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Coseismic and post-seismic signatures of the Sumatra 2004 December and 2005 March earthquakes in GRACE satellite gravity / Isabelle Panet in Geophysical journal international, vol 171 n° 1 (Octobre 2007)  

Public [article]  inGeophysical journal international > vol 171 n° 1 (Octobre 2007) . - pp 177 - 190 Titre : Coseismic and post-seismic signatures of the Sumatra 2004 December and 2005 March earthquakes in GRACE satellite gravity Type de document : Article/Communication Auteurs : Isabelle Panet , Auteur ; Valentin O. Mikhailov, Auteur ; Michel Diament , Auteur ; Fred Pollitz, Auteur ; Geoffrey King, Auteur ; Olivier de Viron, Auteur ; Matthias Holschneider, Auteur ; Richard Biancale, Auteur ; Jean-Michel Lemoine, Auteur Année de publication : 2007 Article en page(s) : pp 177 - 190 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] données GRACE [Termes IGN] géoïde local [Termes IGN] ondelette [Termes IGN] séisme [Termes IGN] subduction Résumé : (auteur) The GRACE satellite mission has been measuring the Earth's gravity field and its temporal variations since 2002 April. Although these variations are mainly due to mass transfer within the geofluid envelops, they also result from mass displacements associated with phenomena including glacial isostatic adjustment and earthquakes. However, these last contributions are difficult to isolate because of the presence of noise and of geofluid signals, and because of GRACE's coarse spatial resolution (>400 km half-wavelength). In this paper, we show that a wavelet analysis on the sphere helps to retrieve earthquake signatures from GRACE geoid products. Using a wavelet analysis of GRACE geoids products, we show that the geoid variations caused by the 2004 December (Mw = 9.2) and 2005 March (Mw = 8.7) Sumatra earthquakes can be detected. At GRACE resolution, the 2004 December earthquake produced a strong coseismic decrease of the gravity field in the Andaman Sea, followed by relaxation in the area affected by both the Andaman 2004 and the Nias 2005 earthquakes. We find two characteristic timescales for the relaxation, with a fast variation occurring in the vicinity of the Central Andaman ridge. We discuss our coseismic observations in terms of density changes of crustal and upper-mantle rocks, and of the vertical displacements in the Andaman Sea. We interpret the post-seismic signal in terms of the viscoelastic response of the Earth's mantle. The transient component of the relaxation may indicate the presence of hot, viscous material beneath the active Central Andaman Basin. Numéro de notice : A2007-673 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/j.1365-246X.2007.03525.x Date de publication en ligne : 01/10/2007 En ligne : https://doi.org/10.1111/j.1365-246X.2007.03525.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102773 [article]