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New insights on seismicity pattern in the Lucanian Apennines (Southern Italy) and minimum 1D velocity model
Author(s)
Type
Poster session
Language
English
Status
Published
Conference Name
Issued date
April 15, 2007
Conference Location
Vienna
Abstract
We analyzed the seismicity of Southern Italy in the area including Lucanian Apennines and Bradano foredeep, making use of the most recent seismological data base available so far. We re-picked P- and S-wave arrival times recorded by the Italian National Seismic Network (RSNC), operated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV), the SAPTEX temporary array (2001-2004), and the local Eni-Agip seismic network located in the upper Agri Valley. We examined the seismicity of this area in the period between 2001 and 2006, considering events that have magnitudes
greater than 2.0. Firstly, we computed the VP /VS ratio using a modified Wadati method, obtaining a value of 1.83. Secondly, through the use of the Velest code, we carried out an analysis for the one-dimensional (1D) velocity model that approximates the seismic structure of the study area. We relocated the earthquakes and for well recorded events we also computed the focal mechanisms. The denser station coverage allows us to obtain improved hypocenters with respect to those obtained by using only RSNC data. The distribution of events shows two main different domains: the westernmost
characterizing the chain, mostly with shallow earthquakes, and the easternmost
below the Bradano foredeep, with deeper seismicity. Fault-plane solutions were used
for stress inversion. The results of this analysis are consistent with the hypothesis that the Lucanian Apennines is generally characterized by NE-SW extension.
greater than 2.0. Firstly, we computed the VP /VS ratio using a modified Wadati method, obtaining a value of 1.83. Secondly, through the use of the Velest code, we carried out an analysis for the one-dimensional (1D) velocity model that approximates the seismic structure of the study area. We relocated the earthquakes and for well recorded events we also computed the focal mechanisms. The denser station coverage allows us to obtain improved hypocenters with respect to those obtained by using only RSNC data. The distribution of events shows two main different domains: the westernmost
characterizing the chain, mostly with shallow earthquakes, and the easternmost
below the Bradano foredeep, with deeper seismicity. Fault-plane solutions were used
for stress inversion. The results of this analysis are consistent with the hypothesis that the Lucanian Apennines is generally characterized by NE-SW extension.
References
Cassinis, R., S. Scarascia and A. Lozej (2003): The deep crustal structure of Italy and surrounding areas from seismic refraction data. A new synthesis, Boll. Soc. Geol. It.,122, 365-376.
Castello, B., G. Selvaggi, C. Chiarabba and A. Amato (2005): CSI Catalogo della sismicità italiana 1981-2002, versione 1.0 (INGV-CNT, Roma), (on line: http://www.ingv.it/CSI/).
Chatelain, J. L. (1978), Etude fine de la sismicité en zone de collision continentale à l’aide d’un réseau de statios portables: la region Hindu-Kush-Pamir , Thèse de 3 éme cycle, Univ. Paul Sabatier, Toulouse.
Chiarabba, C. and A. Frepoli (1997): Minimum 1D velocity models in Central and Southern Italy: a contribution to better constrain hypocentral determinations, Ann. Geofis., XL (4), 937-954.
Chiarabba, C.,L. Jovane and R. Di Stefano (2005): A new view of Italian seismicity using 20 years of instrumental recordings, Tectonophysics, 395, 251-268.
Cimini , G. B., P. De Gori and A. Frepoli (2006): Passive seismology in Southern Italy: the SAPTEX array, Ann. Geofis., 49 (2/3), 825-840.
CPT Working Group (1999): Catalogo Parametrico dei Forti terremoti Italiani (GNDT-ING-SGA-SSN). (Ed. Compositori, Bologna), pp.88.
Frepoli, A., F. R. Cinti, L. Amicucci, G. B. Cimini, P. De Gori and S. Pierdominici (2005): Pattern of seismicity in the Lucanian Apennines and foredeep (Southern Italy) from recording by SAPTEX temporary array, Ann. Geofis., 48 (6), 1035-1054.
Kissling, E., W. L. Ellsworth, D. Eberhart-Phillips and U. Kradolfer (1994): Initial reference models in local earthquake tomography, J. Geophys. Res., 99, 19635-19646.
Lahr, J. C. (1989): HYPOELLIPSE/Version 2.0: a computer program for determining local earthquake hypocentral parameters, magnitude, and first motion pattern, U. S. Geol. Surv. Open File Rep., 95, 89-116.
Pointoise, B., T. Monfret: Shallow seismogenic zone detected from an offshore-onshore temporary seismic network in the Esmeraldas area (northern Ecuador), Geochem. Geophys. Geosyst., 5 (2), 1-22.
Reasenberg, P. and Oppenheimer (1985): FPFIT, FPPLOT and FPPAGE: FORTRAN computer programs for calculating and displaying earthquake fault-plane solutions, U.S. Geol. Surv. Open-File Rep. 85-739.
Castello, B., G. Selvaggi, C. Chiarabba and A. Amato (2005): CSI Catalogo della sismicità italiana 1981-2002, versione 1.0 (INGV-CNT, Roma), (on line: http://www.ingv.it/CSI/).
Chatelain, J. L. (1978), Etude fine de la sismicité en zone de collision continentale à l’aide d’un réseau de statios portables: la region Hindu-Kush-Pamir , Thèse de 3 éme cycle, Univ. Paul Sabatier, Toulouse.
Chiarabba, C. and A. Frepoli (1997): Minimum 1D velocity models in Central and Southern Italy: a contribution to better constrain hypocentral determinations, Ann. Geofis., XL (4), 937-954.
Chiarabba, C.,L. Jovane and R. Di Stefano (2005): A new view of Italian seismicity using 20 years of instrumental recordings, Tectonophysics, 395, 251-268.
Cimini , G. B., P. De Gori and A. Frepoli (2006): Passive seismology in Southern Italy: the SAPTEX array, Ann. Geofis., 49 (2/3), 825-840.
CPT Working Group (1999): Catalogo Parametrico dei Forti terremoti Italiani (GNDT-ING-SGA-SSN). (Ed. Compositori, Bologna), pp.88.
Frepoli, A., F. R. Cinti, L. Amicucci, G. B. Cimini, P. De Gori and S. Pierdominici (2005): Pattern of seismicity in the Lucanian Apennines and foredeep (Southern Italy) from recording by SAPTEX temporary array, Ann. Geofis., 48 (6), 1035-1054.
Kissling, E., W. L. Ellsworth, D. Eberhart-Phillips and U. Kradolfer (1994): Initial reference models in local earthquake tomography, J. Geophys. Res., 99, 19635-19646.
Lahr, J. C. (1989): HYPOELLIPSE/Version 2.0: a computer program for determining local earthquake hypocentral parameters, magnitude, and first motion pattern, U. S. Geol. Surv. Open File Rep., 95, 89-116.
Pointoise, B., T. Monfret: Shallow seismogenic zone detected from an offshore-onshore temporary seismic network in the Esmeraldas area (northern Ecuador), Geochem. Geophys. Geosyst., 5 (2), 1-22.
Reasenberg, P. and Oppenheimer (1985): FPFIT, FPPLOT and FPPAGE: FORTRAN computer programs for calculating and displaying earthquake fault-plane solutions, U.S. Geol. Surv. Open-File Rep. 85-739.
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