1IPGP - Institut de Physique du Globe de Paris (IPGP, 1 rue Jussieu, 75238 Paris cedex 05 ; Université Paris Diderot, Bât. Lamarck A case postale 7011, 75205 Paris CEDEX 13 - France)
Abstract : Intra-plate deformation and associated earthquakes are enigmatic features on the Earth. The Wharton Basin in the Indian Ocean is one of the most active intra-plate deformation zones, confirmed by the occurrence of the 2012 great earthquakes (Mw>=8.2). These earthquakes seem to have ruptured the whole lithosphere, but how this deformation is distributed at depth remains unknown. Here we present seismic reflection images that show faults down to 45 km depth. The amplitude of these reflections in the mantle first decreases with depth down to 25 km and then remains constant down to 45 km. The number of faults imaged along the profile and the number of earthquakes as a function of depth show a similar pattern, suggesting that the lithospheric mantle deformation can be divided into two layers: a highly fractured fluid-filled serpentinized upper layer and a pristine brittle lithospheric mantle where great earthquakes initiate and large stress drops occur.
https://hal-insu.archives-ouvertes.fr/insu-03579670 Contributor : Nathalie POTHIERConnect in order to contact the contributor Submitted on : Friday, February 18, 2022 - 11:19:53 AM Last modification on : Sunday, February 20, 2022 - 3:32:43 AM Long-term archiving on: : Thursday, May 19, 2022 - 6:40:28 PM
yanfang Qin, Satish C. Singh. Seismic evidence of a two-layer lithospheric deformation in the Indian Ocean. Nature Communications, Nature Publishing Group, 2015, 6, pp. 686-689. ⟨10.1038/ncomms9298⟩. ⟨insu-03579670⟩