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  • 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations  (9)
  • 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology  (6)
  • Mixing
  • American Geophysical Union  (9)
  • Elsevier Science Limited  (6)
  • Elsevier Science  (1)
  • American Institute of Physics (AIP)
  • 2010-2014  (16)
  • 1985-1989
  • 2012  (16)
Collection
Years
  • 2010-2014  (16)
  • 1985-1989
Year
  • 1
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
    Publication Date: 2020-12-15
    Description: The source properties of the Long-Period events that occurred at Campi Flegrei Caldera (Italy) during the 2004–2006 ground uplift episode are investigated by analyzing the temporal release of seismic energy, amplitude distribution and inter-event occurrence time. Moreover, an entropy-based decomposition method is applied to identify the simpler waveforms thought to be representative of the source mechanism of Long-Period events. On the basis of the outcomes, we propose that the main part of these events is the result of a source process triggered by a mechanism of fluid charge/discharge, which causes pressure drop in a main branch of a dentritic network of the hydrothermal system. In this model, the rate of the Poissonian process (about 15 min), which drives the occurrence of the Long-Period events, provides the average recharge time of the system up to the critical condition. A partial shunting of the fluid flow away from the main conduit activates the ”resonance” of a second branch, spatially separated from the first one. This is a process that occurs whenever the fluid pressure exceeds a critical value and produces less energetic Long-Period events. The mechanism of pressure variation in the two conduits generates signals with preferred amplitude scales, described by a bi-lognormal distribution. From a dynamical point of view, Long-Period events result well described by a low-dimensional dynamical system. Finally, the time pattern of the energy release and its correlation with the diurnal solid earth tide suggest that the whole mechanism of fluid charge/discharge is likely modulated by tidal stress variation.
    Description: Published
    Description: 16-30
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: partially_open
    Keywords: Lp sources ; Poissonian occurrence ; Tidal modulation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
    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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  • 5
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2017-04-04
    Description: Calabria is one of themost complex geological regions of the Mediterranean basin, which experienced large earthquakes and uplift and is still undergoing active tectonics. Along its coasts are located archaeological sites that can be used as powerful indicators of the relative vertical movements between land and sea since their construction. This paper presents and discusses data on the relative sea-level change as estimated from maritime archaeological indicators of the last w2.0 ka BP existing along the Tyrrhenian coast of Briatico. These sites still showthe remnants of a Roman age fish tank and a submerged breakwater about 320mlong. The palaeo sea level has been obtained measuring the functional elevation of the significant archaeological markers. Their elevationwas compared against the latest predicted sea level curve for the Holocene along the Tyrrhenian coast of Calabria. As this coastal area is affected by significant and continuous vertical tectonic uplift during Pleistocene, the data show the counterbalance between coastal uplift and relative sea level change caused by the glacio-hydro-isostasy, acting since the construction of these archaeological sites. The sum of these movements determined an about null relative sea level change for this location. These data are in contrast with other part of the tectonically stable areas of the Mediterranean and provide evidence that crustal uplift continued in the last 1806+/- 50 y at a rate of 0.65 mm/y.
    Description: Published
    Description: 158-167
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Calabria, archaeology, vertical tectonics, sea level ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2017-04-04
    Description: From October 2008 to November 2009, soil CO2, radon and structural field surveys were performed on Mt. Etna, in order to acquire insights into active tectonic structures in a densely populated sector of the south-eastern flank of the volcano, which is involved in the flank dynamics, as highlighted by satellite data (InSAR). The studied area extends about 150 km2, in a sector of the volcano where InSAR results detected several lineaments that were not well-defined from previous geological surveys. In order to validate and better constrain these features with ground data evidences, soil CO2 and soil radon measurements were performed along transects roughly orthogonal to the newly detected faults, with measurement points spaced about 100 m. In each transect, the highest CO2 values were found very close to the lineaments evidenced by InSAR observations. Anomalous soil CO2 and radon values were also measured at old eruptive fractures. In some portions of the investigated area soil gas anomalies were rather broad over transects, probably suggesting a complex structural framework consisting of several parallel volcano-tectonic structures, instead of a single one. Soil gas measurements proved particularly useful in areas at higher altitude on Mt. Etna (i.e. above 900 m asl), where InSAR results are not very informative/ are fairly limited, and allowed recognizing the prolongation of some tectonic lineaments towards the summit of the volcano. At a lower altitude on the volcanic edifice, soil gas anomalies define the active structures indicated by InSAR results prominently, down to almost the coastline and through the northern periphery of the city of Catania. Coupling InSARwith soil gas prospectingmethods has thus proved to be a powerful tool in detecting hidden active structures that do not show significant field evidences.
    Description: This work was funded by the DPC-INGV project “Flank”
    Description: Published
    Description: 27-40
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: CO2 ; Radon ; InSAR ; Faults ; Etna ; Volcano-tectonics ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    Publication Date: 2017-04-04
    Description: Volcanic rift zones, characterized by repeated dike emplacements, are expected to delimit the upper portion of unstable flanks at basaltic edifices. We use nearly two decades of InSAR observations excluding wintertime acquisitions, to analyze the relationships between rift zones, dike emplacement and flank instability at Etna. The results highlight a general eastward shift of the volcano summit, including the northeast and south rifts. This steadystate eastward movement (1-2 cm/yr) is interrupted or even reversed during transient dike injections. Detailed analysis of the northeast rift shows that only during phases of dike injection, as in 2002, does the rift transiently becomes the upper border of the unstable flank. The flank's steady-state eastward movement is inferred to result from the interplay between magmatic activity, asymmetric topographic unbuttressing, and east-dipping detachment geometry at its base. This study documents the first evidence of steady-state volcano rift instability interrupted by transient dike injection at basaltic edifices.
    Description: Partially funded by INGV and the Italian DPC (DPC-INGV project V4 “Flank”). ERS and ENVISAT SAR data were provided by ESA through the Cat-1 project no. 4532 and the GEO Supersite initiative. The DEM was obtained from the SRTM archive. ERS-1/2 orbits are courtesy of the TU-Delft, The Netherlands. SAR data processing has been done at IREACNR, partially carried out under contract “Volcanic Risk System (SRV)” funded by the Italian Space Agency (ASI).
    Description: Published
    Description: L20311
    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: restricted
    Keywords: flank instability ; rift zones ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques ; 04. Solid Earth::04.04. 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::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2017-04-04
    Description: One hundred twenty-nine long-period (LP) events, divided into two families of similar events, were recorded by the 50 stations deployed on Mount Etna in the second half of June 2008. During this period lava was flowing from a lateral fracture after a summit Strombolian eruption. In order to understand the mechanisms of these events, we perform moment tensor inversions. Inversions are initially kept unconstrained to estimate the most likely mechanism. Numerical tests show that unconstrained inversion leads to reliable moment tensor solutions because of the close proximity of numerous stations to the source positions. However, single forces cannot be accurately determined as they are very sensitive to uncertainties in the velocity model. Constrained inversions for a crack, a pipe or an explosion then allow us to accurately determine the structural orientations of the source mechanisms. Both numerical tests and LP event inversions emphasise the importance of using stations located as close as possible to the source. Inversions for both families show mechanisms with a strong volumetric component. These events are most likely generated by cracks striking SW–NE for both families and dipping 70° SE (family 1) and 50° NW (family 2). For family 1 events, the crack geometry is nearly orthogonal to the dikelike structure along which events are located, while for family 2 the location gave two pipelike bodies that belong to the same plane as the crack mechanism. The orientations of the cracks are consistent with local tectonics, which shows a SW–NE weakness direction. The LP events appear to be a response to the lava fountain occurring on 10 May 2008 as opposed to the flank lava flow.
    Description: Published
    Description: B01304
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Etna Volcano ; long-period events ; source mechanism ; location ; plumbing systems ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2017-04-04
    Description: The inversion of multitemporal DInSAR and GPS measurements unravels the coseismic and postseismic (afterslip) slip distributions associated with the 2009 MW 6.3 L’Aquila earthquake and provides insights into the rheological properties and long-term behavior of the responsible structure, the Paganica fault. Well-resolved patches of high postseismic slip (10–20 cm) appear to surround the main coseismic patch (maximum slip ≈1 m) through the entire seismogenic layer above the hypocenter without any obvious depth-dependent control. Time series of postseismic displacement are well reproduced by an exponential function with best-fit decay constants in the range of 20–40 days. A sudden discontinuity in the evolution of released postseismic moment at ≈130 days after the main shock does not correlate with independent seismological and geodetic data and is attributed to residual noise in the InSAR time series. The data are unable to resolve migration of afterslip along the fault probably because of the time interval (six days) between the main shock and the first radar acquisition. Surface fractures observed along the Paganica fault follow the steepest gradients of postseismic line-of-sight satellite displacements and are consistent with a sudden and delayed failure of the shallow layer in response to upward tapering of slip. The occurrence of afterslip at various levels through the entire seismogenic layer argues against exclusive depth-dependent variations of frictional properties on the fault, supporting the hypothesis of significant horizontal frictional heterogeneities and/or geometrical complexities. We support the hypothesis that such heterogeneities and complexities may be at the origin of the long-term variable behavior suggested by the paleoseismological studies. Rupture of fault patches with dimensions similar to that activated in 2009 appears to have a ≈500 year recurrence time interval documented by paleoseismic and historical studies. In addition to that, paleoseismological evidence of large (〉0.5 m) coseismic offsets seems to require seismic events, recurring every 1000–2000 years, characterized by (1) multisegment linkage, (2) surface ruptures larger than in 2009, and (3) complete failure of the 2009 coseismic and postseismic patches.
    Description: Published
    Description: B02402
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Afterslip ; L'Aquila ; Apennines ; postseismic ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2017-04-04
    Description: We analyze the kinematic and crustal deformations of Mt. Etna from 2003 to 2008 as imaged by the Mt. Etna continuous GPS (CGPS) network (Etna@net). Through a careful analysis of GPS time series, six coherent phases of crustal deformations have been identified, three inflation phases and three deflation phases, superimposed on a major inflation of the volcanic edifice since 2001. The inversions of GPS velocities have enabled: 1) a better understanding of the evolution of the volcanic sources acting beneath the volcano; 2) analysis of the strain rate patterns; and 3) a delineation of potential coupling between volcanic sources and the observed ground deformations. The modelling of the pressure sources has shown a separation between inflation and deflation sources. The deflation sources show an upward migration, from 5.5 toward 2.0 km (b.s.l.), while the inflation sources are located within 5.5 and 4.0 km (b.s.l.). Our results indicate that the kinematic and ground deformations of the mid-upper eastern flank are driven by the interplay between the effect of the magmatic sources and a south-eastward motion. Furthermore, clockwise rotations have been detected that prevailed over the eastern motion of the flank during the inflation phase preceding the 2004-2005 and 2006 eruptions. Finally, the accordance between the higher geodetic shear strain rates and the area with the highest seismic energy release shows that measured geodetic shear strain rates can provide useful information on the potential occurrence of seismic activity.
    Description: Osservatorio Etneo, Istituto Nazionale di Geofisica e Vulcanologia,Catania, Italy. Department of Geosciences, State University of New York at Stony Brook, Stony Brook, New York, USA.
    Description: Published
    Description: B07208
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: Mt. Etna ground deformations ; Volcano monitoring ; Strain rate analysis ; Volcanic source modelling ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publication Date: 2017-04-04
    Description: At Stromboli volcano, Italy, continuous seismic monitoring and periodic, visual observations of volcanic activity for surveillance purposes began in the mid-1980s. Since 1985, two eruptions have occurred, one lasting from December, 1985 until April, 1986, and one in May, 1993. There have also been two small overflows, in 1990 and 1994. Since these episodes of lava effusion, the persistent Strombolian activity of the volcano has had several fluctuations during the past 15 years. Some episodes climaxed in powerful explosions. According to seismic records, these paroxysms consisted of a variable number of explosion quakes in rapid succession (i.e. from tens of seconds to a few minutes), associated with a notable increment in the amplitude of volcanic tremor. Throughout these episodes - which are called explosive sequences - lapilli, fragments of old rock, and bombs of varying dimensions were ejected, affecting an area greater than the crater terrace where the active craters are located. In this article, we describe the explosive sequences recorded at Stromboli between 1985 and 1999. We provide a characterization in terms of reduced displacement and duration for nine episodes occurring in 1998 and 1999. Their reduced displacements range from 15 to 124 cm2; their durations are between 6 and 18 min. We find no change in the frequency content of the seismic signal several minutes before and during the sequences. Considering medium- to long-term behavior, the spectral amplitude of the seismic signal decreases or has low values over several months preceding the occurrence of the paroxysms. This feature is common to 20 of the 22 explosive sequences, and is indicative of internal conditions that periodically characterize the feeder. We surmise that the paroxysms are the result of the partial obstruction of the volcanic conduit when the magma column is low or dropping. The onset of the explosive sequence, causing the sudden removal of the material which forms the obstruction, would trigger a sudden depressurization of the conduit and the rapid rise of magma from depth.
    Description: Published
    Description: 137-150
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; Paroxysms ; Seismicity ; Volcanoes ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
    Publication Date: 2017-04-04
    Description: Crustal tectonic seismicity in the Southern Tyrrhenian Sea is characterized by the high occurrence rates of earthquakes to the west of the alignment of Salina, Lipari and Vulcano islands in the Aeolian archipelago. Only a few earthquakes affect the crustal region east of these islands, whereas intermediate and deep seismicity plays a relevant role. Based on this evidence, two aspects of the seismic swarm recorded at the Aeolian Island Seismic Network between June 6 and 17, 1999 looked anomalous. The first aspect concerned the number of earthquakes (78) that affected the Stromboli submarine edifice in a short time interval. Secondly, despite the low maximum magnitude Md 3.2 reached, the cumulative strain release was conspicuous in comparison with previous swarms in this region. We localized the swarm about 6 km northeast of Stromboli, at a depth between 8 and 12km. The source region was identified using standard methods of hypocentral location, as well as azimuth analysis. It is worth noting that the volcanic activity at Stromboli did not change significantly during the swarm nor throughout the following months. Therefore, the seismic swarm had no link with volcanic activity observed at the surface. Most of the earthquakes shared similar waveform and frequency content, and can be divided into families. We identified some earthquakes - with magnitude up to Md 3 - having relatively low frequency content at different seismic stations. This anomalous feature leads us to hypothesize the presence of fluid circulation and/or propagation of seismic waves in a ductile medium. Our hypothesis is in agreement with studies on marine geology, which highlight various forms of submarine volcanism in the southern basin of the Tyrrhenian Sea.
    Description: This work was financially supported by the EC project MULTIMO (Contract No. EVG1-CT-2000-00021).
    Description: Published
    Description: 121-136
    Description: JCR Journal
    Description: reserved
    Keywords: Earthquakes ; Seismic swarm ; Volcanoes ; Stromboli ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2017-04-04
    Description: InSAR (Interferometric Synthetic Aperture Radar) techniques are applied to investigate last two decades of surface deformation of the Cerro Blanco/Robledo Caldera (CBRC). The objective is the identification of deforming patterns that alter the shape of these complex structures when they show low or null activity. The joint analysis between results by using different methods over a long time span, represents a unique opportunity to improve knowledge of volcanic structures located in remote area and, for this, poorly or not monitored. In this work we identify displacement patterns over the volcanic area, by using both classical differential InSAR analysis, and A-InSAR (Advanced InSAR) analysis based on SAR data acquired by ERS-1/2 and ENVISAT sensors during the 1996-2010 time interval. The satellite-derived information allows us to characterize the deformation pattern that affected the CBRC and shows that the actively deforming CBRC is subsiding in the observed period. In order to figure out the deformation history of CBRC, we analyzed the four sub-periods 1992-1996, 1996-2000, and 2005-2010 by using standard differential InSAR technique, and the interval 2003-2007 by adopting an A-InSAR technique. Subsidence velocities of the CBRC caldera are about 2.6 cm/yr in the time interval 1992-1996 (measured with ERS descending data), 1.8 cm/yr in 1996-2000 (ERS descending data), 1.2 cm/yr in 2003-2007 (ENVISAT descending data),and finally, 0.87 cm/yr in 2005-2010 (ENVISAT ascending data). Moreover, outside the caldera and in particular in the NW area, we observe the presence of positive velocity values. Results show that: a) a decreasing subsidence rate might be related to the reduction of volcanic activity in correspondence of the CBRC; b) positive velocity signal, decreasing with time, might be interpreted as follows: - evidence of volcano structure lateral spreading, according to the velocity pattern distribution in this area and to the relative local flanks topographic convexity of the volcano structure; - uplift signal of this sector of mountain chain; - combination if the two mechanisms above.
    Description: Published
    Description: 279–287
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: open
    Keywords: : InSAR; A-InSAR; Deflation; Calderas; Volcanic structures ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 15
    Publication Date: 2017-04-04
    Description: The Pernicana–Provenzana Fault System is one of the most active tectonic systems of Mt. Etna and it plays an important role in the dynamic of the eastern flank of the volcano. Earthquakes occurring close to this structural trend have reached magnitudes up to 4.2, sometimes with coseismic surface faulting, and have caused severe damages to tourist resorts and villages in the vicinity of this structure. In the last decade, a large number of shocks, sometimes in the form of swarms, linked to Pernicana–Provenzana Fault System movements have been detected by the permanent local seismic network operating in eastern Sicily. In this paper, we report on the detailed study of the seismic activity occurring during the 2000–2009 time span in the Pernicana–Provenzana Fault System area. Firstly, we located 407 earthquakes using a standard location code and a 1D crustal velocity model. We then applied two different approaches to calculate precise hypocenter locations of the events. In particular, a non-linear code was adopted to obtain an estimate of the a posteriori Probability Density Function in 3D space for the hypocenter location. Moreover, a relative location of correlated event pairs was performed, using the double-difference method. These two different location approaches allowed defining with good accuracy, the most active and hazarding sectors of the structure. The results of these precise locations showed a tighter clustering in the epicenters and in focal depths, in comparison with standard locations. Earthquakes are located along the Pernicana–Provenzana Fault System, and are mainly clustered in two zones, separated by an area with very low rate of earthquakes occurrence, but characterized by the highest energy release. Depths of the foci are very shallow, ranging between the surface and about 3 km b.s.l. Kinematics of the Pernicana–Provenzana Fault System, revealed by the fault plane solutions computed for the most energetic earthquakes, highlights a predominant dip–slip and left strike movements along E–W oriented fault planes, in agreement with field observations.
    Description: Published
    Description: 16-26
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Etna volcano ; Pernicana–Provenzana Fault System ; Earthquakes ; Precise location ; Fault plane solutions ; Seismic strain release ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 16
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): C02027, doi:10.1029/2011JC007033.
    Description: Observations of the spatial distribution and persistence of thermohaline structure are presented, and show how advection and diffusion affect a passive tracer. More than two years of underwater glider observations in the central subtropical North Pacific showed thermohaline variability over horizontal scales from 5 to 1300 km. Thermohaline fluctuations along isopycnals (spice fluctuations) were elevated in layers throughout the water column with the largest fluctuations near the surface and subtropical frontal regions. Fluctuations were uncorrelated between the layers but stirred by the same velocity field. Spice variance had local extrema in the vertical because of differences in source water properties and the influence of neighboring water masses. Spice variance spanned about three orders of magnitude along deeper isopycnals with larger variance where different water masses met and where velocity and vorticity variance were elevated. Horizontal wave number spectra of spice had slopes of −2 everywhere in the upper 1000 m. Submesoscale spice fluctuations had slopes in physical space near the ratio of the Coriolis parameter to the buoyancy frequency (f/N), consistent with predictions of quasi-geostrophic theory. In the mixed layer, thermohaline structure had a significant annual cycle with smaller interannual differences. Thermohaline fluctuations left behind during restratification and isolated from the mixed layer decayed with time because of diffusion along isopycnals. Horizontal diffusivity estimates in the remnant mixed layer were 0.4 m2 s−1 at 15–28 km wavelengths and 0.9 m2 s−1 at 35–45 km wavelengths.
    Description: We gratefully acknowledge the National Science Foundation for funding this work under grant number OCE0452574.
    Description: 2012-08-18
    Keywords: Diffusion ; Mixing ; Spice ; Stirring ; Thermohaline structure
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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