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Can Geodynamics benefit from Satellite gravity? The case study of Andaman-Sumatra-2004 earthquake


IPGP - Campus Jussieu


Séminaires Géodésie et gravimétrie

Salle Orange


IPGP, Equipe de Géodésie et Gravimétrie - IPG Moscow

Résumé : The Earth's gravity field changes with time, following mass redistribution inside the Earth system. In particular, motion of the ground surface and of inner interfaces during an earthquake changes the gravity field in the vicinity of the epicenter. We investigated temporal gravity variations associated with Andaman-Sumatra-2004 earthquake using satellite GRACE gravity data which, unlike GPS, provide a uniform coverage of land and oceanic areas. In addition to the gravity variations caused by the earthquake itself, satellite gravity revealed subsidence in the south-eastern Andaman Sea, which was not documented before. Thus, GRACE allows locked subduction zones to be monitored. Our study shows the importance of complementing seismological and GPS data by satellite gravity data, in order to gain a more complete picture of the deformation associated with large earthquakes. Time variations of gravity also appear to be a promising tool to reveal silent earthquakes (slow aseismic slip events) occurring in subduction zones. It is important, that areas of large stress accumulation can be recognized not only by narrow relatively weak positive geoid anomalies along trench, but also by wider and stronger anomalies in back-arc basins. ------------------------------------------------------------------------ Séminaires de Géodésie et gravimétrie ------------------------------------------------------------------------