR Journal
    Description: reserved
    Keywords: earthquake ; landslide ; tsunami ; 03. Hydrosphere::03.01. General::03.01.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
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  • 52
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    Kinematics and Source Zone Properties of the 2004 Sumatra-Andaman Earthquake and Tsunami: Nonlinear Joint Inversion of Tide-Gage, Satellite Altimetry and GPS data (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We (re)analyzed the source of the 26 December 2004 Sumatra-Andaman earthquake and tsunami through a nonlinear joint inversion of an in-homogeneous dataset made up of tide-gages, satellite altimetry, and far-field GPS recordings. The purpose is two-fold: (1) the retrieval of the main kinematics rupture parameters (slip, rake, rupture velocity); (2) the inference of the rigidity of the source zone. We independently estimate the slip from tsunami data and the seismic moment from geodetic data, so to derive the rigidity. Our results confirm that the source of the 2004 Sumatra-Andaman earthquake has a complex geometry, constituted by three main slip patches, with slip peaking at ~30 meters in the Southern part of the source. The rake direction rotates counter-clockwise at North, according to the direction of convergence along the trench. The rupture velocity is higher in the deeper than in the shallower part of the source, consistently with the expected increase of rigidity with depth. It is also lower in the Northern part, consistently with known variations of the incoming plate properties and shear velocity. Our model features a rigidity (20-30 GPa), that is lower than PREM average for the seismogenic volume [Dziewonski and Anderson, 1981]. The source rigidity is one of the factors controlling the tsunamigenesis: for a given seismic moment, the lower the rigidity, the higher the induced seafloor displacement. The general consistence between our source model and previous studies supports the effectiveness of our approach to the joint inversion of geodetic and tsunami data for the rigidity estimation.
    Description: In press
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: Source process ; Sumatra ; Tsunami ; joint inversion ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
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  • 53
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    Temporal changes in seismic wave propagation towards the end of the 2002 Mt Etna eruption (2010)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: Stress can undergo rapid temporal changes in volcanic environments, and this is particularly true during eruptions. We use two independent methods, coda wave interferometry (CWI) and shear wave splitting (SWS) analysis to track stress related wave propagation effects during the waning phase of the 2002 NE fissure eruption at Mt Etna. CWI is used to estimate temporal changes in seismic wave velocity, while SWS is employed to monitor changes in elastic anisotropy. We analyse seismic doublets, detecting temporal changes both in wave velocities and anisotropy, consistent with observed eruptive activity. In particular, syn-eruptive wave propagation changes indicate a depressurization of the system, heralding the termination of the eruption, which occurs three days later.
    Description: Published
    Description: 1779-1788
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Interferometry ; Seismic anisotropy ; Volcano seismology ; Volcano monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 54
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    Laboratory measurements of the frictional properties of the Zuccale 3 low-angle normal fault, Elba Island, Italy (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Using a case study from the island of Elba, Italy, we seek to test the hypothesis that 7 the presence of minerals with low frictional strengths can explain prolonged slip on 8 low-angle normal faults. The central core of the Zuccale low-angle normal fault 9 contains a distinctive fault rock zonation that developed during progressive exhumation. 10 Most fault rock components preserve microstructural evidence for having accommodated 11 deformation entirely, or partly, by frictional mechanisms. One millimeter thick sample 12 powders of all the major fault rock components were deformed in a triaxial deformation 13 apparatus under water-saturated conditions, at room temperature, and at constant effective 14 normal stresses of 25, 50, and 75 MPa. Pore fluid pressure was maintained at 50 MPa 15 throughout. Overall, the coefficient of friction (m) of the fault rocks varies between 16 0.25 and 0.8, emphasizing the marked strength heterogeneity that may exist within 17 natural fault zones. Also, m is strongly dependent on fault rock mineralogy and is 18 〈0.45 for fault rocks containing talc, chlorite, and kaolinite and 〉0.6 for fault rocks 19 dominated by quartz, dolomite, calcite, and amphibole. Localization of frictional slip 20 within talc-rich portions of the fault core can potentially explain movements along the 21 Zuccale fault over a wide range of depths within the upper crust, although the 22 mechanical importance of the talc-bearing fault rocks likely decreased following their 23 dismemberment into a series of poorly connected fault rock lenses. Additionally, slip 24 within clay-bearing fault gouges with m between 0.4 and 0.5 may have facilitated 25 movements in the uppermost (〈2 km) crust. For several other fault rock components, 26 m varies between 0.5 and 0.8, and mineralogical weakening alone is insufficient to 27 account for low-angle slip. In the latter fault rock components, other weakening 28 mechanisms such as the development of high fluid pressures, or dissolution-precipitation 29 creep, may have been particularly important in reducing fault strength.
    Description: In press
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Friction ; Low-Angle Normal Faults ; Experiments ; Weakening ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 55
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    On the transient behavior of frictional melt during seismic slip (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: In a recent work on the problem of sliding surfaces under the presence of frictional melt (applying in particular to earthquake fault dynamics), we derived from first principles an expression for the steady state friction compatible with experimental observations. Building on the expressions of heat and mass balance obtained in the above study for this particular case of Stefan problem (phase transition with a migrating boundary) we propose here an extension providing the full time-dependent solution (including the weakening transient after pervasive melting has started, the effect of eventual steps in velocity and the final decelerating phase). A system of coupled equations is derived and solved numerically. The resulting transient friction and wear evolution yield a satisfactory fit (1) with experiments performed under variable sliding velocities (0.9-2 m/s) and different normal stresses (0.5-20 MPa) for various rock types and (2) with estimates of slip weakening obtained from observations on ancient seismogenic faults that host pseudotachylite (solidified melt). The model allows to extrapolate the experimentally observed frictional behavior to large normal stresses representative of the seismogenic Earth crust (up to 200 MPa), high slip rates (up to 9 m/s) and cases where melt extrusion is negligible. Though weakening distance and peak stress vary widely, the net breakdown energy appears to be essentially independent of either slip velocity and normal stress. In addition, the response to earthquake-like slip can be simulated, showing a rapid friction recovery when slip rate drops. We discuss the properties of energy dissipation, transient duration, velocity weakening, restrengthening in the decelerating final slip phase and the implications for earthquake source dynamics.
    Description: S.N. and G.D.T. were supported by a European Research Council Starting Grant Project (acronym USEMS) and by a Progetti di Eccellenza Fondazione Cassa di Risparmio di Padova e Rovigo. We are grateful to Nick Beeler (and to an anonymous referee) for their constructive reviews and their help to improve the clarity of the manuscript.
    Description: Published
    Description: B10301
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: Friction ; Melt ; Earthquake dynamics ; fault mechanics ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
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  • 56
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    Energy radiation from intermediate to large magnitude earthquakes: implications for dynamic fault weakening (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: The amount of energy radiated from an earthquake can be measured using recent methods based on earthquake coda signals and spectral ratios. Such methods are not altered by either site or directivity effects, with the advantage of a greatly improved accuracy. Several studies of earthquake sequences based on the above measurements showed evidence of a breakdown in self-similarity in the moment to energy relation. Radiated energy can be also used as a gauge to estimate the average dynamic stress drop on the fault. Here we compute the dynamic stress drop, infer the co-seismic friction and estimate the co-seismic heating resulting from the frictional work during events from different main shock-aftershock earthquake sequences. We relate the dynamic friction to the maximum temperature rise estimated on the faults for each earthquake. Our results are strongly indicative that a thermally triggered dynamic frictional weakening is present, responsible for the breakdown in self-similarity. These observations from seismic data are compatible with recent laboratory evidence of thermal weakening in rock friction under seismic slip-rates, associated to various physical processes such as melting, decarbonation or dehydration.
    Description: Kevin Mayeda was supported under Weston Geophysical subcontract No. GC19762NGD and AFRL contract No. FA8718-06-C-0024. Work by L. Malagnini was performed under the auspices of the Dipartimento della Protezione Civile, under contract S3 – INGV-DPC (2007-2009), project: “Valutazione rapida dei parametri e degli effetti dei forti terremoti in Italia e nel Mediterraneo”.
    Description: Published
    Description: B06319
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: earthquake radiation ; coda ; friction ; self-similarity ; dynamic weakening ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
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  • 57
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    On claimed ULF seismogenic fractal signatures in the geomagnetic field (2010)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: During the last ten years, fractal analysis of ultra-low-frequency (ULF) geomagnetic field components has been proposed as one of the most promising tools to highlight magnetic precursor signals possibly generated by the preparation processes of earthquakes. Several papers claim seismogenic changes in the fractal features of the geomagnetic field some months before earthquakes occur. The target of the present paper is to put forth a qualitative investigation on the fractal characteristics of ULF magnetic signatures that previous authors have claimed to be related without doubt to strong earthquakes. This analysis takes into account both the temporal evolution of the geomagnetic field fractal parameters reported in previous researches and the temporal evolution of global geomagnetic activity. Running averages of the geomagnetic indices ΣKp and Ap are plotted into the original figures from the previous publications. This simple analysis shows that the fractal features of the ULF geomagnetic field are closely related to the geomagnetic activity both before and after the earthquake occurs. The correlation between the geomagnetic field fractal parameters and geomagnetic activity is clearly shown over both long and short time scales. In light of this, the present paper shows that fractal behaviors of previously claimed seismogenic ULF magnetic signatures depend mainly on geomagnetic activity due to solar-terrestrial interaction. Therefore, previously reported association with the preparation process of the earthquake is dubious.
    Description: Published
    Description: A10236
    Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake precursors ; Geomagnetic field ; ULF ; Fractal analysis ; SOC ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.05. Geomagnetism::04.05.05. Main geomagnetic field ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques
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  • 58
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    Water vapor sounding with the far infrared REFIR-PAD spectroradiometer from a high-altitude ground-based station during the ECOWAR campaign (2011)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: The Radiation Explorer in the Far InfraRed-Prototype for Applications and Development (REFIR-PAD) spectroradiometer was operated from the Testa Grigia Italian-Alps station in March 2007 during the Earth Cooling by Water Vapour Radiation (ECOWAR) measurement campaign, obtaining downwelling radiance spectra in the 100–1100 cm−1 range, under clear-sky conditions and in the presence of cirrus clouds. The analysis of these measurements has proven that the instrument is capable of determining precipitable water vapor with a total uncertainty of 5–7% by using the far-infrared rotational band of water. The measurement is unaffected by the presence of cirri, whose optical depth can be instead retrieved as an additional parameter. Information on the vertical profiles of water vapor volume mixing ratio and temperature can also be retrieved for three altitude levels. The ability to measure the water vapor column with a simple, uncooled instrument, capable of operating continuously and with a time resolution of about 10 min, makes REFIR-PAD a very valuable instrument for meteorological and climatological studies for the characterization of the water vapor distribution.
    Description: Published
    Description: D02310
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: reserved
    Keywords: tropospheric water vapor ; IR spectroscopy ; REFIR-PAD ; ECOWAR ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques
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  • 59
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    Evolution of an active lava flow field using a multitemporal LIDAR acquisition (2010)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: Application of light detection and ranging (LIDAR) technology in volcanology has 7 developed rapidly over the past few years, being extremely useful for the generation 8 of high‐spatial‐resolution digital elevation models and for mapping eruption products. 9 However, LIDAR can also be used to yield detailed information about the dynamics of 10 lava movement, emplacement processes occuring across an active lava flow field, and the 11 volumes involved. Here we present the results of a multitemporal airborne LIDAR survey 12 flown to acquire data for an active flow field separated by time intervals ranging from 13 15 min to 25 h. Overflights were carried out over 2 d during the 2006 eruption of Mt. Etna, 14 Italy, coincident with lava emission from three ephemeral vent zones to feed lava flow in 15 six channels. In total 53 LIDAR images were collected, allowing us to track the volumetric 16 evolution of the entire flow field with temporal resolutions as low as ∼15 min and at a 17 spatial resolution of 〈1 m. This, together with accurate correction for systematic errors, 18 finely tuned DEM‐to‐DEM coregistration and an accurate residual error assessment, 19 permitted the quantification of the volumetric changes occuring across the flow field. We 20 record a characteristic flow emplacement mode, whereby flow front advance and channel 21 construction is fed by a series of volume pulses from the master vent. Volume pulses 22 have a characteristic morphology represented by a wave that moves down the channel 23 modifying existing channel‐levee constructs across the proximal‐medial zone and building 24 new ones in the distal zone. Our high‐resolution multitemporal LIDAR‐derived DEMs 25 allow calculation of the time‐averaged discharge rates associated with such a pulsed flow 26 emplacement regime, with errors under 1% for daily averaged values.
    Description: This work was partially funded by the Italian 930 Dipartimento della Protezione Civile in the frame of the 2007–2009 Agree- 931 ment with Istituto Nazionale di Geofisica e Vulcanologia–INGV. A.F. 932 benefited from the MIUR‐FIRB project “Piattaforma di ricerca multi‐disci- 933 plinare su terremoti e vulcani (AIRPLANE)” n. RBPR05B2ZJ. S.T. 934 benefited from the project FIRB “Sviluppo di nuove tecnologie per la prote- 935 zione e difesa del territorio dai rischi naturali (FUMO)” funded by the Italian 936 Ministero dell’Istruzione, dell’Università e della Ricerca.
    Description: Published
    Description: B11203
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: LIDAR ; lava flow ; Etna ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 60
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    A completeness analysis of the national seismic network of Italy (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Accepted for publication in Journal of Geophysical Research. Copyright (2009) American Geophysical Union. Further reproduction or electronic distribution is not permitted.
    Description: We present the first detailed study of earthquake detection capabilities of the Italian National Seismic Network and of the completeness threshold of its earthquake catalog. The network in its present form started operating on 16 April 2005 and is a significant improvement over the previous networks. For our analysis, we employed the PMC method as introduced by Schorlemmer and Woessner (2008). This method does not estimate completeness from earthquakes samples as traditional methods, mostly based on the linearity of earthquake-size distributions. It derives detection capabilities for each station of the network and synthesizes them into maps of detection probabilities for earthquakes of a given magnitude. Thus, this method avoids the many assumptions about earthquake distributions that traditional methods make. The results show that the Italian National Seismic Network is complete at $M=2.9$ for the entire territory excluding the islands of Sardinia, Pantelleria, and Lampedusa. At the $M=2.5$ level, which is the reporting threshold level of the Italian Civil Protection, the network may miss events in southern parts of Apulia and the western part of Sicily. The stations are connected through many different telemetry links to the operational datacenter in Rome. Scenario computations show that no significant drop in completeness occurs if one of the three major links fail, indicating a well-balanced network setup.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: Italian seismicity ; earthquake detection capability ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 61
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    Real-time forecasting following a damaging earthquake (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: An edited version of this paper was published by AGU. Copyright (2009) American Geophysical Union.
    Description: We describe the results of a prospective, real-time earthquake forecast experiment made during a seismic emergency. A $M_w$ 6.3 earthquake struck the city of L'Aquila, Italy on April 6, 2009, causing hundreds of deaths and vast damage. Immediately following this event, we began producing daily earthquake forecasts for the region, and we provided these forecasts to Civil Protection -- the agency responsible for managing the emergency. The forecasts are based on a stochastic model that combines the Gutenberg-Richter distribution of earthquake magnitudes and power-law decay in space and time of triggered earthquakes. The results from the first month following the L'Aquila earthquake exhibit a good fit between forecasts and observations, indicating that accurate earthquake forecasting is now a realistic goal. Our experience with this experiment demonstrates an urgent need for a connection between probabilistic forecasts and decision-making in order to establish -- before crises -- quantitative and transparent protocols for decision support.
    Description: Published
    Description: L21302
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: partially_open
    Keywords: earthquake forecast ; L'Aquila earthquake ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability
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  • 62
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    Topographic control on lava flow paths at Mount Etna, Italy: Implications for hazard assessment (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Assessment of the hazard from lava flow inundation at the active volcano of Mount Etna, Italy, was performed by calculating the probability of lava flow inundation at each position on the volcano. A probability distribution for the formation of new vents was calculated using geological and volcanological data from past eruptions. The simulated lava flows from these vents were emplaced using a maximum expected flow length derived from geological data on previous lava flows. Simulations were run using DOWNFLOW, a digital-elevation-model-based model designed to predict lava flow paths. Different eruptive scenarios were simulated by varying the elevation and probability distribution of eruptive points. Inundation maps show that the city of Catania and the coastal zone may only be impacted by flows erupted from low-altitude vents (〈1500 m elevation) and that flank eruptions at elevations 〉2000 m preferentially inundate the northeast and southern sectors of the volcano as well as the Valle del Bove. Eruptions occurring in the summit area (〉3000 m elevation) pose no threat to the local population. Discrepancies between the results of simple, hydrological models and those of the DOWNFLOW model show that hydrological approaches are inappropriate when dealing with Etnean lava flows. Because hydrological approaches are not designed to reproduce the full complexity of lava flow spreading, they underestimate the catchment basins when the fluid has a complex rheology.
    Description: Published
    Description: F01019
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic hazard ; lava flow ; Mount Etna ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 63
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    Predicting the impact of lava flows at Mount Etna, Italy (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Forecasting the time, nature, and impact of future eruptions is difficult at volcanoes such as Mount Etna, in Italy, where eruptions occur from the summit and on the flanks, affecting areas distant from each other. Nonetheless, the identification and quantification of areas at risk from new eruptions are fundamental for mitigating potential human casualties and material damage. Here, we present new results from the application of a methodology to define flexible high‐resolution lava invasion susceptibility maps based on a reliable computational model for simulating lava flows at Etna and on a validation procedure for assessing the correctness of susceptibility mapping in the study area. Furthermore, specific scenarios can be extracted at any time from the simulation database, for land use and civil defense planning in the long term, to quantify, in real time, the impact of an imminent eruption, and to assess the efficiency of protective measures.
    Description: This work was sponsored by the Italian Ministry for Education, University and Research, FIRB project RBAU01RMZ4 “Lava flow simulations by Cellular Automata,” and by the National Civil Defense Department and INGV (National Institute of Geophysics and Volcanology), project V3_6/09 “V3_6 – Etna.”
    Description: Published
    Description: B04203
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: lava flows ; volcanic hazard ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 64
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    Slip Distribution of the 2003 Tokachi-oki Mw 8.1 earthquake from joint inversion of tsunami waveforms and geodetic data (2011)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: We study the 2003 Mw 8.1 Tokachi‐oki earthquake, a great interplate event that occurred along the southwestern Kuril Trench and generated a significant tsunami. To determine the earthquake slip distribution, we perform the first joint inversion of tsunami waveforms measured by tide gauges and of coseismic displacement measured both by GPS stations and three ocean bottom pressure gauges (PG) for this event. The resolution of the different data sets on the slip distribution is assessed by means of several checkerboard tests. Results show that tsunami data constrain the slip distribution offshore, whereas GPS data constrain the slip distribution in the onshore zone. The three PG data only coarsely constrain the offshore slip, indicating that denser networks should be installed close to subduction zones. Combining the three data sets significantly improves the inversion results. Joint inversion of the 2003 Tokachi‐oki earthquake data leads to maximum slip values (∼6 m) confined at depths greater than ∼25 km, between 30 and 80 km northwest of the hypocenter, with a patch of slip (3 m) in the deepest part of the source (∼50 km depth). Slip values are very low (≤1 m) updip from the hypocenter. Furthermore, the rupture does not extend on the plate interface off Akkeshi. As a significant back slip amount (∼4 m) has accumulated there since the last 1952 earthquake, this segment could rupture during the next large interplate event along the Kuril Trench.
    Description: Published
    Description: B11313
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: tsunami ; coseismic displacement ; joint inversion ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
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  • 65
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    A relation between lava discharge rate, thermal insulation, and flow area set using lidar data (2011)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: A simple linear relation can be used to link time averaged discharge rate (TADR) and lava flow area (A). The relation applies to given insulation conditions, as described by the characteristic flow surface temperature (Te), and will vary from case-to-case depending on rheological and topographic influences on flow spreading. Most flows have insulation conditions that change through time, modifying the relationship between TADR and area as insulation conditions evolve. Using lidar data we can define TADR, the flow area that the discharge feeds and Te, allowing generation of a case-specific relation to convert satellite-data-derived flow areas to TADR. For Etna's 2006 lava flow field we obtain a relation whereby TADR = 5.6 × 10−6 A for well insulated conditions (Te = 100°C) and TADR = 1.5 × 10−4 A for poorly insulated conditions (Te = 600°C).
    Description: Published
    Description: L20308
    Description: 1.10. TTC - Telerilevamento
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: lava flow ; discharge rate ; area ; surface temperature ; lidar ; Etna. ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 66
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    Magnetic properties of sedimentary greigite (Fe3S4): an update (2011)
    American Geophysical Union
    Details
    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
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  • 67
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    Principles of volcanic risk metrics: theory and the case study of Mt. Vesuvius and Campi Flegrei (Italy) (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: An edited version of this paper was published by AGU. Copyright (2009) American Geophysical Union.
    Description: Despite volcanic risk having been defined quantitatively more than 30 years ago, this risk has been managed without being effectively measured. The recent substantial progress in quantifying eruption probability paves the way for a new era of rational science-based volcano risk management, based on what may be termed ‘‘volcanic risk metrics’’ (VRM). In this paper, we propose the basic principles of VRM, based on coupling probabilistic volcanic hazard assessment and eruption forecasting with cost-benefit analysis. The VRM strategy has the potential to rationalize decision making across a broad spectrum of volcanological questions. When should the call for evacuation be made? What early preparations should be made for a volcano crisis? Is it worthwhile waiting longer? What areas should be covered by an emergency plan? During unrest, what areas of a large volcanic field or caldera should be evacuated, and when? The VRM strategy has the paramount advantage of providing a set of quantitative and transparent rules that can be established well in advance of a crisis, optimizing and clarifying decision-making procedures. It enables volcanologists to apply all their scientific knowledge and observational information to assist authorities in quantifying the positive and negative risk implications of any decision.
    Description: Published
    Description: B03213
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: risk assessment ; decision making ; campi flegrei ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 68
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    Subaqueous density flow processes and deposits of an island volcano landslide (Stromboli Island, Italy) (2010)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: Stromboli is a 3000 m high island volcano, rising to 900 m above sea-level. It is the most active volcano of the Aeolian Archipelago in the Tyrrhenian Sea (Italy). Major, large volume (1 km3) sector collapses, four occurring in the last 13 kyr, have played an important role in shaping the north-western flank (Sciara del Fuoco) of the volcano, potentially generating a high-risk tsunami hazard for the Aeolian Islands and the Italian coast. However, smaller volume, partial collapses of the Sciara del Fuoco have been shown to be more frequent tsunami-generating events. One such event occurred on 30 December 2002, when a partial collapse of the north-western flank of the island took place. The resulting landslide generated 10 m high tsunami waves that impacted the island. Multibeam bathymetry, side-scan sonar imaging and visual observations reveal that the landslide deposited 25 to 30 × 106 m3 of sediment on the submerged slope offshore from the Sciara del Fuoco. Two contiguous main deposit facies are recognized: (i) a chaotic, coarse-grained (metre-sized to centimetre-sized clasts) deposit; and (ii) a sand deposit containing a lower, cross-bedded sand layer and an upper structureless pebbly sand bed capped by sea floor ripple bedforms. The sand facies develops adjacent to and partially overlying the coarse deposits. Characteristics of the deposits suggest that they were derived from cohesionless, sandy matrix density flows. Flow rheology and dynamics led to the segregation of the density flow into sand-rich and clast-rich regions. A range of density flow transitions, both in space and in time, caused principally by particle concentration and grain-size partitioning within cohesionless parent flows was identified in the deposits of this relatively small-scale submarine landslide event.
    Description: Published
    Description: 1488-1504
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Flow transitions ; island volcano ; subaqueous cohesionless density flows ; submarine landslide deposits ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 69
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    Vesiculation in magmas from Stromboli and implications for normal Strombolian activity and paroxysmal explosions in basaltic systems (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We performed a series of X-ray tomographic experiments and lattice Boltzmann permeability simulations on pyroclastic products from explosive activity at Stromboli between December 2004 and May 2006. We reconstructed the 3-D textures of vesicles to investigate the relationship between the nature of vesiculation in the erupted products and the dynamics of gas transport in the shallow conduit in order to derive implications for the eruptive behavior of basaltic volcanoes. Scoriae from normal Strombolian explosions display remarkably consistent vesicle volume distributions fit by power laws with an exponent of 1 (±0.2). We ascribe the origin of such distributions to the combined effect of coalescence and continuous nucleation events in the steady state, shallow magma system that supplies normal Strombolian activity. Volume distributions and textures of vesicles in pumice clasts from the 5 April 2003 and 15 March 2007 paroxysmal activity are markedly different from those in the scoriae. Besides a power law function with a higher exponent, portions of these distributions can be also fit by an exponential function, suggesting the attempt of the system to reach near-equilibrium conditions. The investigated pumice clasts also lack the large, connecting vesicles responsible for the development of degassing pathways in the Stromboli magma that erupts the scoriae. This testifies to a decreased degassing efficiency of the magma associated with paroxysmal explosions and potential overpressure buildup at depth. By comparison with degassing experiments on basaltic melts, we derive a time constraint on the order of minutes to hours for the incubation of paroxysms at Stromboli.
    Description: Published
    Description: B01206
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: basaltic explosions ; vesicle textures ; third dimension ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 70
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    The contribution of synchrotron X-ray computed microtomography to understanding volcanic processes (2010)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: A series of computer microtomography experiments are reported which were performed by using a third-generation synchrotron radiation source on volcanic rocks from various active hazardous volcanoes in Italy and other volcanic areas in the world. The applied technique allowed the internal structure of the investigated material to be accurately imaged at the micrometer scale and three-dimensional views of the investigated samples to be produced as well as three-dimensional quantitative measurements of textural features. Thegeometryof thevesicle (gas-filledvoid) network in volcanic products of both basaltic and trachytic compositions were particularly focused on, as vesicle textures are directly linked to the dynamics of volcano degassing. This investigation provided novel insights into modes of gas exsolution, transport and loss in magmas that were not recognized in previous studies using solely conventional two- dimensional imaging techniques. The results of this study are important to understanding the behaviour of volcanoes and can be combined with other geosciences disciplines to forecast their future activity.
    Description: In press
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: high-resolution three-dimensional imaging ; X-ray computed microtomography ; volcanic eruptions ; volcanic rock textures ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 71
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    Long term variations of the Campi Flegrei (Italy) volcanic system as revealed by the monitoring of hydrothermal activity (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Long duration time-series of the chemical composition of fumaroles and of soil CO2 flux reveal that important variations in the activity of the Solfatara fumarolic field, the most important hydrothermal site of Campi Flegrei, occurred in the 2000-2008 period. A continuous increase of the CO2 concentrations, and a general decrease of the CH4 concentrations are interpreted as the consequence of the increment of the relative amount of magmatic fluids, rich in CO2 and poor in CH4, hosted by the hydrothermal system. Contemporaneously, the H2O-CO2-He-N2 gas system shows remarkable compositional variations in the samples collected after July 2000 with respect to the previous ones, indicating the progressive arrival at the surface of a magmatic component different from that involved in the 1983-84 episode of volcanic unrest (1983-1984 bradyseism). The change starts in 2000 concurrently with the occurrence of relatively deep, long-period seismic events which were the indicator of the opening of an easy-ascent pathway for the transfer of magmatic fluids towards the shallower, brittle domain hosting the hydrothermal system. Since 2000, this magmatic gas source is active and causes ground deformations, seismicity as well as the expansion of the area affected by soil degassing of deeply derived CO2. Even though the activity will most probably be limited to the expulsion of large amounts of gases and thermal energy, as observed in other volcanoes and in the past activity of Campi Flegrei, the behavior of the system in the future is, at the moment, unpredictable.
    Description: Published
    Description: B03205
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: Campi Flegrei ; CO2 ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 72
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    Mwpd: A Duration-Amplitude Procedure for Rapid Determination of Earthquake Magnitude and Tsunamigenic Potential from P Waveforms (2010)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: We present a duration-amplitude procedure for rapid determination of a moment magnitude, Mwpd, for large earthquakes using P-wave recordings at teleseismic distances. Mwpd can be obtained within 20 minutes or less after the event origin time as the required data is currently available in near-real time. The procedure determines apparent source durations, T0, from high-frequency, P-wave records, and estimates moments through integration of broadband displacement waveforms over the interval tP to tP+T0, where tP is the P arrival time. We apply the duration-amplitude methodology to 79 recent, large earthquakes (Global Centroid- Moment Tensor magnitude, MwCMT, 6.6 to 9.3) with diverse source types. The results show that a scaling of the moment estimates for interplate thrust and possibly tsunami earthquakes is necessary to best match MwCMT. With this scaling, Mwpd matches MwCMT typically within ±0.2 magnitude units, with a standard deviation of σ=0.11, equaling or outperforming other approaches to rapid magnitude determination. Furthermore, Mwpd does not exhibit saturation; that is, for the largest events, Mwpd does not systematically underestimate MwCMT. The obtained durations and duration-amplitude moments allow rapid estimation of an energy-to-moment parameter Θ* used for identification of tsunami earthquakes. Our results show that Θ* ≤ -5.7 is an appropriate cutoff for this identification, but also show that neither Θ* nor Mw is a good indicator for tsunamigenic events in general. For these events we find that a reliable indicator is simply that the duration T0 is greater than about 50 sec. The explicit use of the source duration for integration of displacement seismograms, the moment scaling, and other characteristics of the duration-amplitude methodology make it an extension of the widely used, Mwp, rapid-magnitude procedure. The need for a moment scaling for interplate thrust and possibly tsunami earthquakes may have important implications for the source physics of these events.
    Description: DPC-INGV (2007-2009) S3 Project
    Description: Published
    Description: 200-214
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: earthquakes, Richter magnitude, seismic moment, seismograms, tsunami,  earthquake­source mechanism ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
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  • 73
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    A new velocity field for Greece: Implications for the kinematics and dynamics of the Aegean (2010)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Description: A new set of geodetic velocities for Greece and the Aegean, derived from 254 survey-mode and continuous GPS sites, is used to test kinematic and dynamic models for this area of rapid continental deformation. Modeling the kinematics of the Aegean by the rotation of a small number (3–6) of blocks produces RMS misfits of ~5 mm yr−1 in the southern Aegean and western Peloponnese, indicating significant internal strain within these postulated blocks. It is possible to fit the observed velocities to within 2–3 mm yr−1 (RMS) by models that contain 10 or more blocks, but many such models can be found, with widely varying arrangements of blocks, that fit the data equally well provided that the horizontal dimension of those blocks is not larger than 100–200 km. A continuous field of velocity calculated from the GPS velocities by assuming that strain rates are homogeneous on the scale of ~120 km fits the observed velocities to better than 2–3 mm yr−1 (RMS), with systematic misfits, representing more localized strain, confined to a region approximately 100 × 100 km in size around the western Gulf of Corinth. This velocity field accounts for the major active tectonic features of Greece and the Aegean, including the widespread north-south extensional deformation and the distributed strike-slip deformation in the NE Aegean and western Greece. The T axes of earthquakes are aligned with the principal axes of elongation in the geodetic field, major active normal fault systems are perpendicular to those axes, and ~90% of the large earthquakes in this region during the past 120 years took place within the areas in which the geodetic strain rate exceeds 30 nanostrain yr−1. These observations suggest that the faulting within the upper crust of the Aegean region is driven by forces that are coherent over a scale that is significantly greater than 100 km. It is likely that those forces arise primarily from differences in gravitational potential energy within the lithosphere of the region.
    Description: Published
    Description: B10403
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: GPS ; Greece ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous
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  • 74
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    Patterns in the recent 2007–2008 activity of Mount Etna volcano investigated by integrated geophysical and geochemical observations (2010)
    American Geophysical Union
    Details
    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
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  • 75
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    Response of Mount Etna to dynamic stresses from distant earthquakes (2010)
    American Geophysical Union
    Details
    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
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  • 76
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    Anatomy of an unstable volcano from InSAR: Multiple processes affecting flank instability at Mt. Etna, 1994–2008 (2010)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Description: Volcano deformation may occur under different conditions. To understand how a volcano deforms, as well as relations with magmatic activity, we studied Mt. Etna in detail using interferometric synthetic aperture radar (InSAR) data from 1994 to 2008. From 1994 to 2000, the volcano inflated with a linear behavior. The inflation was accompanied by eastward and westward slip on the eastern and western flanks, respectively. The portions proximal to the summit showed higher inflation rates, whereas the distal portions showed several sectors bounded by faults, in some cases behaving as rigid blocks. From 2000 to 2003, the deformation became nonlinear, especially on the proximal eastern and western flanks, showing marked eastward and westward displacements, respectively. This behavior resulted from the deformation induced by the emplacement of feeder dikes during the 2001 and 2002–2003 eruptions. From 2003 to 2008, the deformation approached linearity again, even though the overall pattern continued to be influenced by the emplacement of the dikes from 2001 to 2002. The eastward velocity on the eastern flank showed a marked asymmetry between the faster sectors to the north and those (largely inactive) to the south. In addition, from 1994 to 2008 part of the volcano base (south, west, and north lower slopes) experienced a consistent trend of uplift on the order of ∼0.5 cm/yr. This study reveals that the flanks of Etna have undergone a complex instability resulting from three main processes. In the long term (103–104 years), the load of the volcano is responsible for the development of a peripheral bulge. In the intermediate term (≤101 years, observed from 1994 to 2000), inflation due to the accumulation of magma induces a moderate and linear uplift and outward slip of the flanks. In the short term (≤1 year, observed from 2001 to 2002), the emplacement of feeder dikes along the NE and south rifts results in a nonlinear, focused, and asymmetric deformation on the eastern and western flanks. Deformation due to flank instability is widespread at Mt. Etna, regardless of volcanic activity, and remains by far the predominant type of deformation on the volcano.
    Description: ESA provided the SAR data (Cat‐1 no. 4532 and GEO Supersite initiative). The DEM was obtained from the SRTM archive, while the ERS‐1/2 orbits are courtesy of the TU‐Delft, The Netherlands. This work was partially funded by INGV and the Italian DPC (DPCINGV project V4 “Flank”), the Italian DPC (under special agreement with IREA‐CNR), and the Italian Space Agency under contract “sistema rischio vulcanico (SRV).” The authors thank Francesco Casu, Paolo Berardino, and Riccardo Lanari for their support and Geoff Wadge and Michael Poland for their helpful and constructive review of the manuscript.
    Description: Published
    Description: B10405
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Flank instability ; InSAR ; volcanoes ; Etna ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.04. Instrumentation and techniques of general interest::05.04.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
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  • 77
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    A buried volcano in the Calabrian Arc (Italy) revealed by high‐resolution aeromagnetic data (2010)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Description: Aeromagnetic data collected between the Aeolian volcanoes (southern Tyrrhenian Sea) and the Calabrian Arc (Italy) highlight a WNW‐ESE elongated positive magnetic anomaly centered on the Capo Vaticano morphological ridge (Tyrrhenian coast of Calabria), characterized by an apical, subcircular, flat surface. Results of forward and inverse modeling of the magnetic data show a 20 km long and 3–5 km wide magnetized body that extends from sea floor to about 3 km below sea level. The magnetic properties of this body are consistent with those of the medium to highly evolved volcanic rocks of the Aeolian Arc (i.e., dacites and rhyolites). In the Calabria mainland, widespread dacitic to rhyolitic pumices with calc‐alkaline affinity of Pleistocene age (1–0.7 Ma) are exposed. The tephra falls are related to explosive activity and show a decreasing thickness from the Capo Vaticano area southeastward. The presence of lithics indicates a provenance from a source located not far from Capo Vaticano. The combined interpretation of the magnetic and available geological data reveal that (1) the Capo Vaticano WNW‐ESE elongated positive magnetic anomaly is due to the occurrence of a WNW‐ESE elongated sill; (2) such a sill represents the remnant of the plumbing system of a Pleistocene volcano that erupted explosively producing the pumice tephra exposed in Calabria; and (3) the volcanism is consistent with the Aeolian products, in terms of age, magnetic signature, and geochemical affinity of the erupted products,. The results indicate that such volcanism developed along seismically active faults transversal to the general trend of the Aeolian Arc and Calabria block, in an area where uplift is maximized (∼4 mm/yr). Such uplift could also be responsible for fragmentation of the upper crust and formation of transversal faults along which seismic activity and volcanism occur.
    Description: Published
    Description: B11101
    Description: 3.2. Tettonica attiva
    Description: 3.4. Geomagnetismo
    Description: 5.7. Consulenze in favore di istituzioni nazionali e attività nell'ambito di trattati internazionali
    Description: JCR Journal
    Description: restricted
    Keywords: aeromagnetic anomalies ; volcanic arc ; tectonics of the Calabrian Arc ; risk assessment ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs
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  • 78
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    Focal mechanisms for sub‐crustal earthquakes in the Gulf of Cadiz from a dense OBS deployment (2010)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Description: An eleven‐month deployment of 25 ocean bottom seismometers provides an unprecedented opportunity to study low‐magnitude local earthquakes in the complex transpressive plate boundary setting of the Gulf of Cadiz, known for the 1755 Lisbon earthquake and tsunami. 36 relocated earthquakes (ML 2.2 to 4.8) concentrate at 40– 60 km depth, near the base of the seismogenic layer in ∼140 Ma old oceanic mantle lithosphere, and roughly align along two perpendicular, NNE‐SSW and WNWESE striking structures. First motion focal mechanisms indicate compressive stress for the cluster close to the northern Horseshoe fault termination which trends perpendicular to plate convergence. Focal mechanisms for the second cluster near the southern termination of the Horseshoe fault indicate a strike‐slip regime, providing evidence for present‐day activity of a dextral shear zone proposed to represent the Eurasia‐Africa plate contact. We hypothesize that regional tectonics is characterized by slip partitioning.
    Description: Published
    Description: L18309
    Description: 3.1. Fisica dei terremoti
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: oceanic lithospheric mantle ; focal mechanisms ; stress tensor inversion ; Gulf of Cadiz ; ocean bottom seismometer ; 1755 Lisbon earthquake ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 79
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    Characterization of GPS time series at the Neapolitan volcanic area by statistical analysis (2011)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: The GPS time series recorded at the Neapolitan volcanic area reveals a very peculiar behavior. When a clear deformation is observed, the amplitude distribution evolves from a super‐Gaussian to a broader distribution. This behavior can be characterized by evaluating the kurtosis. Spurious periodic components were evidenced by independent component analysis and then removed by filtering the original signal. The time series for all stations was modeled with a fifth‐order polynomial fit, which represents the deformation history at that place. Indeed, when this polynomial is subtracted from the time series, the distributions again become super‐Gaussian. A simulation of the deformation time evolution was performed by superposing a Laplacian noise and a synthetic deformation history. The kurtosis of the obtained signals decreases as the superposition increases, enlightening the insurgence of the deformation. The presented approach represents a contribution aimed at adding further information to the studies about the deformation at the Neapolitan volcanic area by revealing geologically relevant data.
    Description: Published
    Description: B10416
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: GPS time series ; Neapolitan volcanic ; statistical analysis ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
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  • 80
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    Predicting the impact of lava flows at Mount Etna (Italy) (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Forecasting the time, nature and impact of future eruptions is difficult at volcanoes such as Mount Etna, in Italy, where eruptions occur from the summit and on the flanks, affecting areas distant from each other. Nonetheless, the identification and quantification of areas at risk from new eruptions is fundamental for mitigating potential human casualties and material damage. Here, we present new results from the application of a methodology to define flexible high-resolution lava invasion susceptibility maps based on a reliable computational model for simulating lava flows at Etna and on a validation procedure for assessing the correctness of susceptibility mapping in the study area. Furthermore, specific scenarios can be extracted at any time from the simulation database, for land-use and civil defence planning in the long-term, to quantify, in real-time, the impact of an imminent eruption, and to assess the efficiency of protective measures.
    Description: This work was sponsored by the Italian Ministry for Education, University and Research, FIRB project n° RBAU01RMZ4 “Lava flow simulations by Cellular Automata”, and by the National Civil Defence Department and INGV (National Institute of Geophysics and Volcanology), project V3_6/09 “V3_6 – Etna”.
    Description: In press
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: open
    Keywords: lava flows ; Etna ; hazard evaluation ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 81
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    Geomorphological, stratigraphic and geochronological evidence of fast Pleistocene coastal uplift in the westernmost part of the Corinth Gulf Rift (Greece) (2010)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: Rapid extension and active normal faulting in the western extremity of the Corinth Gulf are accompanied by fast coastal uplift.We investigate Pleistocene uplift west of Aigion, by attempting to date remains of marine terraces and sedimentary sequences by calcareous nannoplankton and U-series analyses. Net uplift initiated recently, due to abandonment of an older rift-bounding fault zone and increase in activity on the presently active, coastal fault zone. This change apparently coincides with an abrupt slow down (or, termination) of secondary fault block tilting within the broader hangingwall block of the older zone, indicated by an angular unconformity that dates in the early part ofMIS10 ( 390–350 ka BP, preferably, in the earlier part of this period). Net uplift driven by the coastal zone resulted in the formation of MIS9c (330 ka) and younger terraces. The formation of the unconformity and the initiation of net uplift coincide temporally with a 300–400 ka unconformity recognized by recent studies in a wide area offshore Aigion i.e. they could be part of an evolutionary event that affected the entirewestern part of the Corinth Rift or, a large area therein. Uplift rate estimates at four locations are discussed with reference to the morphotectonic context of differential uplift of secondary fault blocks, and the context of possible increase in uplift ratewith time. Themost reliable and most useful estimate for uplift rate at the longitude of the studied transect is 1.74–1.85mm/year (time-averaged estimate for the last 240 ka, based on calcareous nannoplankton and sequence-stratigraphic interpretation)
    Description: ‘3HAZ Corinth’ E.U. research project 004043 (GOCE)-3HAZ-Corinth
    Description: Published
    Description: 78 - 104
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: partially_open
    Keywords: coastal uplift ; marine terraces ; marine sequences ; deformation rate ; Pleistocene ; Corinth Gulf Reef ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology
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  • 82
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    Submarine Hydrothermal Activity on the Aeolian Arc: New evidence from Helium Isotopes (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: In November 2007 we conducted a water-column and seafloor mapping study of the submarine volcanoes of the Aeolian Arc in the southern Tyrrhenian Sea aboard the R/V Urania. A total of 26 CTD casts were completed, 13 vertical casts and 13 tows. In addition to in situ measurements of temperature, conductivity, pressure and suspended particles, we also collected discrete samples for helium isotopes, methane, and trace metals. The helium isotope ratio, which is known to be an unambiguous indicator of hydrothermal input, showed a clear excess above background at 5 out of the 10 submarine volcanoes surveyed. We found the strongest helium anomaly over Marsili seamount, where the 3He/4He ratio reached maximum values of 3He = 23% at 610 m depth compared with background values of ~ 7%. We also found smaller but distinct 3He anomalies over Enerato, Eolo, Palinuro, and Secca del Capo. We interpret these results as indicating the presence of hydrothermal activity on these 5 seamounts. Hydrothermal venting has been documented at subsea vents offshore of the islands of Panarea, Stromboli, and Vulcano (Dando et al., 1999; Di Roberto et al., 2008), and hydrothermal deposits have been sampled on many of the submarine volcanoes of the Aeolian Arc (Dekov and Savelli, 2004). However, as far as we know this is the first evidence of present day hydrothermal activity on Marsili, Enerato, and Eolo. Samples collected over Filicudi, Glabro, Lamentini, Sisifo, and Alcioni had 3He very close to the regional background values, suggesting either absence of or very weak hydrothermal activity on these seamounts. Helium isotope measurements from the background hydrocasts positioned between the volcanoes revealed the presence of an excess in 3He throughout the SE Tyrrhenian Sea. These background profiles reach a consistent maximum of about 3He = 11% at 2300 m depth. Historical helium profiles collected in the central and northern Tyrrhenian Sea in 1987 and 1997 do not show this deep 3He maximum (W. Roether and B. Klein, private comm.). Furthermore, the maximum is too deep to be attributed to the volcanoes of the Aeolian Arc, which are active at 〈1000 m depth. We are currently conducting additional measurements to determine whether this deep 3He maximum is from a local hydrothermal source or is somehow related to the deep water mass transient which occurred in the eastern Mediterranean in the 1990’s.
    Description: American Geophysical Union
    Description: Published
    Description: San Francisco
    Description: 4.6. Oceanografia operativa per la valutazione dei rischi in aree marine
    Description: open
    Keywords: submarine ; hydrothermalism ; helium isotopes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 83
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    Long term variations at Campi Flegrei (Italy) volcanic system highlighted by the monitoring of hydrothermal activity (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Long duration time-series of the chemical composition of fumaroles and of soil CO2 flux reveal that important variations in the activity of the Solfatara fumarolic field, the most important hydrothermal site of Campi Flegrei, occurred in the 2000-2008 period. A continuous increase of the CO2 concentrations, and a general decrease of the CH4 concentrations are interpreted as the consequence of the increment of the relative amount of magmatic fluids, rich in CO2 and poor in CH4, hosted by the hydrothermal system. Contemporaneously, the H2O-CO2-He-N2 gas system shows remarkable compositional variations in the samples collected after July 2000 with respect to the previous ones, indicating the progressive arrival at the surface of a magmatic componentdifferent from that involved in the 1983-84 episode of volcanic unrest (1983-1984 bradyseism). The change starts in 2000 concurrently with the occurrence of relatively deep, long-period seismic events which were the indicator of the opening of an easy-ascent pathway for the transfer of magmatic fluids towards the shallower, brittle domain hosting the hydrothermal system. Since 2000, this magmatic gas source is active and causes ground deformations, seismicity as well as the expansion of the area affected by soil degassing of deeply derived CO2. Even though the activity will most probably be limited to the expulsion of large amounts of gases and thermal energy, as observed in other volcanoes and in the past activity of Campi Flegrei, the behavior of the system in the future is, at the moment, unpredictable.
    Description: In press
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: open
    Keywords: Solfatara crater ; CO2 content ; hydrothermal system ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 84
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    Heterogeneous large total CO2 abundance in the shallow magmatic system of Kilauea volcano, Hawaii (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Due to its very low solubility in silicate melts, CO2 concentrations in melt inclusions (MIs) within crystals are commonly orders of magnitude less than the total concentration in the multiphase magma, strongly limiting the possibility to constrain CO2 abundance based on the dissolved quantities. Here we develop a statistical method to process MI data, which allows analytical uncertainties to be taken into account together with the peculiar features of the local saturation surface. The method developed leads to retrieve total H2O and CO2 concentrations in magma as well as the gas phase abundance at the time of magma crystallization. Application to a set of 29 high-resolution secondary ion mass spectrometry (SIMS) MI data from a single specimen of the 1842–1844 eruption of Kilauea, Hawaii, reveals the existence of heterogeneous total CO2 abundance, and of at least 2–6 wt % total CO2 in some magma batches, two orders of magnitude higher than the dissolved amounts and 30–50 times more abundant than the corresponding total H2O content. Heterogeneous total volatile concentrations are interpreted as due to a combination of degassing and gas flushing in magma subject to convective motion at shallow depth where P 〈 100 MPa. In such a view, the magma rising to shallow depth in the volcanic system carries initially a total volatile content ≤1 wt %, corresponding to the determined low total CO2 population, and consistent with previous global estimates. The high CO2 populations correspond to progressive CO2 enrichment due to degassing at low P and flushing from a deep CO2-rich gas. A total CO2 content 〉1 wt % is likely to characterize the 〉30 km deep magma, not represented in the analyzed inclusions, from which a CO2-rich gas phase exsolves and decouples from the liquid.
    Description: Published
    Description: B12201
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: carbon dioxide ; Kilauea volcano ; conduit dynamics ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 85
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    CO2/CH4 ratio in fumaroles a powerful tool to detect magma degassing episodes at quiescent Volcanoes (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Long time series of fumarolic compositions at Campi Flegrei (Italy), Mammoth Mountain (California), Panarea (Italy) and Nisyros (Greece) show rapid increases, up to orders of magnitude, of the CO2/CH4 ratio systematically with the occurrence of volcanic unrest periods. These easily detected anomalies originate with the arrival of CH4-poor magmatic fluids in the shallower levels of the volcanoes. The data suggest that volcanoes are characterized by magmatic activity at depth also in periods of apparent quiescence. The activity is constituted by the pulsing release of large amount of fluids which either cause unrest periods (seismicity and ground deformation) or possibly could precede volcanic eruption. This type of volcanic activity can be monitored trough the classical geophysical techniques together with the systematic sampling and analysis of fumaroles.
    Description: Published
    Description: L02302
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: CO2/CH4 ; magma degassing ; quiescent volcanoes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
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  • 86
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    Signals from the Campi Flegrei hydrothermal system: Role of a ‘‘magmatic’’ source of fluids (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: This is a parametric study that was carried out to investigate the signals generated by a hydrothermal system fed by a pulsating source of magmatic fluids. This study focuses on the effects that selected properties of the source have on the evolution of hydrothermal activity at Campi Flegrei, Italy. Numerical simulations are carried out to describe a multiphase and multicomponent hydrothermal system. Each simulation describes a short unrest phase, followed by a prolonged quiet period. During the unrest, specific properties of the fluid source (flow rate, fluid composition, source size, and unrest duration) are modified with respect to selected baseline values. The evolution of the system is tracked by looking at two parameters that can be monitored in active volcanic areas: the composition of fumarolic gases and gravity changes. The results describe the temporal evolution of these two observables and allow comparisons of the effects of different source properties. All of the simulated unrest events cause measurable changes in gas composition and gravity. For the geometry and system properties considered, these changes always last beyond the end of the unrest period, and can often persist for decades. Fluid flow rate is the source property that mostly affects the observable evolution. Gravity is more sensitive to source properties than gas composition, and it undergoes the largest and quickest changes. The results also highlight the major role that rock properties and initial conditions have in the evolution of these observable signals.
    Description: Department of Civil Protection
    Description: Published
    Description: B05201
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: hydrothermal fluids ; modeling ; monitoring ; signals ; 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::04.08.08. Volcanic risk
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  • 87
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    Intermediate-focus earthquakes under South Shetland Islands (Antarctica) (2011)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Intermediate-focus seismicity (50〈H〈100km) related to the underplating zone of the South Shetland plate have been recorded at a small aperture seismic array set up in Deception Island, Antarctica.
    Description: Published
    Description: 531-534
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Deep earthquakes ; Antarctica ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
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  • 88
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    Array tracking of the volcanic tremor source at Deception Island Antarctica (2011)
    American Geophysical Union
    Details
    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
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  • 89
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    On the mechanism of seasonal and solar cycle NmF2 variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations (2011)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Seasonal (winter/summer) and solar cycle NmF2 variations as well as summer saturation effect in NmF2 have been analyzed using Millstone Hill incoherent scatter radar (ISR) daytime observations. A self‐consistent approach to the Ne(h) modeling has been applied to extract from ISR observations a consistent set of main aeronomic parameters and to estimate their quantitative contribution to the observed NmF2 variations. The retrieved aeronomic parameters are independent of uncertainties in thermosphere and solar EUV empirical models, and this is a distinguishing feature of the present consideration. Different temperatures in winter and in summer in the course of solar cycle overlapped on the O++N2 reaction rate coefficient temperature dependence result in different NmF2 dependences on solar activity: a steep practically linear increase with a tendency to turn up in January (contrary to international reference ionosphere prediction) and a slow increase with a tendency to saturate at high solar activity in July despite increasing solar EUV irradiation. In winter the EUV flux and thermospheric parameters provide approximately equal contributions to the NmF2 increase, while in summer the contribution of thermospheric parameters is small. Both in winter and in summer the variations of atomic oxygen [O] are small at the F2 layer peak, and its contribution is small compared to linear loss coefficient, b. It is shown that the summer saturation effect in NmF2 under high solar activity is not just reduced to O/N2 or EUV flux solar cycle variations but is determined by b via the g1 temperature dependence. A new mechanism (qualitative) to explain the December anomaly in NmF2 is proposed. It is based on the idea that the areas of atomic oxygen production and its loss are spatially separated and that time is required to transfer [O] from one area to the other where [O] associates in a three‐body collision. Therefore, under a 7% increase in the O2 dissociation rate due to the Sun‐Earth distance decrease in December–January compared to June–July, an accumulation of atomic oxygen should take place in the thermosphere in the vicinity of the December solstice resulting in a 21% NmF2 increase, which is close to the observed global December effect.
    Description: Published
    Description: A03319
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: restricted
    Keywords: mid-latitude ionosphere ; thermosphere composition and chemistry ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 01. Atmosphere::01.02. Ionosphere::01.02.01. Ion chemistry and composition ; 01. Atmosphere::01.02. Ionosphere::01.02.02. Dynamics
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  • 90
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    An information theory approach to the storm‐substorm relationship (2011)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: One of the most interesting aspects of the global magnetospheric response to solar wind changes is the relationship between storms and substorms. Here we present new results on the relationship between these two different classes of magnetospheric phenomena by approaching the problem on the side of information theory. Using the Auroral Electrojet AL and SYM‐H indices as representative proxies of magnetic substorms and storms, we investigate the transfer of information by means of transfer entropy analysis (Schreiber, 2000). The obtained results seem, on average, to indicate the presence of a net transfer of information from AL to SYM‐H on time scales shorter than 10 h. On the basis of this result, geomagnetic substorms may act as a driver for the occurrence of geomagnetic storms. However, carrying out a more careful analysis which takes into account the global geomagnetic daily activity, we suggest that the direction of information flow between substorms and storms depends on the global activity level. Indeed, if it is true that a sequence of magnetospheric substorms may drive a moderate storm, it is also true that very large storms may dominate and drive the occurrence of magnetospheric substorms.
    Description: Published
    Description: A08225
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: restricted
    Keywords: Storm-substorm relationship ; Information theory ; 01. Atmosphere::01.03. Magnetosphere::01.03.02. Magnetic storms ; 01. Atmosphere::01.03. Magnetosphere::01.03.03. Magnetospheric physics ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
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  • 91
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    Evidence for the contemporary magmatic system beneath Long Valley Caldera from local earthquake tomography and receiver function analysis (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We present a new P wave and S wave velocity model for the upper crust beneath Long Valley Caldera obtained using local earthquake tomography and receiver function analysis. We computed the tomographic model using both a graded inversion scheme and a traditional approach. We complement the tomographic Vp model with a teleseismic receiver function model based on data from broadband seismic stations (MLAC and MKV) located on the SE and SW margins of the resurgent dome inside the caldera. The inversions resolve (1) a shallow, high‐velocity P wave anomaly associated with the structural uplift of a resurgent dome; (2) an elongated, WNW striking low‐velocity anomaly (8%–10 % reduction in Vp) at a depth of 6 km (4 km below mean sea level) beneath the southern section of the resurgent dome; and (3) a broad, low‐velocity volume (∼5% reduction in Vp and as much as 40% reduction in Vs) in the depth interval 8–14 km (6–12 km below mean sea level) beneath the central section of the caldera. The two low‐velocity volumes partially overlap the geodetically inferred inflation sources that drove uplift of the resurgent dome associated with caldera unrest between 1980 and 2000, and they likely reflect the ascent path for magma or magmatic fluids into the upper crust beneath the caldera.
    Description: Published
    Description: B12314
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Seismic Tomography ; Long Valley Caldera ; Receiver Function ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
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  • 92
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    Time reverse location of seismic long-period events recorded on Mt Etna (2012)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.
    Description: Published
    Description: 452-462
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Computational seismology ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 93
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    The mechanics of lubricated faults: Insights from 3-D numerical models (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-03
    Description: The weakening mechanisms occurring during an earthquake failure are of prominent importance in determining the resulting energy release and the seismic waves excitation. In this paper we consider the fully dynamic response of a seismogenic structure where lubrication processes take place. In particular, we numerically model the spontaneous propagation of a 3-D rupture in a fault zone where the frictional resistance is controlled by the properties of a low viscosity slurry, formed by gouge particles and fluids. This model allows for the description of the fault motion in the extreme case of vanishing effective normal stress, by considering a viscous fault response and therefore without the need to invoke, in the framework of Coulomb friction, the generation of the tensile mode of fracture. We explore the effects of the parameters controlling the resulting governing law for such a lubricated fault; the viscosity of the slurry, the roughness of the fault surfaces and the thickness of the slurry film. Our results indicate that lubricated faults produce a nearly complete stress drop (i.e., a very low residual friction coefficient; mu ~ 0.01), a high fracture energy density (E_G ~ few 10s of MJ/m^2) and significant slip velocities (vpeak ~ few 10s of m/s). The resulting values of the equivalent characteristic slip-weakening distance (d_0_eq = 0.1–0.8 m, depending on the adopted parameters) are compatible with the seismological inferences. Moreover, in the framework of our model we found that supershear ruptures are highly favored. In the case of enlarging gap height we can have the healing of slip or even the inhibition of the rupture. Quantitative comparisons with different weakening mechanisms previously proposed in the literature, such as the exponential weakening and the frictional melting, are also discussed.
    Description: Published
    Description: B05304
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: restricted
    Keywords: governing models ; theoretical seismology ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 94
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    Sulfur isotopic compositions of fumarolic and plume gases at Mount Etna (Italy) and inferences on their magmatic source (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-03
    Description: Here we report new data on the sulfur isotopic compositions (d34S) of fumarolic and plume gases collected at Mount Etna volcano during 2008–2009. While low-temperature fumaroles are affected by postmagmatic processes that modify the pristine isotopic signature, high-temperature and plume gases allow establishment of a d34S range of 0 1‰ for magmatic SO2. We compared our data with those from S dissolved in primitive melt inclusions from 2002 lava and in whole rocks that erupted during the past two thousand years. Such a comparison revealed that d34S is systematically lower for magmatic gases than for sulfur dissolved in the melt. We modeled how isotopic fractionation due to magma degassing process may vary d34S value in both the melt and gaseous phases. This modeling required assessment of the fractionation factor (agas-melt). The most recent measurements on the oxidation state of sulfur in basaltic melt inclusions indicate that nearly all S is dissolved as sulfate (S6+), which would be possible in oxidized magmatic systems (DNNO ≥ 1). Under these conditions the exsolved gaseous phase is depleted with respect to the melt and the proposed model fits both gas and melt data, and constrains the Etnean magmatic d34S to 1.0 1.5‰. It is remarkable that the assessed redox conditions—which are significantly more oxidizing than previously thought—are able to explain why the dominant sulfur species measured in the Etnean plume is SO2.
    Description: Published
    Description: Q05015
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: Mount Etna ; SO2 ; degassing ; fumarole ; plume ; sulfur isotope ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 95
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    Crustal changes at Mt. Etna volcano accompanying the 2002–2003 eruption as inferred from a repeating earthquake analysis (2012)
    American Geophysical Union
    Details
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 96
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    Volcanic edifice weakening via decarbonation: A self-limiting process? (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: The inherent instability of volcanic edifices, and their resultant propensity for catastrophic collapse, is a constant source of volcanic risk. Structural instability of volcanic edifices may be amplified by the presence of carbonate rocks in the sub-volcanic strata, due to the debilitating response of carbonates to thermally-induced alteration. Nonetheless, decarbonation reactions (the primary weakening mechanism), may stall when the system becomes buffered by rising levels of a reaction product, carbon dioxide. Such thermodynamic stalling might be inferred to serve to circumvent the weakness of volcanic structures. However, the present study shows that, even when decarbonation is halted, rock physical properties continue to degrade due to thermal microcracking. Furthermore, as a result, the pathways for the escape of carbon dioxide are numerous within a volcanic edifice. Therefore, in the case of an edifice with a subvolcanic sedimentary basement, the generation of carbon dioxide via decarbonation is unlikely to hinder its impact on instability, and thus potentially devastating flank collapse.
    Description: Published
    Description: L15307
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: restricted
    Keywords: volcanic weakening; decarbonation ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks
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  • 97
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    GPS velocity and strain fields in Sicily and southern Calabria, Italy: updated geodetic constraints on tectonic block interaction in the central Mediterranean (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We present an improved rendition of the geodetic velocity and strain fields in Sicily and southern Calabria obtained through the analysis of 18 years of GPS observations from continuous and survey station networks. The dense spatial coverage of geodetic data provides precise quantitative estimates of previously established first-order active kinematic features, including: i) a narrow east-west-elongated belt of contraction (~1-1.5 mm/yr) extending offshore northern Sicily from Ustica to Stromboli across the Aeolian Islands; ii) a narrow east-west-trending contractional belt located along the northern rim of the Hyblean Plateau in southern Sicily, with shortening at up to 4.4 mm/yr; iii) right motion (~3.6 mm/yr) on the Aeolian-Tindari-Letojanni fault (ATLF) system, a main shear zone extending from the Aeolian Islands to the Ionian coast of Sicily, with significant transpression and transtension partitioned between discrete sectors of the fault; iv) transtension (~1 mm/yr) across the Sicily Channel between Sicily and North Africa. We use geodetic observations coupled to geological constraints to better elucidate the interplay of crustal blocks revealed in the investigated area. In particular, we focus on the ATLF, which forms the primary boundary between the Sicilian and Calabrian blocks. The ATLF juxtaposes north-south contraction between Sicily and the Tyrrhenian block with northwest-southeast extension in north-eastern Sicily and Calabria. Contraction between Sicily and Tyrrhenian blocks probably arises from the main Europe-Nubia convergence, although Sicily has a component of lateral motion away from Nubia. We found that convergence is not restricted to the northern offshore, as commonly believed, but is widely accommodated between the frontal belt and the northern rim of the Hyblean foreland in southern Sicily. Geodetic data also indicate that active right shear on the ATLF occurs to the southeast of the mapped fault array in northern Sicily, suggesting the fault cuts through till the Ionian coast of the island. The small geodetic divergence between the Hyblean and Apulian blocks rimming on both sides the Calabria block and subjacent Ionian slab, coupled with marine geophysical evidences in the Ionian Sea lends credit to the proposed deep root of the ATLF and to a fragmentation of the Ionian domain.
    Description: Published
    Description: B07401
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Calabro Peloritan Arc ; Geodesy ; plate tectonic ; Strain-rate ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
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  • 98
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    Unraveling the geometry of the New England oroclines (eastern Australia): Constraints from magnetic fabrics (2014)
    American Geophysical Union
    Details
    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
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  • 99
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    Paleomagnetism and magnetic fabric of the Eastern Cordillera of Colombia: Evidence for oblique convergence and non rotational reactivation of a Mesozoic intracontinental rift (2014)
    American Geophysical Union
    Details
    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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  • 100
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    Insights into magma and f luid transfer at Mount Etna by a multiparametric approach: A model of the events leading to the 2011 eruptive cycle (2013)
    American Geophysical Union
    Details
    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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