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Departamento de Volcanología, Museo Nacional de Ciencias Naturales, CSIC, Madrid Spain
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- PublicationRestrictedEvidence of a partial melt zone beneath Stromboli volcano (Italy) from inversion of teleseismic receiver functions(2009-07-01)
; ; ; ;Martinez-Arévalo, C.; Museo Nacional de Ciencias Naturales. CSIC, Madrid ;Musumeci, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Patanè, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; Teleseismic body waves from broadband seismic stations are used to investigate the crustal and uppermost mantle structure of Stromboli volcano through inversion of the receiver functions (RFs). First, we computed RFs in the frequency domain using a multiple-taper spectral correlation technique. Then, the nonlinear neighbourhood algorithm was applied to estimate the seismic shear wave velocity of the crust and uppermost mantle and to define the main seismic velocity discontinuities. The stability of the inversion solution was tested using a range of initial random seeds and model parameterizations. A shallow Moho, present at depth of 14.8 km, is evidence of a thinned crust beneath Stromboli volcano. However, the most intriguing and innovative result is a low S velocity layer in the uppermost mantle, below 32 km. The low S velocity layer suggests a possible partial melt region associated with the volcanism, as also recently supported by tomographic studies and petrological estimations.465 32 - PublicationOpen AccessReceiver Function Analysis at Stromboli Volcano (Italy)(2007-04-15)
; ; ; ; ; ;Martinez-Arévalo, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Musumeci, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Barberi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;De Gori, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Patanè, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; ; ; This study focuses on constraining the crust and upper mantle discontinuities at Stromboli volcano by applying the receiver function (RF) analysis. This technique utilizes the waveforms of P-SV conversions generated by discontinuities to infer the structure beneath the seismic stations. RFs have been obtained by deconvolving the vertical component of teleseismic P-wave records from the corresponding rotate horizontal components applying the Multi-Taper Spectral Correlation technique. For this study the seismograms of about 125 teleseismic earthquakes (M greater than 6.0), recorded between 2004 and 2006 at 13 broad-band seismic stations deployed by the INGV, have been considered. A preliminar characterization of the structure beneath the stations has been inferred from the stacking of teleseismic Ps converted waves and multiply converted waves at the seismic interface. The analysis, at frequency of 1 and 2 Hz, show a horizontal seismic discontinuity at an average depth of about 17 km and a Vp/Vs ratio lower than 1.73. This discontinuity explains the positive pulses about 1.9 s and 7.5 s after the direct P arrival. These pulses can be interpreted as Ps and PpPs converted phases, respectively. The depth of this discontinuity is in agreement with the Moho-depth obtained in independent studies.162 98 - PublicationRestrictedFault plane orientations of microearthquakes at Mt. Etna from theinversion of P-wave rise times(2010)
; ; ; ; ; ;de lorenzo, S.; Dipartimento di Geologia e Geofisica & Centro Interdipartimentale per il Rischio Sismico e Vulcanico, Università di Bari, Italy ;Giampiccolo, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Martinez-Arevalo, C.; Departamento de Volcanología, Museo Nacional de Ciencias Naturales, CSIC, Madrid Spain ;Patanè, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Romeo, A.; Dipartimento di Geologia e Geofisica & Centro Interdipartimentale per il Rischio Sismico e Vulcanico, Università di Bari, Italy; ; ; ; A crucial point in the analysis of tectonic earthquakes occurring in a volcanic area is the inference of the orientation of the structures along which the ruptures occur. These structures represent zones of weakness which could favor the migration of melt toward the surface and the assessment of their geometry is a fundamental step toward efficient evaluation of volcanic risk. We analyzed a high-quality dataset of 171 lowmagnitude, tectonic earthquakes that occurred at Mt. Etna during the 2002–2003 eruption. We applied a recently developed technique aimed at inferring the source parameters (source size, dip and strike fault) and the intrinsic quality factor Qp of P waves from the inversion of rise times. The technique is based on numerically calibrated relationships among the rise time of first P waves and the source parameters for a circular crack rupturing at a constant velocity. For the most of the events the directivity source effect did not allow us to constrain the fault plane orientation. For a subset of 45 events with well constrained focal mechanisms we were able to constrain the “true” fault plane orientation. The level of resolution of the fault planes was assessed through a non linear analysis based on the random deviates technique. The significance of the retrieved fault plane solutions and the fit of the assumed source model to data were assessed through a χ-square test. Most of the retrieved fault plane solutions agree with the geometrical trend of known surface faults. The inferred source parameters and Qp are in agreement with the results of previous studies285 23