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Sarti, F.
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- PublicationRestrictedThe source motion of 2003 Bam (Iran) earthquake constrained by satellite and ground-based geodetic data(2007-06)
; ; ; ; ; ; ; ;Peyret, M.; G´eosciences Montpellier, UMR 5573, Universit´e de Montpellier II, France. ;Chéry, J.; G´eosciences Montpellier, UMR 5573, Universit´e de Montpellier II, France. ;Djamour, Y.; National Cartographic Center, Tehran, Iran ;Avallone, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Sarti, F.; European Space Agency, Frascati, Italy ;Briole, P.; Institut de Physique du Globe, Paris, France ;Sarpoulaki, M.; National Cartographic Center, Tehran, Iran; ; ; ; ; ; The interpretation of coseismic surface deformation measurements through inversion techniques is of major importance to understand the mechanical behaviour of a seismic fault. Dense geodetic data sets in the vicinity of the ruptured fault provide unique constraints on detailed fault geometry and slip distribution at depth, making them complementary to seismological data. Bam earthquake (Mw 6.6, 2003 December 26) induced surface deformation has been precisely mapped by Envisat ASAR interferometry and by subpixel correlation techniques applied to Spot-5 and ASAR amplitude images. These oblique and horizontal estimations of deformation have been completed with one levelling profile along the main road crossing the rupture from west to east. We process these data (separately and jointly) in a two-step inversion technique, within the elastic half-space theory framework. Our objective is to determine the dislocation model at depth that satisfies simultaneously all the geodetic constraints. Also, we estimate the relative contribution of each geodetic data set to this inversion process. We first use a stochastic direct approach called neighbourhood algorithm in order to estimate the average characteristics of the rupture, and their relative uncertainty. Constraining in this way the geometry of the ruptured fault, we then linearize the inverse problem and compute the slip distribution on the fault using a standard weighted least-square technique, assuming the solution is smooth to some degree. At each step, we discuss the optimal models, their stability as well as the relative influence of each data set on the derived models parameters. Our preferred model reveals a shallow dislocation on a quasi-vertical fault, slightly dipping towards east. The slip vector has a strike-slip component as high as 2 m, while the dip-slip component seems negligible. However, the estimation of the resolution matrices emphasizes the fact that the details of deep fault slip distribution remain out of the scope of this ill-conditioned inverse problem. Yet, our preferred model suggests a main dislocation limited at depth between 1 and 6 km. By contrast, the aftershocks observed in the months following the earthquake are located just beneath the estimated main shock.176 29 - PublicationOpen AccessThe Sentinel-1 mission for the improvement of the scientific understanding and the operational monitoring of the seismic cycle(2012)
; ; ; ; ; ; ;Salvi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Stramondo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Funning, G. J.; University of California ;Ferretti, A.; TeleRilevamento Europa ;Sarti, F.; European Space Agency – ESA/ESRIN ;Mouratidis, A.; European Space Agency – ESA/ESRIN; ; ; ;; We describe the state of the art of scientific research on the earthquake cycle based on the analysis of Synthetic Aperture Radar (SAR) data acquired from satellite platforms. We examine the achievements and the main limitations of present SAR systems for the measurement and analysis of crustal deformation, and envision the foreseeable advances that the Sentinel-1 data will generate in the fields of geophysics and tectonics. We also review the technological and scientific issues which have limited so far the operational use of satellite data in seismic hazard assessment and crisis management, and show the improvements expected from Sentinel-1 data226 500