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Dipartimento di Ingegneria Civile ed Ambientale, Universit`a degli Studi di Perugia, Perugia, Italy
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- PublicationRestrictedCoseismic and initial postseismic slip of the 2009 Mw 6.3 l’Aquila earthquake, Italy, from GPS measurements(2010-06)
; ; ; ; ; ; ; ; ; ; ; ; ;Cheloni, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;D'Agostino, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;D'Anastasio, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Avallone, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Mantenuto, S.; Leica Geosystems S.p.A., Italy, Roma ;Giuliani, R.; Dipartimento Protezione Civile, Roma, Italy ;Mattone, M.; Dipartimento Protezione Civile, Roma, Italy ;Calcaterra, S.; Istituto Superiore per la Protezione e la Ricerca Ambientale, Roma, Italy ;Gambino, P.; Istituto Superiore per la Protezione e la Ricerca Ambientale, Roma, Italy ;Dominici, D.; Dipartimento di Architettura e Urbanistica, Universit`a degli Studi dell’Aquila, L’Aquila, Italy ;Radicioni, F.; Dipartimento di Ingegneria Civile ed Ambientale, Universit`a degli Studi di Perugia, Perugia, Italy ;Fastellini, G.; Dipartimento di Ingegneria Civile ed Ambientale, Universit`a degli Studi di Perugia, Perugia, Italy; ; ; ; ; ; ; ; ; ; ; Here we report the preliminary results of GPS data inversions for coseismic and initial afterslip distributions of the Mw 6.3 2009 April 6 L’Aquila earthquake. Coseismic displacements of continuous and survey-style GPS sites, show that the earthquake ruptured a planar SW-dipping normal fault with ∼0.6 m average slip and an estimated moment of 3.9 × 1018 Nm. Geodetic data agree with the seismological and geological information pointing out the Paganica fault, as the causative structure of the main shock. The position of the hypocentre relative to the coseismic slip distribution supports the seismological evidence of southeastward rupture directivity. These results also point out that the main coseismic asperity probably ended downdip of the Paganica village at a depth of few kilometres in agreement with the small (1–10 cm) observed surface breaks. Time-dependent post-seismic displacements have been modelled with an exponential function. The average value of the estimated characteristic times for near-field sites in the hanging-wall of the fault is 23.9 ± 5.4 d. The comparison between coseismic slip and post-seismic displacements for the first 60 d after the main shock, shows that afterslip occurred at the edges of the main coseismic asperity with a maximum estimated slip of ∼25 cm and an equivalent seismic moment of 6.5 × 1017 Nm. The activation of the Paganica fault, spatially intermediate between the previously recognized main active fault systems, suggests that strain accumulation in the central Apennines may be simultaneously active on distinct parallel fault systems.432 59 - PublicationRestrictedContemporary crustal extension in the Umbria–Marche Apennines from regional CGPS networks and comparison between geodetic and seismic deformation(2009)
; ; ; ; ; ; ; ; ; ;D'Agostino, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Mantenuto, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;D'Anastasio, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Avallone, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Barchi, M.; Dipartimento Scienze Geologiche, Università di Perugia ;Collettini, C.; Dipartimento Scienze Geologiche, Università di Perugia ;Radicioni, F.; Dipartimento Ingegnerai Civile Ambientale, Università di Perugia ;Stoppini, A.; Dipartimento Ingegnerai Civile Ambientale, Università di Perugia ;Fastellini, G.; Dipartimento Ingegnerai Civile Ambientale, Università di Perugia; ; ; ; ; ; ; ; Here we report the results of the analysis of a GPS velocity field in the Umbria–Marche Apennines (central Italy) obtained from the integration of diverse geodetic networks. The velocity field obtained shows a high degree of consistency both spatially and in terms of comparison with independent information, despite the limited time span of some GPS stations. Starting from the velocity field we derive a continuous strain rate field applying a spline interpolation technique which provide a smooth estimate of the deformation field. The main feature of the resulting strain rate field is a continuous high (N50 nanostrain/year) strain rate belt coincident with the area of largest historical and instrumental seismic release. The model directions of the principal axes agree with geological and seismological information indicating NE–SW extension. We transform the strain rate field into geodetic moment rate using the Kostrov formula to evaluate the potential seismic activity of the region and compare it with actual seismic release in the last 720 years from MwN5.5 earthquakes. This comparison highlights a large possible deficit in the seismic release with respect to the overall potential seismic activity, particularly concentrated in the northern part of the study area. This discrepancy can be resolved with either a large amount of seismicity to be released in the near future or significant aseismic slip and deformation.343 40