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  • 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology  (41)
  • 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics  (33)
  • Elsevier  (45)
  • AGU  (28)
  • Annual Reviews
  • 2020-2024
  • 2005-2009  (73)
  • 2000-2004
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  • 1985-1989
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  • 1960-1964
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  • 1
    Publication Date: 2020-11-26
    Description: During the July^August 2001 eruption of Mt. Etna development of extensional fractures/faults and grabens accompanied magma intrusion and subsequent volcanic activity. During the first days of the eruption, we performed an analysis of attitude, displacement and propagation of fractures and faults exposed on the ground surface in two sites, Torre del Filosofo and Valle del Leone, located along the same fracture system in the region surrounding the Valle del Bove depression on the eastern flank of Mt. Etna. Fractures and faults formed as the consequence of a shallow intruding dyke system that fed the several volcanic centres developed along the fracture system. The investigated sites differ in slope attitude and in geometrical relationships between fractures and slopes. In particular, the fracture system propagated parallel to the gentle slope (67‡ dip) in the Torre del Filosofo area, and perpendicular to the steep slope (V25‡ dip) in the Valle del Leone area. In the Torre del Filosofo area, slight graben subsidence and horizontal extension of the ground surface by about 3 m were recorded. In the Valle del Leone area, extensional faulting forming a larger and deeper graben with horizontal extension of the ground surface by about 10 m was recorded. For the Valle del Leone area, we assessed a downhill dip of 14‡ for the graben master fault at the structural level beneath the graben where the fault dip shallows. These results suggest that dyke intrusion at Mount Etna, and particularly in the region surrounding the Valle del Bove depression, may be at the origin of slope failure and subsequent slumps where boundary conditions, i.e. geometry of dyke, slope dip and initial shear stress, amongst others, favour incipient failures.
    Description: Published
    Description: 281-294
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: dykes ; extensional fractures ; grabens ; slope failures ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. 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::04.08.05. Volcanic rocks ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 2
    Publication Date: 2020-12-03
    Description: A study of the He isotopic ratios of fluid inclusions in olivine and pyroxene from the Roman Comagmatic Province (RCP),Italy, is presented together with 87Sr/86Sr isotope compositions of the whole rock or pyroxene phenocrysts. A clear covariation in He and Sr isotopes is apparent, with a strong northward increase in radiogenic He and Sr being evident. He and Sr isotopes ratios range from 3He/4He = 5.2 Ra and 87Sr/86Sr = 0.7056 in south Campania, to 3He/4He = 0.44 Ra and 87Sr/86Sr = 0.715905 in the northernmost Latium. Helium isotope ratios are significantly lower than MORB values and are among the lowest yet measured in subduction zone volcanism. The 3He/4He of olivine and pyroxene phenocryst-hosted volatiles appear to be little influenced by posteruptive processes and magma–crust interaction. The 3He/4He–87Sr/86Sr covariation is consistent with binary mixing between an asthenospheric mantle similar to HIMU ocean island basalts, and an enriched (radiogenic) mantle end member generated from subduction of the Ionian/Adriatic plate. The contribution of radiogenic He from metasomatic fluids and postmetasomatism radiogenic ingrowth in the wedge is strongly dependent on the initial He concentration of the mantle. Only when asthenosphere He concentrations are substantially lower than the MORB source mantle, and metasomatism occurred at the beginning of the subduction (f30 Ma), can ingrowth in the mantle wedge account for the 3He/4He of the most radiogenic basalts.
    Description: - European Social Fund - Scottish Universities - Carnegie Trust for the Universities of Scotland.
    Description: Published
    Description: 295–308
    Description: partially_open
    Keywords: Roman Comagmatic Province ; fluid inclusions ; helium ; strontium ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
    Publication Date: 2020-12-15
    Description: The eruptive events of the July–August 2001 and October 2002–January 2003 at Mt. Etna provide new insights for reconstructing the complex geometry of the feeding system and their relationship to regional tectonics. The 2001 eruption took place mainly on the upper southern sector of the volcano. The eruption was preceded by a large earthquake swarm for a few days before its onset and accompanied by ground deformation and fracturing. The development of surface cracking along with the seismic pattern has allowed us to recognize three distinct eruptive systems (the SW–NE, NNW–SSE and N–S systems) which have been simultaneously active. Such eruptive systems are only the upper portions of a complex feeding system that was fed at the same time by two distinct magmas. The SW–NE and NNW–SSE systems, connected with the SE crater conduit, were fed by magma coming from depth, whereas the N–S system served instead as an ascending pathway for an amphibole-bearing magma residing in a shallow reservoir. The eruptive activity started again on October 2002 on the NE Rift Zone, where about 20 eruptive vents were aligned between 2500 and 1900 m a.s.l., and on the southern flank, from the central crater to the Montagnola. The onset of eruptive activity was accompanied by a seismic swarm. As in the 2001 eruptive event, two independent feeding systems formed, characterized by distinct magmas. The SW–NE system controlled the feeding of the Northeast Rift and was accommodated by left-lateral displacement along the WNW–ESE trending Pernicana Fault. The N–S system fed the eruptions on the southern flank. Moreover, the associated crustal deformation triggered seismic reactivation of tectonic structures in the eastern flank of the volcano and offshore. These two last eruptions indicate that at Mt. Etna the ascent of magma, as well as the accommodation of deformation, is strongly dominated by local extensional structures that are connected to a regional tectonic regime.
    Description: Published
    Description: 211-233
    Description: partially_open
    Keywords: extensional tectonics ; volcanic activity ; seismicity ; Sicily ; Mt. Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 4
    Publication Date: 2017-04-04
    Description: Seismic activity linked to the 2002–03 Mt. Etna eruption was investigated by analyzing the Md 〉 2.3 earthquakes. The results of 3D relocation were used to compute fault plane solutions and a selected dataset was inverted to determine stress and strain tensors. The analysis revealed a complex kinematic response of the eastern flank dominated by fast stress propagation and reorientation. We hypothesize that a vertical dike intruded the southern flank, generating an extensional regime that triggered a radial intrusion in the northeast sector of the volcano. The combined effects gave rise to a rotation of the stress tensor that controlled the activation of the Pernicana fault system. The volcanic and tectonic interactions produced a second reorientation of the stress tensor, causing a structural response in the southeast lower flank. The overall result of the deformation processes observed during the eruption was an E-W extension on the eastern flank of the volcano.
    Description: Published
    Description: 4
    Description: partially_open
    Keywords: Seismology: Seismicity and seismotectonics ; Seismology: Volcano seismology ; Volcanology: Eruption mechanisms ; Volcanology: Magma migration ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 5
    Publication Date: 2017-04-04
    Description: The properties of volcanic tremor wavefield at Mt. Etna Volcano, Italy, are investigated using data from two dense, smallaperture arrays of short-period seismometers deployed on the North and South flank of the volcano. Spectral analysis shows that most of the seismic energy is associated to several, narrow spectral peaks spanning the 1–5 Hz frequency band. Analysis of simultaneous recordings evidences that most of these peaks are common to different sites, thus suggesting a source effect as the origin of this energy. Frequency-slowness analyses evidence a complex wavefield, where body- and surface-waves alternatively dominate depending on the frequency band and component of motion taken into account. Surface waves are found to dominate at frequencies below 1 Hz and above 3 Hz. Conversely, the 0.8–2.3 Hz vertical- and radial-component wavefields at both arrays exhibit a nondispersive nature, with apparent velocities spanning the 1–2 s/km range. Particle motion analysis suggests these arrivals are associated to both P- and SV-waves inciding at shallow angles. At the northern array, back-azimuths of these waves encompass the whole summit crater area. At the southern array, back-azimuths are instead clustered around a direction pointing about 500 m east of the SE crater. At frequency around 4 Hz, the dominant direction of wave propagation at the southern site shifts about 30jW, pointing to the Bocca-Nuova/Voragine craters, and concordance of location is found with the source imaged by the northern array. The 0.8–2.3 Hz transverse-component of motion depicts velocities of about 0.5 km/s, a value which is about three times lower than those associated to the vertical and radial components. Results from polarization analyses at the two array sites depict the dominance of horizontal, linear particle motion oriented transversally with respect to the source direction. Polarization ellipsoids at the stations of the sparse network all depict a quasi-horizontal setting. With two exceptions, the direction of particle motion is always oriented tangentially to the summit volcanic edifice. The origin of the large transverse motion observed at the two array sites is thus attributed to SH waves generated by free-surface interaction of waves impinging the concave topography. The correlation method is used to derive the dispersion properties of short-period (0.5–5 Hz) Rayleigh waves, from which the shallow shear-wave velocity structures are derived for beneath the two semicircular arrays. Using a probabilistic approach, we invert slowness data measured at the two dense arrays for retrieving source location and extent. The joint inversion of slowness data from the two arrays point to different sources. This observation is interpreted in terms of ray bending associated to lateral heterogeneity and/or strong topographic effects on wave propagation. Once the propagation effects are taken into account, the most probable source locations are associated to a shallow region encompassing the summit craters and the eruptive fissures active at the time of the experiment (September 1999).
    Description: Published
    Description: 223-245
    Description: partially_open
    Keywords: Mount Etna ; Volcanic tremor ; Volcanic seismicity ; Seismic monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2017-04-04
    Description: On October 9, 1999 an earthquake of ML =3.6 occurred about 3 km beneath the central cone of Mt. Vesuvius, near Naples, Italy. The event had the highest magnitude recorded for at least 25 years, and possibly since the last eruption of this volcano (1944), and was not accompanied by other geophysical or geochemical changes. The present paper essentially deals with the seismological data collected at Mt. Vesuvius for 29 years before the October 9 earthquake till the end of 2001, and describes the time pattern distribution of seismic slip release and the b-parameter of the Gutenberg^Richter distribution. The self-similarity of the source process is investigated through the scaling law of the seismic spectrum. Results indicate a two-fold pattern of stress release, with high values (up to 100 bar) for earthquakes occurring close to the top of the carbonate basement that underlies the volcano at 2^3 km of depth, and low values (down to 0.1 bar) for the shallow events occurring within the volcanic edifice. The scaling law of the seismic spectrum is non-self-similar, indicating that the source dimensions do not scale with the seismic moment. For this reason the low-magnitude events substantially contribute to the overall cumulative seismic slip release. The bparameter of the Gutenberg^Richter distribution shows a variation around 1980, and a substantial constancy in the other time periods. The presence of extended aquifers, with their tops at about 1 km beneath the crater, favors the hypothesis of the triggering of the shallowest events by water-level changes. This hypothesis is in agreement with the low values of the stress drop measured for the shallowest seismic events. The existence of a carbonate basement with its top at about 2.5 km beneath the crater and the higher stress drops for the deeper events make reasonable the hypothesis that the pre-fractured carbonate basement may be the site of tectonic stress release.
    Description: Published
    Description: 23-39
    Description: partially_open
    Keywords: Vesuvius ; Seismicity ; Seismic source ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2017-04-04
    Description: In the Apennines subduction (Italy), earthquakes mainly occur within overriding plate, along the chain axis. The events concentrate in the upper 15 km of the crust above the mantle wedge and focal solutions indicate normal faulting. In the foreland, the seismogenic volume affects the upper 35 km of the crust. Focal solutions indicate prevailing reverse faulting in the northern foreland and strike-slip faulting in the southern one. The deepening of the seismogenic volume from the chain axis to the foreland follows the deepening of the Moho and isotherms. The seismicity above the mantle wedge is associated with uplift of the chain axial zone, volcanism, high CO2 flux, and extension. The upward pushing of the asthenospheric mantle and the mantle-derived, CO2-rich fluids trapped within the crust below the chain axis causes this seismicity. All these features indicate that the axial zone of Apennines is affected by early rifting processes. In northern Italy, the widespread and deeper seismicity in the foreland reflects active accretion processes. In the southern foreland, the observed dextral strike-slip faulting and the lack of reverse focal solutions suggest that accretion processes are not active at present. In our interpretation of the Apennines subduction, the shallower seismicity of the overriding plate is due to the dynamics (uprising and eastward migration) of the asthenospheric wedge.
    Description: Published
    Description: Q02013
    Description: JCR Journal
    Description: open
    Keywords: Apenninnes ; crustal seismicity ; rifting ; subduction ; fluids ; geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes
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  • 8
    Publication Date: 2017-04-04
    Description: The development of the 2004–2005 eruption at Etna (Italy) is investigated by means of field surveys to define the current structural state of the volcano. In 2004–2005, a fracture swarm, associated with three effusive vents, propagated downslope from the SE summit crater towards the SE. Such a scenario is commonly observed at Etna, as a pressure increase within the central conduits induces the lateral propagation of most of the dikes downslope. Nevertheless, some unusual features of this eruption (slower propagation of fractures, lack of explosive activity and seismicity, oblique shear along the fractures) suggest a more complex triggering mechanism. A detailed review of the recent activity at Etna enables us to better define this possible mechanism. In fact, the NW–SE-trending fractures formed in 2004–2005 constitute the southeastern continuation of a N–S-trending fracture system which started to develop in early 1998 to the east of the summit craters. The overall 1998–2005 deformation pattern therefore forms an arcuate feature, whose geometry and kinematics are consistent with the head of a shallow flank deformation on the E summit of Etna. Similar deformation patterns have also been observed in analogue models of deforming volcanic cones. In this framework, the 2004–2005 eruption was possibly induced by a dike resulting from the intersection of this incipient fracture system with the SE Crater. A significant acceleration of this flank deformation may be induced by any magmatic involvement. The central conduit of the volcano is presently open, constantly buffering any increase in magmatic pressure and any hazardous consequence can be expected to be limited. A more hazardous scenario may be considered with a partial or total closing of the central conduit. In this case, magmatic overpressure within the central conduit may enhance the collapse of the upper eastern flank, triggering an explosive eruption associated with a landslide reaching the eastern lower slope of the volcano.
    Description: Published
    Description: 195–206
    Description: reserved
    Keywords: eruption triggering ; volcano-tectonics ; fracture fields ; flank spreading ; Mt. Etna ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 9
    Publication Date: 2017-04-04
    Description: In this paper, we discuss the possibility that the North Anatolian fault (NAF) results from the deep deformation of the slab beneath the Bitlis–Hellenic subduction zone. We described the tectonic evolution of the Anatolia–Aegean area in three main steps, before, during and after the formation of the NAF. We remark that the tectonic conditions that are assumed to have triggered the formation of the NAF, i.e. collision to the east and extension to the west, was already achieved before the onset of that strike-slip fault system. We also highlight that the formation of the NAF was accompanied by the uplift of the Turkish–Iranian plateau and by a surge of volcanism in the eastern Anatolia collisional area and probably by the acceleration of the Aegean trench retreat. We show tomographic images from global P-wave model of Piromallo and Morelli [C. Piromallo, A. Morelli, P wave tomography of the mantle under the Alpine–Mediterranean area, J. Geophys. Res. 108 (2003) doi: 10.1029/2002JB001757.] showing that the slab beneath the Bitlis collisional belt is not continuous and that its possible rupture pursues to the west at least up to Cyprus and possibly up to the eastern end of the Hellenic trench. All these observations suggest that the plate tectonic re-organization occurred in the Late Miocene–Early Pliocene in the region results from slab break-off in the Bitlis area and from its lateral propagation to the West. This idea is tested in analogue laboratory experiments, which confirm that the break of the slab under the collisional belt may trigger, (1) the acceleration of slab retreat to the west due to the increase in slab pull force, (2) the indentation of the continent in the collisional area and (3) produce the conditions that permit the lateral escape of material towards the west and the formation of the NAF.
    Description: Published
    Description: 85-97
    Description: JCR Journal
    Description: reserved
    Keywords: Mediterranean ; subduction ; collision ; analogue experiments ; seismic tomography ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2017-04-04
    Description: On April 5, 2003, one of the largest eruptions in the last decades was observed at Stromboli volcano, Italy. The eruption occurred in a period of increased volcanic activity, following a first explosion in December 2002, which interrupted the typical moderate “Strombolian” behaviour. We present an exhaustive analysis of the available broadband seismic data and relate them to the observed eruption phases. Prominent features of the seismic signals include an ultra long period signal starting a few tens of seconds prior to the explosive eruption as well as a strong energetic signal a few seconds after the onset of the eruption. Both signals are not exactly synchronized with the other geophysical observations. We present a detailed study of those signals using spectral and particle motion techniques. We estimate eruption parameters and seismic source characteristics by different inversion approaches. Results clearly indicate that the paroxysmal eruption was triggered by a shallow slow thrust-faulting dislocation event with a moment magnitude of Mw=3.0 and possibly associated with a crack that formed previously by dike extrusion. At least one blow-out phase during the paroxysmal explosion could be identified from seismic signals with an equivalent moment magnitude of Mw=3.7 and is represented by a vertical linear vector dipole and two weaker horizontal linear dipoles in opposite direction, plus a vertical force.
    Description: Published
    Description: 164-178
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; source inversion ; volcano seismology ; paroxysm ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2017-04-04
    Description: This paper deals with the problem of seismicity at Mt. Vesuvius with a view to providing an estimation of the maximum expected earthquake. Integrated analysis of both historical and current seismicity as well as the geological conditions of Vesuvius and the surrounding areas show that seismogenetic structures may fall within the crater axis and at the boundaries of the volcanic complex. While activation of the whole seismogenetic volume detected by seismicity in the past 30 years would indicate a total seismic moment of Mo = 7.1E+ 15 Nm for a magnitude M = 4.5, knowledge of the area's geological structure suggests faulting surfaces of about 32 km2 with an associated magnitude of M = 5.4. The areas of maximum expected damage differ according to the orientation of the hypothesized structure. Analysis of geological and geophysical data and the damage associated to the AD 62 earthquake shows that the prevailing directions in the faulting planes are NE–SW in the eastern sector of the volcanic complex, and roughly WNW–ESE in the southern part of the volcano along the coast. Comparison of instrumental seismicity and historical data reveals two significantly different energy levels: a lower earthquake level with Mmax = 4.5, corresponding to current seismicity and that which accompanied volcanic activity in the eruptive period from 1631–1944; an upper level with Mmax = 5.4, represented by the AD 62 earthquake. The two levels correspond to two stress states and different seismogenetic structures.
    Description: Published
    Description: 139-149
    Description: 3.6. Fisica del vulcanismo
    Description: 3.10. Sismologia storica e archeosismologia
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 5.1. TTC - Banche dati e metodi macrosismici
    Description: JCR Journal
    Description: reserved
    Keywords: Mt. Vesuvius ; seismic hazard ; historical seismicity ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publication Date: 2017-04-04
    Description: Major and trace element and Sr–Nd–Hf–Pb isotopic data for the most primitive Tertiary lavas from the Veneto region (South-Eastern Alps, Italy) show the typical features of HIMU hotspot volcanism, variably diluted by a depleted asthenospheric mantle component (87Sr/86Sri=0.70306–0.70378; "Ndi=+3.9 to +6.8; "Hfi=+6.4 to +8.1, 206Pb/204Pbi=18.786–19.574). P-wave seismic tomography of the mantle below the Veneto region shows the presence of low-velocity anomalies at depth, which is consistent with possible upwellings of plume material. Between the depths of 100–250 km the velocity anomalies are approximately 2–2.5% slower than average, implying a temperature excess of about 220–280 K, in agreement with estimates for other mantle plumes in the world. In this context, the Veneto volcanics may represent the shallow expression of a mantle upflow. The presence of a HIMU-DM component in a collision environment has significant geodynamic implications. Slab detachment and ensuing rise of deep mantle material into the lithospheric gap is proposed to be a viable mechanism of hotspot magmatism in a subduction zone setting.
    Description: Published
    Description: 563–590
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: trace-element ; isotopic composition ; alkali basalts ; central-Europe ; slab break-off ; plume ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
    Publication Date: 2017-04-04
    Description: One of the most challenging issues about the Tertiary–Quaternary alkaline magmatism spreading across the Euro-Mediterranean region is the assessment of both the nature of its mantle source and the mechanism responsible for the common HIMU-like (High μ=high 238U/204Pb) character of erupted lavas, enduring over about 100 million years in diverse tectonic environments. In this paper we try to reconcile geochemical and geophysical data through a multidisciplinary investigation on geochemistry, timing and locations of the main Na-rich alkaline volcanic centers, seismic tomographic images and plate kinematics. We propose that the common component of the Euro-Mediterranean mantle derives from a contamination episode triggered by the rise of the Central Atlantic Plume (CAP) head. Plate reconstruction shows that at late Cretaceous- Paleocene time the oldest magmatic centers of the Euro-Mediterranean region were located more than 2000 km SW of their present day position, in proximity of the CAP hot spot location, where seismic tomography detects a broad low seismic velocity region in the lower mantle. The northeastward migration of the Eurasian and African plates could have involved also part of the CAP contaminated mantle, which moved in the same direction being coupled to the lithospheric plates, thus explaining the presence of geochemically-uniform material spread in the sub-lithospheric Euro-Mediterranean mantle. During the Tertiary, regional-scale convection and related processes such as rifting, back-arc spreading, slab detachment/windows, may have favored upwelling and partial melting of the frayed plume head material via adiabatic decompression, shaping the spatial and temporal distribution of HIMU-like volcanics. The growing supply of subducted lithosphere may explain as well the increase of crustal isotopic signatures of alkaline magmas with time. In our opinion, the Euro-Mediterranean upper mantle contamination can be eventually related to a global event occurred during the Cretaceous as a consequence of a mantle avalanche caused by the Tethys closure.
    Description: MIUR 2005-2007, prot. n. 2005055415_002, Poli G.
    Description: Published
    Description: 15–27
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: partially_open
    Keywords: Cenozoic HIMU–OIB volcanism ; Euro-Mediterranean mantle ; geochemistry ; mantle tomography ; plate kinematics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 14
    Publication Date: 2017-04-04
    Description: The controversial relationship between the orogenic segments of the Western Alps and the Northern Apennines is here explored integrating recently published 3D tomographic models of subduction with new and re-interpreted geological observations from the eclogitic domain of the Voltri Massif (Ligurian Alps, Italy), where the two belts joint each other. The Voltri Massif is here described as an extensional domain accommodating the opposing outward migration of the Alpine and Apennine thrust fronts, since about 30–35 Ma. Using tomographic images of the upper mantle and paleotectonic reconstructions, we propose that this extensional setting represents the surface manifestation of an along strike change in polarity of the subducted oceanic slab whose polarity changed laterally in space and in time. Our tectonic model suggests that the westward shift of the Alpine thrust front from the Oligocene onward was the consequence of the toroidal asthenospheric flow induced by the retreat of the Apenninic slab.
    Description: Published
    Description: 34–50
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Western Alps ; Northern Apennines ; Voltri Massif ; Tomography ; Kinematic reconstruction ; Extensional detachment ; Toroidal flow ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
    Publication Date: 2017-04-04
    Description: We report on new paleomagnetic results obtained from 27 sites sampled in the Plio-Pleistocene sequences at the external front of the central-northern Apennines. Previous analyses of Miocene (Messinian) sediments indicated that the present shape of the northern Apenninic arc is due to the oroclinal bending of an originally straight belt oriented around N320° and that vertical axis rotations accompanied the migration of the thrust fronts toward the Adriatic foreland [F. Speranza et al., J. Geophys. Res. 102 (1997) 3153-3166]. We tried to provide new paleomagnetic constraints for the timing and rates of the oroclinal bending process during the Pliocene and the Pleistocene. The results suggest that CCW rotations observed in the northern part of the studied area are possibly younger than 3 Ma. No regional rotation is recorded in the Pliocene and Pleistocene sediments from the southern part of the study area, analogously to the Messinian sediments of the 'Acquasanta' domain of Speranza et al. [F. Speranza et al., J. Geophys. Res. 102 (1997) 3153-3166]. A local significant CCW rotation (23° ± 10°) is identified in the Early Pleistocene sediments that crop out along the Adriatic coast between Ascoli and Pescara, indicating differential motion of the thrust sheets. This rotation must be younger than 1.43 Ma.
    Description: Published
    Description: 243-257
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: open
    Keywords: paleomagnetism ; Apennines ; tectonics ; Pliocene ; Pleistocene ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 16
    Publication Date: 2017-04-04
    Description: In this paper we present a collection of good quality shear wave splitting measurements in Southern Italy. In addition to a large amount of previous splitting measurements, we present new data from 15 teleseisms recorded from 2003 to 2006 at the 40 stations of the CAT/SCAN temporary network. These new measurements provide additional constraints on the anisotropic behaviour of the study region and better define the fast directions in the southern part of the Apulian Platform. For our analysis we have selected wellrecorded SKS phases and we have used the method of Silver and Chan to obtain the splitting parameters: the azimuth of the fast polarized shear wave (φ) and delay time (δt). Shear wave splitting results reveal the presence of a strong seismic anisotropy in the subduction system below the region. Three different geological and geodynamic regions are characterized by different anisotropic parameters. The Calabrian Arc domain has fast directions oriented NNE–SSW and the Southern Apennines domain has fast directions oriented NNW–SSE. This rotation of fast axes, following the arcuate shape of the slab, is marked by a lack of resolved measurements which occurs at the transition zone between those two domains. The third domain is identified in the Apulian Platform: here fast directions are oriented almost N–S in the northern part and NNE–SSW to ENE–WSW in the southern one. The large number of splitting parameters evaluated for events coming from different back-azimuth allows us to hypothesize the presence of a depth-dependent anisotropic structure which should be more complicated than a simple 2 layer model below the Southern Apennines and the Calabrian Arc domains and to constrain at 50 km depth the upper limit of the anisotropic layer, at least at the edge of Southern Apennines and Apulian Platform. We interpret the variability in fast directions as related to the fragmented subduction system in the mantle of this region. The trench-parallel φ observed in Calabrian Arc and in Southern Apennines has its main source in the asthenospheric flow below the slab likely due to the pressure induced by the retrograde motion of the slab itself. The pattern of φ in the Apulian Platform does not appear to be the direct result of the rollback motion of the slab, whose influence is limited to about 100 km from the slab. The anisotropy in the Apulian Platform may be related to an asthenospheric flow deflected by the complicated structure of the Adriatic microplate or may also be explained as frozen-in lithospheric anisotropy.
    Description: Published
    Description: 49-67
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: partially_open
    Keywords: Shear wave splitting ; Subduction ; Mantle flow ; Southern Italy ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes
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  • 17
    Publication Date: 2017-04-04
    Description: Historical sources have recorded earthquake shocks, their effects and difficulties that local inhabitants experienced before the AD 79 Pompeii eruption. Archaeological studies pointed out the effects of such seismicity, and have also evidenced that several water crises were occurring at Pompeii in that period. Indeed numerous sources show that, at the time of eruption, and probably some time before, the civic aqueduct, having ceased to be supplied by the regional one, was out of order and that a new one was being built. Since Roman aqueducts were usually built with a recommended minimum mean slope of 20 cm/km and Pompeii's aqueduct sloped from the nearby Apennines toward the town, this slope could have been easily cancelled by uplift that occurred in the area even if this was only moderate. For the crustal deformations a volcanic origin is proposed and a point source model is used to explain the observations. Simple analysis of the available data suggests that the ground deformations were caused by a b2 km3 volumetric change at a depth of ∼8 km that happened over the course of several decades.
    Description: Published
    Description: 959–970
    Description: 5.1. TTC - Banche dati e metodi macrosismici
    Description: JCR Journal
    Description: reserved
    Keywords: Vesuvius ; ground deformation ; seismicity ; stress changes ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 18
    Publication Date: 2017-04-04
    Description: In a geothermal area, a detailed knowledge of the three-dimensional velocity structures aids the managementof the field and the further development of the geothermal source. Here,we present a high-resolution study of the three-dimensional S-wave velocity structures from microearthquake travel times for the Larderello-Travale geothermal field, Italy.We have also deduced the Vp/Vs and Vp ×Vs parameters for this area toemphasize the deep variations in the physical rock properties due to fluid content and porosity. Furthermore, effective porousmedium modelling has been performed for site-relevant lithologies, to improve our interpretation of the results in terms of rock physics signatures. This has allowed us to estimate the variation range of the seismological parameters investigated, as well as their sensitivity for suitable rock under specific physical conditions. LowVp/Vs anomalies, arising froma lower Vp compared to Vs, dominate the geothermal field of Larderello-Travale. These have been interpreted as due to steam-bearing formations. On the contrary, analysis of Vp ×Vs images provides information on the relative changes in rock porosity at depth. Comparison of tomographic section images with previously interpreted seismic lines suggests that the reflective ‘K-horizon’ delineates a transition between zones that have different porosities or crack gatherings. The ‘K-horizon’ also lies on low Vp/Vs anomalies, which suggests a steam saturation zone, despite the reduced porosity at this depth.
    Description: In press
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: open
    Keywords: P- and S-wave velocity ; Seismic tomography images ; Geothermal field ; Rock properties ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 19
    Publication Date: 2017-04-04
    Description: We investigate the relationship between changes of the gravity field and the release of the seismic energy at Mt. Etna over a 12-year period (1994-2006), during which the volcano exhibited different eruptive patterns. Over the two sub-periods when intense gravity decreases occur, centered on the upper southeastern sector of the volcano (late-1996 to mid-1999 and late-2000 to mid-2001), the strain release curve displays neat long-term accelerations, with many hypocenters clustered in the volume containing the gravity source. Various evidences suggest that, since 1994 and until the breakout of the 2001 eruption, the eastern flank of Etna remained peripheral to the lines of rise of the magma from the deep storage to the surface. Accordingly, we hypothesize that, rather than being directly associated to the migration of the magma, the joint anomalies we found image phases of higher tensile stress on the upper southeastern sector, associated to increase in the rate of microfracturing along the NNW-SSE fracture zone. Such an increase implies a local density (gravity) decrease, and an increase in the release of seismic energy, thus explaining the correlation we observe. The second period of gravity decrease/strain release increase culminated in the breakout of the 2001 flank eruption, as a pressurized deeper magma accumulation used the inferred zone of increasing microfracturing as a path to the surface. This eruption marks an important modification in the structure of Etna’s plumbing system, as also testified by the absence of post-2001 long-term gravity changes and accelerations in the strain release curve and the neat modification of the seismicity and ground deformation patterns. Thus we prove that joint microgravity and seismic studies can allow zones of the medium experiencing an increase in the rate of microfracturing to be identified months to years before a magma batch is conveyed through them to the surface, setting off a lateral eruption.
    Description: Published
    Description: 282–292
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: microgravity changes ; seismic strain release ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 20
    Publication Date: 2017-04-04
    Description: An edited version of this paper was published by AGU. Copyright (2009) American Geophysical Union.
    Description: On multi-vents volcanoes changes in activity between different vents reflect a complex fluid-dynamics of the shallow feeding systems and are often explained numerically and experimentally in terms of conduit branches and bifurcations. We present new geophysical constraints on the shallow feeding system of Etna volcano derived from array analysis of infrasound radiated from two distinct sources, one located in the SE crater and one in the Voragine or NE crater (VNE). These two sources alternated in their behavior, with the VNE crater system radiating low amplitude background infrasound interrupted by episodes of increased infrasound radiation from the SE crater. This switching behavior suggested a branched shallow feeding system strongly controlled by the gas/magma-flux. Here, the VNE craters represented the preferential and most stable branch of degassing during stationary flux regime, while the SE crater branch activated in response to an increase in the magma/gas supply rate.
    Description: INGV-DPC V3 for the years 2005– 2007
    Description: Published
    Description: L19308
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Infrasound ; Mt. Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 21
    Publication Date: 2017-04-04
    Description: To recognize possible signals of intrusive processes leading to the last 2002–2003 flank eruption at Mt. Etna, we analyzed the spatial pattern of microseismicity between August 2001 and October 2002 and calculated 23 fault plane solutions (FPSs) for shocks with magnitude greater than 2.5. By applying the double-difference approach of Waldhauser and Ellsworth [2000] on 3D locations, we found that most of the scattered epicentral locations further collapse in roughly linear features. High-precision locations evidenced a distribution of earthquakes along two main alignments, oriented NE-SW to ENE-WSW and NW-SE, matching well both with the known tectonic and volcanic lineaments of Etna and FPSs results. Moreover, microseismicity and swarms located along the NNW-SSE volcano-genetic trend suggest, together with geodetic data and volcanological evidence that progressive magma refilling has occurred since February 2002.
    Description: Published
    Description: 1-4
    Description: partially_open
    Keywords: Seismology: Earthquake dynamics and mechanics ; Seismology: Earthquake parameters ; Seismology: Volcano seismology ; Volcanology: Eruption monitoring ; Volcanology: Magma migration. ; 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::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 22
    Publication Date: 2017-04-04
    Description: On July 18, 2001, two main eruptive vents opened on the southern flank of Mount Etna volcano (Italy) at ~2100 m and ~2550 m a.s.l., respectively. The former vent fed mild strombolian activity and lava flows, while the latter represented the main explosive vent, producing strong phreato-magmatic explosions. Explosions at this latter vent, however, shifted to a strombolian style in the following days, before switching back to phreato-magmatic activity towards the end of the eruption, which ended on August 9, 2001. On August 3, a small seismoacoustic array was deployed close to the eruptive vents. The array was composed of three stations, which recorded seismic and infrasonic waves coming from both of the eruptive vents. A further seismoacoustic station, equipped with a thermal-infrared sensor, was also installed several kilometers north of the first array. Seismic signals relating to the strombolian activity at the 2100-m vent were characterized by a strong decompression at the source. Analysis of the time delays between seismic, infrasonic and infrared event onsets also revealed that ejection velocities during explosions from both vents were subsonic. Time delays between the onset of explosive events apparent in the infrared and infrasound data indicated that the explosion source at the 2550-m vent was located 220–250 m below the crater rim. In comparison, the depth of the seismic source was estimated to be between 230 and 335 m below the rim. This converts to 120–150 and 130–235 m below the preexisting ground surface. In addition, time delays between seismic and infrasonic signals recorded for the lower (2100 m) vent also revealed a seismic source that was no more than a few tens of meters deeper than the fragmentation surface.
    Description: Published
    Description: 219-230
    Description: partially_open
    Keywords: Mt. Etna ; explosive eruptions ; arrays ; seismic ; infrasonic and thermal data ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 23
    Publication Date: 2017-04-04
    Description: Soil radon emissions have been proved as a useful tool for predicting earthquakes and volcanic eruptions and furthermore aided in determining the location of active faults. Continuous radon monitoring was carried out near Southeast Crater of Mt. Etna in September–November 1998, during a period of frequent eruptive episodes at that crater. Radon anomalies were detected when eruptive episodes and the accompanying volcanic tremor became increasingly intense: no anomalies in radon activity were observed during the first five, and weaker, eruptive episodes, whereas significant spikes in radon activity preceded the latter five episodes by ≥46 hours. This probably reflects increased gas leakage through fractures intersecting the shallow plumbing system, as gas pressure in the Southeast Crater conduit became higher with time. Radon monitoring thus might serve to better understand eruptive mechanisms and possible precursors, making further studies in this field a promising perspective.
    Description: Published
    Description: 1-4
    Description: partially_open
    Keywords: Seismology: Volcano seismology ; Structural Geology: Role of fluids ; Volcanology: Volcano monitoring ; Volcanology: Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 24
    Publication Date: 2017-04-04
    Description: The Tyrrhenian Sea is an extensional basin opened by trench retreat and back-arc extension during subduction of the Calabrian slab in the last 10–12 My. Subduction is still active beneath the SEmost part of the Tyrrhenian Sea, as testified by seismicity down to 500 km depth. By analyzing seismicity and geodetic data, together with recent tomographic images, we define the present-day situation. An evident N-S compressional regime prevails in the Tyrrhenian region west of the Aeolian archipelago, while east of them a NNW-SSE extension is documented by focal mechanisms and GPS data, with a much smaller strain rate with respect to the past. The transition between these two domains is accommodated by a N-S discontinuity zone which runs from Aeolian Islands to Mt. Etna with an extensional to strike-slip deformation.
    Description: Published
    Description: L06611
    Description: JCR Journal
    Description: reserved
    Keywords: geodynamics ; seismotectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 25
    Publication Date: 2017-04-04
    Description: The Lower Paleozoic assemblages in the E. Meditterranean comprise a Southern (Tauride-Anatolide,SE Anatolia and Central Iranian terranes) and a Northern (Carpathian-Balkan, Istanbul, Zonguldak and the Main Range terranes) Zone. A detailed stratigrapic account is given for these terranes for the Early Paleozoic and their paleogeographical settings are discussed to evaluate the Early Paleozoic geodynamic interpretation of this critical area between Gondwana-Perigondwana and Laurussia..
    Description: Published
    Description: 315-323
    Description: JCR Journal
    Description: open
    Keywords: Palaeozoic, evolution, Turkey ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 26
    Publication Date: 2017-04-04
    Description: Seismic attenuation in the area of Mt. Vesuvius is reappraised by studying more than 400 S-coda envelopes of small local VT earthquakes recorded at Mt. Vesuvius from 1996 to 2002 at the three-component stations of OVO and BKE. The purpose is to obtain a stable separate estimate of intrinsic and scattering quality factors for shear waves. We investigate in the present paper four frequency bands, centered respectively at fc = 3, 6, 12 and 18 Hz with a bandwidth of 0.6fc. Stacked coda envelopes are fit to the multiple scattering model according to the Zeng approximation in the hypothesis of constant velocity half space. Results show that the diffusion regime is a good approximation as the scattering attenuation (proportional toQ−1 S , the inverse scattering-quality factor) is much stronger than the intrinsic dissipation (proportional to Q−1 I ). Q−1 S decreases with frequency while intrinsic attenuation is much less frequency-dependent. We also fit the stacked coda envelopes at BKE to the diffusion equation solved with the boundary condition of a 2 km thick diffusive layer over a homogeneous half space. Results show that the diffusivity, D, estimated in the assumption of reflecting boundary condition is greater than that estimated in the assumption of uniform half space, whereas the diffusivity estimated with the absorbing boundary condition is close to the estimate done in the assumption of half space. OVO station shows results different from those obtained at BKE and at a group of five stations located on Mt. Vesuvius for the frequency bands centered at 12 and 18 Hz. In these two bands, scattering attenuation at OVO is comparable to the intrinsic dissipation, and is much smaller than that measured at the other stations. We interpret this anomaly as due to an effect of strong lateral heterogeneity which modifies the redistribution of the seismic energy into the coda at OVO. A comparison of the results obtained using passive data (the present data set) and the active data obtained in the same area during TOMOVES experiment by Wegler (2004) show that the diffusivity estimated with shot data during TOMOVES is smaller of a factor greater than 4. This discrepancy is interpreted as due to different earth volumes sampled by the coda waves in the two cases.
    Description: Published
    Description: 202-212
    Description: reserved
    Keywords: Scattering ; Diffusion ; Seismic attenuation ; Mt. Vesuvius ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 27
    Publication Date: 2017-04-04
    Description: The seismicity which affects Mt.Vesuvius is, at present, the only clear indicator of the volcano dynamics. In the last years, two periods of increased seismic activity occurred (August-October 1995 and March-May 1996). This seismicity was detected by the 10 analog stations of the Permanent Seismic Network as well as by up to 7 three-component temporary digital stations. A total number of about 600 events have been recorded, four of which showing magnitude 〉3.0. The maximum magnitude earthquake (M=3.4) was the strongest in the last fifty years and occurred on 25 April 1996. The use of three-component seismometers allowed us to obtain very reliable hypocentral locations. The focal volume of the two seismic crises does not exceed 5-6 km of depth below the crater area. Fault plane solutions of the most energetic events show focal planes oriented NW-SE and NE-SW, in agreement with the regional tectonic features, indicating that at present the seismicity of Mt.Vesuvius develops along pre-existing discontinuities. In addition, the occurrence of a fluiddriven source mechanism suggests a role played by the underground water on the seismic energy release. Shear wave splitting analyses confirmed the presence of an anisotropic volume related to a distribution of cracks andlor fractures parallely aligned to the main faults system of the volcano.
    Description: Published
    Description: 977-983
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Mt. Vesuvius ; seismic swarms ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 28
    Publication Date: 2017-04-04
    Description: Surface waves from the great Sumatra-Andaman earthquakes of 2004 and 2005 that cross Italy south of 44 N display Love-to-Rayleigh scattered waves (quasi- Love phases) diagnostic of sharp lateral gradients in the anisotropic properties of Earth’s upper mantle. Surface waves that traverse Italy further north lack this distinctive phase, documenting a change in the upper mantle fabric that is corroborated by a shift in the fast polarization of shear wave birefringence. These observations suggest that orogen-parallel asthenospheric extension behind the retreating Apennines slab has limited geographical expression. We hypothesize that subduction rollback currently terminates at 44 N, while the upper mantle flow pattern further to the north has been recently rearranged.
    Description: Published
    Description: L04304
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: surface wave ; Sumatra earthquake ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 29
    Publication Date: 2017-04-04
    Description: Two swarms of microearthquakes (ML ≤ 2.2), occurred on July 2-7 and August 22, 2000 at Campi Flegrei, accompained by a ground uplift episode (4 cm) which interrupted on early March 2000 the descending trend started on 1985. Spectral analysis indicates a direct involvement of magmatic/hydrothermal fluids in the source process of the July swarm, while the August events are typical of shear failure, similar to most of the earthquakes that occurred during the last (1982-1984) bradyseismic crisis. Precise 3-D relative location applied to similar earthquakes allows for the recognition of two parallel alignments trending NE-SW at depths of 1.7 and 3.2 Km. This trend is consistent with the direction of the main focal plane obtained from fault plane solutions and evidences tensile failure in close proximity to the zone of maximum uplift as depicted by geodetic measurements. A fault weakening mechanism triggered by increasing pore pressure is invoked as the cause of these earthquakes.
    Description: Published
    Description: 2525-2528
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Campi Flegrei ; seismic swarm ; earthquakes locations ; 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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  • 30
    Publication Date: 2017-04-04
    Description: Following the installation of a broadband network on Mt. Etna, sustained Long-Period (LP) activity was recorded accompanying a period of total quiescence and the subsequent onset of the 2004–2005 effusive episode. From about 56000 events detected by an automatic classification procedure, we analyse a subset of about 3000 signals spanning the December 17th, 2003–September 25th, 2004, time interval. LP spectra are characterised by several, unevenly-spaced narrow peaks spanning the 0.5–10 Hz frequency band. These peaks are common to all the recording sites of the network, and different from those associated with tremor signals. Throughout the analysed time interval, LP spectra and waveforms maintain significant similarity, thus indicating the involvement of a non-destructive source process that we interpret in terms of the resonance of a fluid-filled buried cavity. Polarisation analysis indicates radiation from a non-isotropic source involving large amounts of shear. Concurrently with LP signals, recordings from the summit station also depict Very-Long-Period (VLP) pulses whose rectilinear motion points to a region located beneath the summit craters at depths ranging between 800 and 1100 m beneath the surface. Based on a refined repicking of similar waveforms, we obtain robust locations for a selected subset of the most energetic LP events from probabilistic inversion of travel-times calculated for a 3D heterogenous structure. LP sources cluster in a narrow volume located beneath the summit craters, and extending to a maximum depth of ≈ 800 m beneath the surface. No causal relationships are observed between LP, VLP and tremor activities and the onset of the 2004–2005 lava effusions, thus indicating that magmatic overpressure played a limited role in triggering this eruption. These data represent the very first observation of LP and VLP activity at Etna during non-eruptive periods, and open the way to the quantitative modelling of the geometry and dynamics of the shallow plumbing system.
    Description: Published
    Description: 340-354
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: long-period seismicity ; Etna volcano ; volcano monitoring ; precursor ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 31
    Publication Date: 2017-04-04
    Description: We provide new data on relative sea-level change from the late Holocene for two locations in the central Mediterranean: Sardinia and NE Adriatico. They are based on precise measures of submerged archaeological and tide notch markers that are good indicators of past sea-level elevation. Twelve submerged archaeological sites were studied: six, aged between 2.5 and 1.6 ka BP, located along the Sardinia coast, and a further six, dated 2.0 ka BP, located along the NE Adriatic coast (Italy, Slovenia and Croatia). For Sardinia, we also use beach rock and core data that can be related to Holocene sea level. The elevations of selected significant archaeological markers were measured with respect to the present sea level, applying corrections for tide and atmospheric pressure values at the time of surveys. The interpretation of the functional heights related to sea level at the time of their construction provides data on the relative changes between land and sea; these data are compared with predictions derived from a new glacio–hydro-isostatic model associated with the Last Glacial cycle. Sardinia is tectonically relatively stable and we use the sea-level data from this island to calibrate our models for eustatic and glacio–hydro-isostatic change. The results are consistent with those from another tectonically stable site, the Versilia Plain of Italy. The northeast Adriatic (Italy, Slovenia and Croatia) is an area of subsidence and we use the calibrated model results to separate out the isostatic from the tectonic contributions. This indicates that the Adriatic coast from the Gulf of Trieste to the southern end of Istria has Q1 tectonically subsided by 1.5m since Roman times.
    Description: Published
    Description: 2463-2486
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: sea level, archaeology, tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 32
    Publication Date: 2017-04-04
    Description: We report on the paleomagnetism of 34 sites from lower Oligocene–middle Miocene sediments exposed in the Tertiary Piedmont Basin (TPB, northern Italy). The TPB is formed by a thick (4000 m) and virtually undeformed sedimentary succession unconformably lying upon Alpine nappes decapitated by extensional exhumation, which in turn are tectonically stacked over the Adriatic foreland. Paleomagnetic directions from 23 (mostly Oligocene) sites were chronologically framed using new biostratigraphic evidence from calcareous nannoplankton. Our data, along with published paleomagnetic results, show that the TPB rotated 50 counterclockwise with respect to Africa in Aquitanian-Serravallian times. The rotation was likely driven by underneath nappe stacking and was synchronous with (further) bending of the Alpine chain. Both the rotation magnitude and its timing are similar to those documented for the Corsica-Sardinia microplate. Therefore the formation of the western Alpine arc (or at least part of its present-day curvature) occurred during the rollback of the Apenninic slab and related back-arc spreading of the Liguro-Provenc¸al Basin and drift of the Corsica-Sardinia block. This suggests a common dynamics driving both the Alpine and the Apennine slab motions. Paleomagnetic data also document that the Adriatic plate has undergone no paleomagnetic rotation since mid-late Miocene times. Anisotropy of magnetic susceptibility data suggests that the TPB, an enigmatic basin arising from a controversial tectonic setting, formed in an extensional regime characterized by a stretching direction approximately orthogonal to the main trend of the underlying chain.
    Description: Published
    Description: B03104
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Paleomagnetism ; Tertiary Piedmont Basin ; Paleomagnetic directions ; Biostratigraphic evidence ; 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
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  • 33
    Publication Date: 2017-04-04
    Description: Many of the mountain belts displaying a curved shape are "oroclines", i.e. are produced after progressive bending of an originally straight fold and thrust belt. The bending process was previously explained as a consequence of several possible events taking place in the crustal orogenic wedge, such as occurrence of obstacles, non-coaxial deformation, and mouvements on wrench faults. Recent paleomagnetic results from the northern Apenninic Arc document that this belt is properly an orocline and results from Late Messinian-Early Pliocene bending of a Messinian straight belt-foredeep system. Tomographic images in turn show the presence of a high-velocity body, interpreted as subducted slab, in the upper mantle beneath the northern Apennines, between 35 and 670 km depth. Down to 100 km, this body displays an arcuate shape which closely mirrors the geological outlines, while it appears to be straight (and parallel to the Messinian pre-rotated belt) at depth. We explore here the possibility that the arcuate shape of the northern Apennines is a consequence, closely following in time, on much deeper processes than previously suggested, i.e. the lateral bending of the subducting Adriatic plate.
    Description: Published
    Description: 53-64
    Description: JCR Journal
    Description: reserved
    Keywords: paleomagnetism ; seismic tomography ; Northern Apennines ; orocline ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 34
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    Unknown
    AGU
    In:  Reply to Comment on “Could the Mw = 9.3 Sumatra Earthquake Trigger a Geomagnetic Jerk?”
    Publication Date: 2017-04-04
    Description: We thank M. Dumberry for providing the opportunity to discuss further the article [Florindo et al., 2005] in which we suggested that the Sumatra earthquake could have triggered a geomagnetic jerk. Dumberry is against our hypothesis for different reasons: (1) The displacement pattern produced by this earthquake is incompatible with the core-mantle boundary (CMB) deformations required for a torsional oscillation; (2) most of the deformations occurred locally, producing an actual mass displacement that has not involved the entire Earth; and (3) no abrupt change in the length of day (LOD) has been observed after this event. Although we agree with some of the considerations proposed by Dumberry, we think that these do not rule out the possibility that a jerk has been triggered by the Sumatra earthquake or that in the future, other earthquakes could induce a change in the flow pattern near the CMB leading to a geomagnetic jerk. On the contrary, we retain that this hypothesis is plausible, although it is more correct to talk about the existence of a possible link between geomagnetic jerks and earthquakes where the earthquake magnitude is not the only discriminating parameter.
    Description: Published
    Description: 343
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: 3.4. Geomagnetismo
    Description: N/A or not JCR
    Description: reserved
    Keywords: Sumatra Earthquake ; Geomagnetic Jerk ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 35
    Publication Date: 2017-04-04
    Description: The 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamic of the volcano, marking the passage from a period (March 1993 – June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveal a southward motion of the upper southern part of the volcano, driven by a NNW-SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: Stress release ; Dike ; Volcano-tectonics ; Flank instability ; Mount Etna ; Instrumental monitoring ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.06. 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::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. 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::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 36
    Publication Date: 2017-04-04
    Description: A fundamental goal of volcano seismology is to understand the dynamics of active magmatic systems in order to assess eruptive behavior and the associated hazard. Imaging of magma conduits, quantification of magma transport and investigation of long-period seismic sources, together with their temporal variations, are crucial for the comprehension of eruption-triggering mechanisms. At Mt. Etna volcano, several intense episodes of tremor activity were recorded during 2007, in association with strombolian activity and/or intense fire fountaining episodes occurring from the South East Crater (SEC). The locations of the tremor sources and of the long-period seismic events are used here to constrain both the area and the depth range of magma degassing, highlighting the geometry of the shallow conduits feeding SEC. The imaged conduits consist of two connected resonating dike-like bodies, NNW-SSE and NW-SE oriented, extending from sea level to the surface. In addition, we show how tremor, long-period (LP) and very-long-period (VLP) event locations and signatures reflect pressure fluctuations in the plumbing system associated with the ascent/discharge of gas-rich magma linked to the lava fountains. The evidence here reported, also corroborated by ground deformation variations, can help develop a better prediction and early-warning system for those eruptions (effusive or explosive) that apparently manifest no clear precursors.
    Description: Supported by grants from the European Union VOLUME FP6-2004-Global-3
    Description: Published
    Description: Q12021
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: open
    Keywords: volcano plumbing system ; volcanic tremor ; LP and VLP events ; Mt. Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 37
    Publication Date: 2017-04-04
    Description: Shield volcanoes, caldera-bearing stratovolcanoes, and monogenetic cones compose the large fissural Payen Volcanic Complex, located in the Andes foreland between latitude 35°S and 38°S. The late Pliocene-Pleistocene and recent volcanic activity along E-W trending eruptive fissures produced basaltic lavas showing a within-plate geochemical signature. The spatial distribution of fractures and monogenetic vents is characterized by self-similar clustering with well defined power law distributions. Vents have average spacing of 1.27 km and fractal exponent D = 1.33 defined in the range 0.7–49.3 km. The fractal exponent of fractures is 1.62 in the range 1.5–48.1 km. The upper cutoffs of fractures and vent fractal distributions (about 48–49 km) scale to the crustal thickness in the area, as derived from geophysical data. This analysis determines fractured media (crust) thickness associated with basaltic retroarc eruptions. We propose that the Payen Volcanic Complex was and is still active under an E-W crustal shortening regime.
    Description: Published
    Description: Q09002
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic field ; crustal shortening ; vent distibution ; Andes ; Argentina ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 38
    Publication Date: 2017-04-04
    Description: This study presents a detailed analysis and interpretation of the seismicity that occurred on July 2-7 and August 22, 2000, during a ground uplift episode which started on March 2000 at Solfatara crater, Campi Flegrei. Earthquakes are located using a probabilistic grid-search procedure acting on a 3-D heterogeneous earth structure. The mainshock of the July swarm depicts a spectrum characterized by a few narrow peaks spanning the 1^5-Hz frequency band. For this event, we hypothesize a direct involvement of magmatic fluids in the source process. Conversely, the spectra of the August events are typical of shear failure. For these latter events, we evaluate the source properties from P-and Swave displacement spectra. Results for the most energetic shocks (Md around 2) yield a source radius in the order of 100 m and stress drop around 10 bars, in agreement with most of the earthquakes that occurred during the 1982-1984 bradyseismic crises. For the August swarm we identify two clusters of similar earthquakes. Application of highresolution relative location techniques to these events allows for the recognition of two parallel alignments trending NE^SW. The relationship among source dimension and relative location evidences overlapping of sources. This may be interpreted in terms of either a heterogeneous stress field or a lubrication process acting over the fault surface. For a selected subset of the August events, we also analyze the splitting of the shear waves: results are indicative of wave propagation through a densely fractured medium characterized by a distribution of cracks oriented NE-SW. The pattern of faulting suggested by relative locations and shear-wave splitting is not consistent with the surface trace of NW^SE striking faults. However, a detailed mesostructural analysis carried out over the Solfatara area indicated the occurrence of two main crack systems striking NW-SE and NE-SW. This latter system shows a strike consistent with that derived from seismic evidence. Results from a stress analysis of the crack systems indicate that a fluid overpressure within the NW-SE-striking faults is able to form NE-SW cracks. We found that the pressure of fluids Pf required to activate the NW-SE faults is less than cHmin, while the Pf value required to open the NE-SW cracks is higher than cHmax. Our main conclusions are: (a) the Solfatara area is affected by two orthogonal fracture systems, and the fluid pathway during the 2000 crisis mainly occurred along the NNE-SSW/NE-SW-striking crack system; (b) the July seismicity is associated to the upward migration of a pressure front triggered by an excess of fluid pressure from a small-size magmatic intrusion; conversely, the August events are associated to the brittle readjustment of the inflated system occurring along some lubricated structures.
    Description: Published
    Description: 229-246
    Description: partially_open
    Keywords: Seismicity ; Hydrothermal fuids ; Fuid pressure ; Faults ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 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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  • 39
    Publication Date: 2017-04-04
    Description: The understanding of shallow intrusive processes during 2002–2004, as well as the causes of the volcano-tectonic seismicity, has been improved at Mt. Etna by comparing the inversion results from GPS data with accurate 3D hypocentral locations. Our findings indicate that short periods of deflation (about six months) were followed by recharging phases after the end of both the 2001 and 2002–2003 flank eruptions. During the last recharging phase (June 2003–August 2004), modeling results and seismic observations suggest a composite mechanism of re-injection of magma into the rift-zones (S and NE), similar to that leading to the 2002–2003 flank eruption, which could have triggered the summit eruption started on September 7, 2004.
    Description: Published
    Description: 1-4
    Description: partially_open
    Keywords: Volcanology: Magma migration and fragmentation ; Seismology: Earthquake interaction, forecasting, and prediction ; Seismology: Seismicity and tectonics ; Volcanology: Volcano monitoring ; Volcanology: Eruption mechanisms and flow emplacement ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 40
    Publication Date: 2017-04-04
    Description: A selected dataset of 151 events, leading the July 17–August 9, 2001 lateral eruption at Mt. Etna volcano, has been analyzed for three-dimensional hypocenter locations, focal mechanisms and stress tensor inversions. The seismic pattern provided indications for two main spatial clusters of foci located along and eastwards of the 2001 Mt. Etna eruptive fractures system. The 151 fault plane solutions (mostly strike slip) were inverted for stress tensor parameters, and space variations of seismogenic stress orientations have been identified. The stress inversion results and the axi-symmetric orientation of P-axes, in the region surrounding the modeled dike, well support the evidence of a unique stress source in agreement with the ground deformation results.
    Description: Published
    Description: 1-4
    Description: partially_open
    Keywords: Seismology: Volcano seismology ; Volcanology: Eruption mechanisms ; Volcanology: Magma migration ; Volcanology: Eruption monitoring. ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 41
    Publication Date: 2017-04-04
    Description: Changes in Coulomb failure stress (ΔCFS) induced by dike propagation during two flank eruptions on Mt. Etna (1981 and 2001) are calculated for the most seismically active faults on the east slope of the volcano (the right-lateral Timpe fault system, oriented NNW-SSE, and the left-lateral Pernicana fault, oriented E-W). Calculations performed using Coulomb 2.5 software indicate that intrusion of a NNW dike on the NW side of the volcano (1981 eruption) rises ΔCFS on both the Timpe and Pernicana faults. In contrast, intrusion of a N-S dike at high elevation on the south flank (2001 eruption) rises ΔCFS only on Timpe fault System. These results are compatible with the observed pattern of seismicity, but emphasize an extremely heterogeneous state of stress on the east flank of the volcano.
    Description: Published
    Description: 1-4
    Description: partially_open
    Keywords: Seismology: Earthquake interaction, forecasting, and prediction ; Seismology: Volcano seismology ; Tectonophysics: Stresses: crust and lithosphere ; Volcanology: Magma migration and fragmentation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 42
    Publication Date: 2017-04-04
    Description: The seismic activity of Mt. Etna from April 1988 until the December 1991 eruption was monitored by means of permanent and temporary seismic network. Volcanic activity that occurred during this period was preceded and accompanied by the occurrence of deep (Z 〉/- 15 km) seismicity. This deep seismic activity, occurring a few days up to some weeks before the volcanic phases, was characterized by typical mainshock-aftershocks sequences. Both the observation of deep seismicity occurrence also before or during previous eruptions and the role played by tectonics as controller of the magma uprise suggest the hypothesis of a relation between the seismic energy released in the volcanic basement and the recharge mechanisms of the volcanic system.
    Description: Published
    Description: 277-289
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: deep earthquakes ; volcano ; Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 43
    Publication Date: 2017-04-04
    Description: We study the upper mantle P wave velocity structure below the Euro-Mediterranean area, down to 1000 km depth, by seismic travel time tomography. We invert summary residuals constructed with both regional and teleseismic first arrival data reported by the International Seismological Centre (ISC) (1964–1995), introducing some alternative strategies in the travel time tomographic approach and a new scheme to correct teleseismic data for global mantle structure. Our high-resolution model PM0.5 is parameterized with three-dimensional (3-D) linear splines on a grid of nodes with 0.5 spacing in both horizontal directions and 50 km vertical spacing. We obtain about 26% root-mean-square (RMS) reduction of residuals by inversion in addition to roughly 31% reduction after summary rays formation and selection. Sensitivity analyses are performed through several test inversions to explore the resolution characteristics of the model at different spatial scales. The distribution of large-scale fast anomalies suggests that two different stages of a convection process presently coexist in very close regions. The mantle dynamics of western central Europe is dominated by blockage of subducted slabs at the 660 km discontinuity and ponding of seismically fast material in the transition zone. Contrarily, in the eastern Mediterranean, fast velocity material sinks into the lower mantle, suggesting that the flow of the cold downwelling here is not blocked by the 660 km discontinuity. On a smaller scale, the existence of tears in the subducted slab (lithospheric detachment) all along both margins of the Adriatic plate, as proposed by some authors, is not supported by our tomographic images.
    Description: Published
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: travel time ; body wave tomography ; upper mantle ; Europe-Mediterranean area ; Earth structure ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 44
    Publication Date: 2017-04-04
    Description: Slab-like seismic velocity heterogeneities below the Alpine chain, interpreted as subducted lithosphere, are imaged by tomographic studies down to only about 300 km depth. A non-negligible discrepancy therefore exists between tomographic and geological data, the latter indicating at least 500 km of Tertiary convergence at trench. Yet a recently published tomographic study detects a pronounced high velocity anomaly at the bottom of the upper mantle right below the Alpine area. Combining tomographic images of the mantle, geological findings and plate system kinematics, we investigate how the presence of this feature in the transition zone below the Alps can be traced back to the Tertiary Alpine subduction and possibly explain the observed discrepancy. We propose that a part of the fast velocity body now residing just above the 660 km discontinuity once belonged to the Alpine slab, torn off by an event occurred at about 30–35 Ma.
    Description: Published
    Description: L06605
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Alps ; upper mantle ; tomography ; subduction ; break-off ; transition zone ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 45
    Publication Date: 2017-04-04
    Description: By means of a stratified viscoelastic Earth model we study the effect of sinking slabs on the dynamic topography, the non-hydrostatic geoid and the long-term sea level variations. Sea level fluctuations due to subduction are found to be sensitive to the nature of the 670 km seismic discontinuity and to the rheological layering of the mantle. The response of our model to both a single subduction and a realistic distribution of slabs is studied by a numerical simulation based on a simplified approach. Consistent with previous results, we find that an upper bound to relative sea level time variations associated with the initiation of a new subduction in the upper mantle is ∼0.1 mm/yr. Relative sea level changes driven by the dynamic readjustment of internal mass heterogeneities may thus be comparable with those attributed to other changes in the tectonic regime on a large scale. This confirms the relevance of subduction as an important contributor to long-term sea level fluctuations.
    Description: Published
    Description: 1587–1590
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: sea level ; geoid ; dynamic topography ; subduction ; viscosity profile ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 46
    Publication Date: 2017-04-04
    Description: We tie together geological data, paleotectonic reconstruction, plate motion, and tomographic analysis to unravel the history of subduction and back arc extension of the eastern and central Mediterranean. In these two regions, extensional processes started contemporaneously, around 30 Myr ago, but with marked differences. In the eastern region, the Aegean basin opened slowly ( 1 cm/yr) behind a shallow dipping slab (40–45 ). The corresponding high-velocity anomaly extends inside the upper mantle and can be also followed in the midmantle down to a depth of at least 1500 km. Its descent into the midmantle initiated most probably during the Late Cretaceous, and the trench moved northeastward, following the path of the Eurasian plate and under the persistent push of the African plate. Conversely, in the central Mediterranean region, subduction initiated later, and the motion of the subducting slab is confined to the upper mantle, causing punctuated and rapid episodes of back arc extension (Provenc¸al and Tyrrhenian basins) behind a slab that dips steeply (75 ). We explore the causes that control how the slab subducted and interacted with the lower, more viscous part of the mantle.
    Description: Published
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: subduction ; Mediterranean ; mantle convection ; back-arc extension ; plate motion ; seismic tomography ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 47
    Publication Date: 2017-04-04
    Description: During the December 2005-January 2006 non-eruptive period, the tremor amplitude at Etna markedly increased and negatively correlated with the gravity signal from one of the two summit station, over 2-3 hour periods. No correlation was found with the signal from the other gravity station. We locate the tremor source by inverting the spatial distribution of seismic amplitudes. Relying on the relative position of the two stations, we define a volume within which the gravity source must lie. During the period of marked anti-correlation, the tremor sources intersect this volume in a region located 1 km S-SE of the summit craters and about 2 km beneath the surface. This finding suggests that the anti-correlation marks the activation of a joint source process, possibly related to the arrival of fresh magma and the consequent gas separation. Our study has implications for the early recognition of gas segregation processes at active volcanoes.
    Description: Published
    Description: L06305
    Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic tremor ; Etna volcano ; gravity changes ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 48
    Publication Date: 2017-04-04
    Description: This paper presents the results of hydrogeochemical and seismological studies carried out at Mt. Vesuvius during the period June 1998 – December 2005. Hydrogeochemical data show the occurrence of slowly varying long-term variations in the total dissolved salts and bicarbonate contents of the groundwaters, accompanied by a general decline in water temperatures. The temporal distributions of air temperature and rainfall in the Vesuvius area suggest that these variations do not depend on changes in the hydrological regime. The changes in the geochemical parameters are accompanied by slight variations in both the seismicity rate and energy release. A further relationship between seismic activity and fluid discharge rate is highlighted by a particular episode that occurred in August 2005, when a soil thermal anomaly was observed a few weeks before the occurrence of a very shallow earthquake. Moment-tensor analysis of this earthquake suggests that the most plausible source mechanism is a shear faulting combined with the opening of tensile crack. This feature is often observed in volcanic areas and it is usually related to fluid-/gas-driven rock fracturing. The observed seismological, hydrological, and geochemical temporal changes are interpreted not as changes of the volcanic system, but in terms of an external forcing as identified in the variation of the regional and local stress field acting on the volcano. This study has inferences onto the evaluation of the state of activity of volcanic systems and the eventual detection of unrest phenomena.
    Description: Published
    Description: B05206
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Vesuvius ; seismicity ; fluid circulation ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 49
    Publication Date: 2017-04-04
    Description: We analyze the 1997–2006 seismicity of the transition zone between Southern and Central Apennines, which is one of the most active seismic areas of Italy. Our aim is to add information on the seismotectonic picture of this area. Seismic activity is characterized by single events with Mb3.0 and low magnitude (Mb4.0) seismic sequences (1997–98 and 2005) and swarms (1999, 2000 and 2001). Hypocenters are within the upper 15 km of the crust. The epicentral distribution of the relocated seismicity shows that single events prevalently align NW–SE along the Apennine chain axis. This seismicity is related to the main, NE–SW extension affecting the chain. Single events concentrate also: at the south of the seismogenetic source responsible for the 1915 earthquake, where the 2000 swarm occurred; between the faults of the 1984 and 1805 events, where the 2001 sequence developed; between the faults of the 1805 and 1688 events, where the 1997–1998 seismic sequence concentrated. The seismic swarms occurred in 1999, 2000 and 2005 are located inside the Ortona– Roccamonfina structural line, which strikes NNE–SSW and separates the Central Apennines from the Southern ones. The epicentral distribution of these swarms and focal mechanisms suggest the presence of active NE–SW faults moving in response to a NW–SE extension. The results of the strain analysis on 52 wellconstrained focal mechanisms evidence a prevailing NE–SW extension, corresponding to the large scale stress field acting in the Apennine Chain, and a second-order NW–SE extension. This last direction of extension was already observed in the 1997–98 and 2001 seismic sequences. The location of the NE–SW striking faults responsible for the seismic swarms suggest that some segments of the Ortona–Roccamonfina line are still active and move in response to both the NE–SW regional extension of Southern Apennines, and to a NW–SE striking longitudinal extension.
    Description: Published
    Description: 102-110
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    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: reserved
    Keywords: Apennines ; seismicity ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
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  • 50
    Publication Date: 2017-04-04
    Description: During local and regional earthquakes, an evident amplification of horizontal ground motion is observed at two seismological stations near the Tremestieri fault, on the southeastern flank of Mt. Etna volcano. Rotated-component spectral ratios show a narrow spectral peak around 4-Hz along a N40°E direction. A conventional polarization analysis using the eigenvectors of the covariance matrix confirms the very stable directional effect enhancing the approximately NE-SW elongation of the horizontal ground motion in the fault zone. The effect is evident during the entire seismogram and independent of source backazimuth as well as distance and depth of earthquakes. The same polarization is observed in ambient noise as well. This consistency allowed us to use microtremors for checking ground motion polarization along and across the Tremestieri fault zone with a high spatial resolution. The result is a stable polarization of horizontal motion in the entire area, interesting a broad frequency band. To check whether this ground motion property is recurrent and understand a possible relationship with fault strike, faulting style, or orientation of fractures, ambient noise was recorded on other mapped faults of the Mt. Etna area, the Moscarello, Acicatena and Pernicana faults. The latter, in particular, is characterized by different strike and faulting style. A systematic tendency of ambient noise to be polarized is found in all of the faults. A picture emerges where normal faults of the eastern flank show a E-W to NE-SW polarization that changes on the Pernicana fault, which develops approximately E-W and is characterized by a prevailing NW-SE to NS polarization. Directions of polarization were never parallel to the fault strike. Moreover, polarization persists too far away from the fault trace, excluding an effect limited to a narrow low velocity zone hosted between harder wall rocks. Both these observations rule out an interpretation in terms of fault-trapped waves. The cause of observed polarizations will be the subject of future studies. However, the consistency with recent results of velocity anisotropy in a part of the investigated area suggests a possible role of attenuation anisotropy on horizontal amplitude variations versus azimuth.
    Description: Published
    Description: B10306
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: polarization ; fault zones ; Etna volcano ; microtremors ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 51
    Publication Date: 2017-04-04
    Description: Five three-component broadband ocean bottom seismometers (OBSs) were deployed on the seafloor around the Aeolian Islands (Southern Tyrrhenian Sea). By comparing OBSs digital seismograms, we found a low-frequency seismicity recorded only at OBS05, the nearest seafloor station to Stromboli volcano. This seismicity appears in the form of a continuous seismic signal (tremor-like-signal) as well as a considerable number of shock-like events. We focused on recordings from OBS05 to verify their correlation with Stromboli volcanic activity. From the spectral analysis, we observed low-frequency events (LP events), superposed upon the continuous background noise (tremor). LP events and tremor, showing similar energy fluctuations and frequency content, appear to be produced by the same dynamic processes. We interpret this low-frequency seismicity as probably originating from a continuous uprising of gas bubbles from the deeper part of the Stromboli magmatic column. This could highlight the existence of a deeper source for low-frequency seismicity.
    Description: Published
    Description: L04305
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano-seismology ; low-frequency events ; tremor ; OBSs ; Stromboli (Southern Tyrrhenian Sea) ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 52
    Publication Date: 2017-04-04
    Description: The 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamics of the volcano, marking the passage from a period (March 1993–June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveals a southward motion of the upper southern part of the volcano, driven by a NNW–SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
    Description: This work was funded by the Istituto Nazionale di Geofisica e Vulcanologia and by the Dipartimento per la Protezione Civile (Italy).
    Description: Published
    Description: 78–86
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: stress release ; dike ; volcano-tectonics ; flank instability ; Mt. Etna ; instrumental monitoring ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 53
    Publication Date: 2017-04-04
    Description: Between December 2004 and August 2005, more than 50,000 long-period events (LP) accompanied by very-long period pulses (VLP) were recorded at Mt. Etna, encompassing the effusive eruption which started in September 2004. The observed activity can be explained by the injection of a gas slug formed within the magmatic column into an overlying cavity filled by either magmatic or hydrothermal fluids, thus triggering cavity resonance. Although a large number of LP events exhibit similar waveforms before the eruption, they change significantly during and after the eruption. We study the temporal evolution of the LP-VLP activity in terms of the source movement, change of the waveforms, temporal evolution of the dominant resonance frequencies and the source Q factor and changes in the polarization of the signal. The LP source locations before and after the eruption, respectively, do not move significantly, while a slight movement of the VLP source is found. The intensity of the LP events increases after the eruption as well as their dominant frequency and Q factor, while the polarization of the signals changes from predominantly transversal to pure radial motion. Although in previous studies a link between the observed LP activity and the eruption was not found, these observations suggest that such a link was established at the latter end of the eruptive sequence, most likely as a consequence of a reestablishment of the pressure balance in the plumbing system, after it was undermined due to the discharge of large amounts of resident magma during the eruption. Based on the polarization properties of the signal and geological setting of the area, a fluid-filled crack is proposed as the most likely source geometry. The spectral analysis based on the autoregressive-models (SOMPI) is applied to the signals in order to analyse the resonance frequencies and the source Q-factors. The results suggest water and basalt at low gas volume fraction as the most likely fluids involved in the source process. Using theoretical relations for the “slow waves” radiated from the fluid-filled crack, we also estimate the crack size for both fluids, respectively.
    Description: Published
    Description: 205-220
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: volcano seismology ; long-period seismicity ; Etna volcano ; volcano monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 54
    Publication Date: 2017-04-04
    Description: Data from two dense arrays of short-period seismometers are used to retrieve source locations of the explosion quakes at Stromboli volcano. Slowness vectors stimated at both arrays with the zero-lag cross-correlation technique constitute the experimental data set. A probabilistic approach based on a grid search spanning the volcano interior is used to calculate the probability of the source location. Results depict a shallow source, located beneath the crater area, at depths not greater than 500 m below the surface. Results are slightly different from, but comparable to, those obtained in a companion experiment carried out in the same time period using a broad-band seismometer network, which show a source shifted some hundreds of meters northwest of the crater area. The method is revealed to be effective and useful for future studies having the purpose of real-time tracking of the explosion quakes and tremor.
    Description: Published
    Description: 123-142
    Description: partially_open
    Keywords: Stromboli ; Array ; Explosion quake ; Source location ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 55
    Publication Date: 2017-04-04
    Description: In this paper we discuss the data collected by a large aperture array of broadband seismometers and a continuously recording gravity station during the 2002–2003 eruption of Etna volcano (Italy). Seismic signals recorded during the eruption are dominated by volcanic tremor whose energy spans the 0.5–5 Hz frequency band. On three different occasions (12 November, 19–20 November and 8–9 December 2002), we observed marked increases of the tremor amplitude (up to a factor of 4), which occurred simultaneously with gravity decreases (up to 30 μGal). The three concurrent gravity/tremor anomalies last 6 to 12 hours and terminate with rapid (up to 2 hours) changes, after which the signals return back to their original levels. Based on volcanological observations encompassing the simultaneous anomalies, we infer that the accumulation of a gas cloud at some level in the conduit plexus feeding a new eruptive vent could have acted as a joint source. This study highlights the potential of joint gravity–seismological analyses to both investigate the internal dynamic of a volcano and to improve the confidence of volcanic hazard assessment.
    Description: Published
    Description: 616-629
    Description: reserved
    Keywords: Etna ; volcanic tremor ; gravity changes ; foam layer ; 04. Solid Earth::04.03. Geodesy::04.03.04. Gravity anomalies ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 56
    Publication Date: 2017-04-03
    Description: A lava emission started at Mt. Etna, Italy, on 7 September, 2004. Neither earthquake seismicity heralded or accompanied the opening of the fracture field from which the lava poured out, nor volcanic tremor changed in amplitude and frequency content at the onset of the effusive activity. To highlight long-term changes, we propose a method for the location of the tremor source based on a 3D grid search, using the amplitude decay of the seismic signal, from January to November 2004. We find the centroid of the tremor source within a zone close to and partially overlapped with the summit craters (pre-effusive phase), which extended up to 2 km south of them (effusive phase). The depths are of between 1698 and 2387 m a.s.l. We hypothesize the lava effusion stemmed from a degassed magma body, although we find evidence of temporary magma overpressure conditions, such as those documented on 25 September.
    Description: Published
    Description: L09304
    Description: reserved
    Keywords: NONE ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 57
    Publication Date: 2017-04-04
    Description: On 5 April 2003 at 07:13 GMT (09:13 local time) a violent vulcanian explosion occurred at Stromboli volcano. At the time of the event an eruptive crisis was ongoing at the volcano with a lava flow outpouring along the Sciara del Fuoco flank. The seismic signals related to the event were recorded by 8 permanent broadband stations and gives information about the eruption kinematics. An ultra-longperiod signal (period 〉 20 s), that we interpret as the effect of the ground tilt on the broadband sensors, starts about 4 min before and terminates about 1 min after the explosion. On the basis of the radial pattern of tilt directions we conclude that this signal is the effect of the deformation of the volcanic edifice, due to the rapid rising of a batch of magma, its ejection and the magma column readjustment. About 1 min before the explosion we observe an high frequency signal (period 〈 0.1 s) that we believe to be related to the vesiculation of the rising batch of gas-rich magma. At 07:13:35 GMT a powerful very-long-period signal (period 2 20 s), marking the onset of the explosive fragmentation, is recorded. This is confirmed by a blast wave following few seconds later. The remaining seismic signal (more than 3 min), shows an higher frequency content being related only to the fall of ballistic ejecta and to landslides along Sciara del Fuoco.We propose the implementation of an early warning system for the short-term forecast of such explosions, based on the real-time automatic detection of the tilt signals preceding such events.
    Description: Published
    Description: L08308
    Description: reserved
    Keywords: NONE ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 58
    Publication Date: 2017-04-04
    Description: In the text
    Description: Published
    Description: 1545-1548
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: anisotropy ; eruptive fracture ; Mt. Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 59
    Publication Date: 2017-04-04
    Description: A detailed structural and geophysical study of the Somma–Vesuvius volcanic complex was carried out by integrating mesostructural measurements, focal mechanisms and shear-wave splitting analysis. Fault-slip and focal mechanism analysis indicate that the volcano is affected by NW–SE-, NE–SW-trending oblique-slip faults and by E–W-trending normal faults. Magma chamber s. responsible for plinianrsub-plinian eruptions i.e. A.D. 79 and 1631. formed inside the area bounded by E–W-trending normal faults. The post-1631 fissural eruptions i.e. 1794 and 1861.occurred along the main oblique-slip fault segments. The movements of the Vesuvius faults are mainly related to the regional stress field. A local stress field superposed to the regional one is also present but evidences of magma or gravity induced stresses are lacking. The local stress field acts inside the caldera area being related to fault reactivation processes. The present-day Vesuvius seismic activity is due to both regional and local stress fields. Shear-wave splitting analysis reveals an anisotropic volume due to stress induced cracks NW–SE aligned by faulting processes. Since the depth extent of the anisotropic volume is at least 6 km b.s.l., we deduce the NW–SE-trending oblique-slip fault system represents the main discontinuity on which lies the volcano. This discontinuity is responsible for the morphological lowering of the edifice in its southwestern side.
    Description: Published
    Description: 199-218
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: structure of volcanoes ; stress field ; seismology ; tectonics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 60
    Publication Date: 2017-04-04
    Description: Northern Apulia is an emerged portion of the Adriatic microplate, representing the foreland–foredeep area of a stretch of the Apennine chain in southern Italy. The interaction between the relatively rigid microplate and the contiguous more deformable domains is responsible for the intense seismicity affecting the chain area. However strong, sometimes even disastrous, earthquakes have also hit northern Apulia on several occasions. The identification of the causative faults of such events is still unclear and different hypotheses have been reported in literature. In order to provide guidelines and constraints in the search for these structures, a comprehensive re-examination and reprocessing of all the available seismic data has been carried out taking into consideration 1) the characteristics of historical events, 2) the accurate relocation of events instrumentally recorded in the last 20 years, 3) the determination of focal mechanisms and of the regional stress tensor. The results obtained bring to light a distinction between the foreland and foredeep areas. In the first region there is evidence of a regional stress combining NWcompression and NE extension, thus structures responsible for major earthquakes should be searched for among strike–slip faults, possibly with a slight transpressive character. These structures could be either approximately N–S oriented sinistral or E–Wdextral faults. In the foredeep region there is a transition toward transtensive mechanisms,with strikes similar to those of the previous zone, or maybe also towardsNWoriented normal faults,more similar to those prevailing in the southern Apennine chain in relation to a dominant NE extension; this appears to be the effect of a reduction of the NW compression, probably due to a decrease in efficiency of stress transmission along the more tectonised border of the Adriatic microplate.
    Description: Published
    Description: 9 - 35
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Northern Apulia ; Historical earthquakes ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 61
    Publication Date: 2017-04-04
    Description: Following the significant ground uplift (1.8 m) of the 1982–1984 bradyseismic crisis, the recent history of Campi Flegrei volcanic complex (Italy) has been dominated by a subsidence phase. Recent geodetic data demonstrate that the subsidence has terminated, and that positive ground deformation renewed in November 2004, at a low but accelerating rate leading to about 4 cm of uplift by the end of October 2006. As in previous episodes, ground uplift has been accompanied by swarms of micro-earthquakes (M ≤ 1.4) in three distinct episodes: October 2005, October 2006 and December 2006. Hypocenters of these earthquakes are mainly located beneath the Solfatara Volcano at depths ranging between 0.5 and 4 km. Inversion of S-wave spectra indicates source radius and stress drop on the order of 30–60 m and 104–9 × 105 Pa, respectively. Fault plane solutions indicate predominantly normal mechanisms. Accompanying the October 2006 swarm, we detected intense long-period (LP) activity for about 1 week. These signals consist of weak, monochromatic oscillations whose spectra exhibit a main peak at frequency 0.8 Hz. This peak is common to all the stations of the network, and not present in the noise spectra, suggesting that it is a source effect. About 75% of the detected LPs cluster into three groups of mutually similar events. Adjustment of waveforms using cross-correlation allows for precise alignment and stacking, which enhances signal onsets and permits accurate absolute arrival picks, and thus better absolute as well as relative locations. Locations associated with the three different clusters are very similar, and appear to delineate the SE rim of the Solfatara Volcano at a depth of about 500 m. The most likely source process for the LP events involves the resonance of a fluid-filled, buried cavity. Quality factors of the resonator cluster in a narrow interval around 4, which is consistent with the vibration of a buried cavity filled with a water-vapour mixture at poor gas-volume fractions. We propose a conceptual model to interpret the temporal and spatial patterns of the observed seismicity.
    Description: Published
    Description: 14-24
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Long-period seismicity ; Volcano monitoring ; Caldera ; Hydrothermal system ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 62
    Publication Date: 2017-04-04
    Description: Tomographical results are commonly presented in the form of color images and not much statistical quantification has been carried out on the derived models. Correlation between different depths can shed important light concerning the dynamics. We have generalized the application of multidimensional wavelets to investigate the products of two field variables, such as the cross-spectrum, which is of paramount importance for quantifying the correlation between two depth levels of seismic tomography with a multiple-scale character. For two multidimensional fields A and B, we calculate the correlation C by projecting this as an Hermitian inner product in physical space with a two-dimensional (2D), fourth derivative of the Gaussian wavelet as the weighting function. The correlation function C becomes now a multi-scaled function, a map cast in terms of both the scale and location of the wavelet transform. Having calculated C, we can delineate the locations and length-scales of the prominent features in the landscape of the correlation function. This wavelet formulation is very general and can be extended to other types of statistical analysis, for example in a Kalman filter system. We have used a high-resolution (finer than 1◦) seismic tomographical model for analyzing the extent of mantle layering under Europe by focussing on the different length-scales in the correlation function involving the 3D seismic anomalies lying between 400 and 600 km depth. Between the depths of 500 and 600 km under Europe, the wavelet correlation analysis shows that an ellipse-shaped object exists with an area of 2000 km × 4000 km having a strong correlation for length-scales of around 400 km, and weaker correlation for shorter length scales of around 150 km. On the other hand, between depths of 400 and 600 km, the correlation deteriorates on the long length scales and becomes even worse at the short length scales. From the wavelet correlation spectra, we can extract an horizontal characteristic length scale of around 100 km, which may be related to the boundary interaction between the slab and the ambient mantle. The correlation results suggest that the thickness of the recumbent fast (cold) material in the transition zone is between 100 and 150 km. This large elliptical pattern of presumably cold material would act to inhibit the vigor of mantle convection locally beneath Europe today.
    Description: Published
    Description: 125–139
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: wavelets ; correlation ; tomography ; transition zone ; Mediterranean ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 63
    Publication Date: 2017-04-04
    Description: Subduction zones appear primarily controlled by the polarity of their direction, i.e., W-directed or E- to NNE-directed, probably due to the westward drift of the lithosphere relative to the asthenosphere. The decollement planes behave differently in the two end-members. In the W-directed subduction zone, the decollement of the plate to the east is warped and subducted, whereas in the E- to NNE-directed, it is ramping upward at the surface. There are W-directed subduction zones that work also in absence of active convergence like the Carpathians or the Apennines. W-directed subduction zones have shorter life 30–40 Ma.than E- or NE-directed subduction zones even longer than 100 Ma.. The different decollements in the two end-members of subduction should control different PTt paths and, therefore, generate variable metamorphic assemblages in the associated accretionary wedges and orogens. These asymmetries also determine different topographic and structural evolutions that are marked by low topography and a fast ‘eastward’ migrating structural wave along W-directed subduction zones, whereas the topography and the structure are rapidly growing upward and expanding laterally along the opposite subduction zones. The magmatic pair calc-alkaline and alkaline–tholeiitic volcanic products of the island arc and the back-arc basin characterise the W-directed subduction zones. Magmatic rocks associated with E- or NE-directed subduction zones have higher abundances of incompatible elements, and mainly consist of calc-alkaline– shoshonitic suites, with large volumes of batholithic intrusions and porphyry copper ore deposits. The subduction zones surrounding the Adriatic plate in the central Mediterranean confirm the differences among subduction zones as primarily controlled by the geographic polarity of the main direction of the slab. The western margin of the Adriatic plate contemporaneously overridden and underthrust Europe toward the ‘west’ to generate, respectively, the Alps and the Apennines, while the eastern margin subducted under the Dinarides–Hellenides. These belts confirm the characters of the end-members of subduction zones as a function of their geographic polarity similarly to the Pacific subduction zones.
    Description: Published
    Description: 167–208
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: tectonics ; subduction zones ; orogens ; Mediterranean geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 64
    Publication Date: 2017-04-04
    Description: We report on a high-resolution Vp, Vp/Vs and Qp model of the southern Tyrrhenian subduction zone, obtained by the inversion of P- and S wave arrival times and t* values from intraslab seismicity. The arcuate shape of the southern Apennines–Calabrian arc-Sicilian Maghrebides is perfectly mirrored by two rather continuous low and high Vp bands lying beneath the belt system at ca. 25 and 100 km, respectively. Between 100 and 300 km, two independent high Vp slabs lie beneath the Neapolitan region and the southern Tyrrhenian Sea, separated by unperturbed mantle. We suggest that the ca. 150 km-wide slab window beneath the southern Apennines opened after a tear occurring within a composite subduction system, formed by the Apulian continental lithosphere and the Ionian oceanic slab. The abrupt slab rupture induced ultrafast southeastward retreat of the Ionian slab, and the 19 cm/yr spreading of the back-arc oceanic Marsili basin between ca. 2.1 and 1.6 Ma ago. The 25 km low Vp zone beneath the arc denotes continental upper crustal rocks below the chain. Its striking continuity requires a unique orogenic wedge at 25 km depth below the southern Apennines, the Calabrian arc, and the Sicilian Maghrebides. The alternative explanation would imply the ubiquitous occurrence of autochthonous lower plate rocks at 25 km depth, i.e. a puzzling autochthonous continental Calabria. The Ionian slab beneath Calabria shows high Vp, high Qp and low Vp/Vs anomalies, typical of old oceanic lithosphere. Intermediate depth seismicity is concentrated within its thin oceanic crust, suggesting the occurrence of vigorous metamorphism. The slab dehydration promotes the melting of the overlying mantle, as testified by high Vp/Vs and low Qp anomalies between the slab and the Aeolian magmatic arc.
    Description: Published
    Description: 408-423
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: seismic tomography ; recent evolution of the Ionian slab ; deep earthquakes slab dehydration and magmatism ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 65
    Publication Date: 2017-04-04
    Description: In curved orogenic systems where thrusting and vertical-axis rotations have been documented, it is possible to determine whether the curvature is secondary or progressive based on the timing between the two motions. The South-Central Unit of the Southern Pyrenees provides an opportunity to investigate relationships between thrusting, folding, and vertical-axis rotation because of unusual preservation of Tertiary synorogenic sedimentary strata. Paleomagnetic samples were collected from 51 sites in the upper Eocene-lower Oligocene continental synorogenic strata of the Oliana anticline, a foreland fold along the eastern margin of the South-Central Unit. Site-mean characteristic remanent magnetization directions were determined from 17 sites through thermal demagnetization and principal component analysis. In addition, 72 samples were collected from 39 stratigraphic levels spanning the Upper Eocene marine marls and treated with thermal and alternating field demagnetization techniques. Of these, 53 samples yielded demagnetization trajectories that further constrained the rotation. Comparison of the observed mean paleomagnetic direction from the Oliana anticline with the expected direction indicates a counterclockwise rotation (R ± ΔR) of 20.3° ± 10.9°. Based on the stratigraphic horizons recording the rotation, the age of the rotation is younger than ~34 Ma (after deposition of Unit 3). Data covering the Upper Eocene-Lower Oligocene time interval indicate a similar magnitude of rotation, suggesting that late stage emplacement of thrust sheets hinterlandward of the Oliana anticline controlled the rotation, with rotation accommodated along regionally extensive evaporites. The well-constrained timing relationships between thrusting and rotation and the regional and local transport directions, suggest that the South-Central Unit is a progressive curve that formed through distributed shortening.
    Description: Published
    Description: 435-449
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Pyrenees ; Oliana anticline ; synorogenic strata ; paleomagnetism ; salients ; 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::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 66
    Publication Date: 2017-04-04
    Description: The magnetic field observed at the Earth’s surface is not a stationary feature. It is characterized by time variations ranging from milliseconds (micropulsations) to millions of years (the time interval between field reversals). Time variations with periods of a year or longer are related to Earth’s outer core sources, whereas for shorter timescales an external origin is invoked (i.e., solar activity). One of the most interesting time variations of the geomagnetic field is represented by the “geomagnetic jerk.” It is idealized as a rapid change in the slope of the secular variation, defined as the first derivative of the geomagnetic field. This means that the secular variation roughly appears as a series of straightline segments separated by geomagnetic jerks.
    Description: Published
    Description: 123
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: 3.4. Geomagnetismo
    Description: N/A or not JCR
    Description: reserved
    Keywords: Sumatra Earthquake ; Geomagnetic Jerk ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 67
    Publication Date: 2017-04-04
    Description: The tectonic escarpments locally known as ‘Timpe’ cut a large sector of the eastern flank of Etna, and allow an ancient volcanic succession dating back to 225 ka to be exposed. Geological and volcanological investigations carried out on this succession have allowed us to recognize relevant angular unconformities and volcanic features which are the remnants of eruptive fissures, as well as important changes in the nature, composition and magmatic affinity of the exposed volcanics. In particular, the recognition in the lower part of the succession of important and unequivocal evidence of ancient eruptive fissures led us to propose a local origin for these volcanics and to revise previous interpretations which attributed their westward-dipping to the progressive tectonic tilting of strata. These elements led us to reinterpret the main features of the volcanic activity occurring since 250 ka BP and their relationship with tectonic structures active in the eastern flank of Etna. We propose a complex paleo-environmental and volcanotectonic evolution of the southeastern flank of Mt. Etna, in which the Timpe fault system played the role of the crustal structure that allowed the rise and eruption of magmas in the above considered time span.
    Description: Published
    Description: 289-306
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Mount Etna ; tectonics ; fisssure eruptions ; columnar basalt ; fault escarpment ; xenoliths ; 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::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 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::04.07.04. Plate boundaries, motion, and tectonics ; 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::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 68
    Publication Date: 2017-04-04
    Description: We present a detailed analysis of the source properties of Long-Period (LP) signals recorded at Campi Flegrei Caldera (Italy) during the last (2005–2006) mini-uplift episode. Moment Tensor inversion via full-waveform modelling of broad-band seismograms indicates a crack-like source with a significant volumetric component. From auto-regressive modelling of the signal's tail we evaluate the dominant frequency and the attenuation factor of the oscillating source. Considering the acoustic properties of a fluid-filled crack, these values are consistent with the resonant oscillations of a crack filled by a water–gas mixture at variable gas–volume fraction. For these fluids, the crack size would be on the order of 40–420 m, a size range which is consistent with the spatial spreading of LP hypocenters. Analysis of temporally-correlated time series of seismological and geochemical data indicates that climaxing of LP activity was preceded by swarms of volcano-tectonic (VT) events and rapidly followed by a consistent increase of both thermal emissions and gas fluxes recorded at the surface (1 month — 2/3 days, respectively). Following these observations, we propose a conceptual model where VT activity increases permeability of the medium, thus favouring fluid mobility. As a consequence, the hydrothermal system experiences pressure perturbations able to trigger its resonant, LP oscillations.
    Description: Published
    Description: 1035–1044
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Campi Flegrei caldera ; Long-Period earthquakes ; crack model ; Sompi method ; gas composition ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 69
    Publication Date: 2017-04-04
    Description: In the present paper we describe the results of a seismic field survey carried out at Copahue Volcano, Southern Andes, Argentina, using a small-aperture, dense seismic antenna. Copahue Volcano is an active volcano that exhibited a few phreatic eruptions in the last 20 years. The aim of this experiment was to record and classify the background seismic activity of this volcanic area, and locate the sources of local earthquakes and volcanic tremor. Data consist of several volcano-tectonic (VT) earthquakes, and many samples of back-ground seismic noise. We use both ordinary spectral, and multi-spectral techniques to measure the spectral content, and an array technique [Zero Lag Cross Correlation technique] to measure the back-azimuth and apparent slowness of the signals propagating across the array.We locate VT earthquakes using a procedure based on the estimate of slowness vector components and S–P time. VT events are located mainly along the border of the Caviahue caldera lake, positioned at the South-East of Copahue volcano, in a depth interval of 1–3 kmbelow the surface. The background noise shows the presence of many transients with high correlation among the array stations in the frequency band centered at 2.5 Hz. These transients are superimposed to an uncorrelated background seismic signal. Array solutions for these transients show a predominant slowness vector pointing to the exploited geothermal field of “Las Maquinitas” and “Copahue Village”, located about 6 km north of the array site. We interpret this coherent signal as a tremor generated by the activity of the geothermal field.
    Description: Published
    Description: 284–294
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic seismicity ; volcanic tremor ; seismic array ; volcano tectonic earthquakes ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 70
    Publication Date: 2017-04-04
    Description: We determine the three-dimensional distribution of P- and S-wave velocities for Central São Miguel Island (Azores, Portugal) by tomographic inversion of local earthquake arrival times. We use P- and S-phases from 289 earthquakes recorded by a network of 20 seismometers. The model shows good resolution in the shallowest 5–6 km, as illustrated by different resolution tests. There are several velocity anomalies, interpreted as pyroclastic deposits, intrusive bodies, geothermal fields, and the effects of tectonics. A low Vp zone marks Furnas caldera, probably evidencing volcaniclastic sediments with development of intense geothermal activity. Another low Vp zone extends in correspondence of the highly fractured area between Fogo and the north coast. Conversely, strong positive anomalies are found south of Fogo and northwest of Furnas. They are interpreted in terms of high-density deposits and remnants of a plutonic intrusion. These interpretations are supported by the distribution of Vp/Vs, and are consistent with previous geological, geochemical, and geophysical data.
    Description: Published
    Description: 8-18
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Seismic tomography ; Volcano seismology ; Crustal structure ; Azores ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 71
    Publication Date: 2017-04-04
    Description: The origin of forces driving the deformation of the continental crust near subduction zones and especially in backarc regions is debated. Thiswork is based on a compilation of SKS fast splitting directions that give an image of flowlines in themantle around theMediterranean subduction zones and a comparisonwith stretching and shear directions in metamorphic core complexes that show the pattern of deformation at the scale of the middle and lower crusts.We find that : (1) the two sets of directions are parallel in the three main backarc regions, namely the Alboran Sea, the Tyrrhenian Sea and the Aegean Sea showing that the lithosphere deformswith the samedirection of stretching in the crust and themantle, suggesting that (2) crustal deformation ismainly driven frombelowby slab retreat, and (3) the lithospheric fabric is reset within a few millions of years in backarc environments.
    Description: Published
    Description: 198–209
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: subduction ; seismic anisotropy ; backarc extension ; slab retreat ; stretching lineation ; metamorphic core complexes ; Mediterranean ; Aegean ; Tyrrhenian ; Alboran ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 72
    Publication Date: 2017-04-04
    Description: Nitrogen isotopes , N2/36Ar and 3He/4He were measured in volcanic fluids within different geodynamic settings. Subduction zones are represented by Aeolian archipelago, Mexican volcanic belt and Hellenic arc, spreading zones – by Socorro island in Mexico and Iceland and hot spots by Iceland and Islands of Cabo Verde. The δ15N values, corrected for air contamination of volcanic fluids, discharged from Vulcano Island (Italy), highlighted the presence of heavy nitrogen (around +4.3 ±0.5‰). Similar 15N values (around +5‰), have been measured for the fluids collected in the Jalisco Block, that is a geologically and tectonically complex forearc zone of the northwestern Mexico [1]. Positive values (15N around +3‰) have been also measured in the volcanic fluids discharged from Nysiros island located in the Ellenic Arc characterized by subduction processes. All uncorrected data for the Socorro island are in the range of -1 to -2‰. The results of raw nitrogen isotope data of Iceland samples reveal more negative isotope composition (about -4.4‰). On the basis of the non-atmospheric N2 fraction (around 50%) the corrected data of 15N for Iceland are around -16‰, very close to the values proposed by [2]. In a volcanic gas sample from Fogo volcano (Cabo Verde islands) we found a very negative value: -9.9‰ and -15‰ for raw and corrected values, respectively.
    Description: Geochimica et Cosmochimica Acta
    Description: Published
    Description: Davos, Switzerland
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: open
    Keywords: Nitrogen Isotopes ; Helium Isotopes ; Volcanic fluids ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 73
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    Unknown
    AGU
    In:  Citation: Tedesco, D., et al. (2007), Cooperation on Congo Volcanic and Environmental Risks, Eos Trans. AGU, 88(16), 177.
    Publication Date: 2024-05-09
    Description: Article
    Description: On 17 January 2002, the Nyiragongo volcano (1.52°S, 29.25°E, 3469 meters above sea level), located about 18 kilometers north of Lake Kivu in the Democratic Republic of Congo, erupted, releasing a volume of 14-34 million cubic meters of lava. Lava flows originated from north-south oriented fractures that rapidly developed along the southern flank of the volcano. Two lava flows divided the nearby city of Goma (~500,000 people) into two parts, forcing a rapid exodus of the population into Rwanda. One of these lava flows ran into Lake Kivu, encroaching 60 meters below lake level with a submerged lava volume of 1 million cubic meters. About 15% of the town was directly affected, leaving approximately 120,000 people homeless. At least 170 people died as a direct consequence of the eruption
    Description: American Geophysical Union
    Description: Published
    Description: 177-188
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: N/A or not JCR
    Description: reserved
    Keywords: Volcanology ; Telemetered Seismic Network ; Effusive volcanism ; Volcanology ; Experimental volcanism ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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