The 2012 Mw 8.6 Sumatra earthquake: Evidence of westward sequential seismic ruptures associated to the reactivation of a N-S ocean fabric - Archive ouverte HAL Access content directly
Journal Articles Geophysical Research Letters Year : 2012

The 2012 Mw 8.6 Sumatra earthquake: Evidence of westward sequential seismic ruptures associated to the reactivation of a N-S ocean fabric

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Abstract

The 11 April 2012 Mw 8.6 earthquake offshore Sumatra is the largest of the rare great intraplate earthquakes of the instrumental era. This major strike-slip event occurred in the diffuse zone of deformation that accommodates differential rotation between Indian and Australian plates. We perform a back projection analysis - calibrated with well-located aftershocks - of short-period teleseismic P-waves recorded by the European array to image the rupture process during the mainshock. In complement, a Love wave analysis is conducted for tracking azimuthal change in the apparent global source duration due to the source spatio-temporal extent. The combined analysis reveals a complex rupture pattern, characterized by three main episodes of energy release, the latest being located 370 km west of the epicenter, on the Ninety East Ridge, with a delay of 120 s. We interpret the 11 April 2012 Mw 8.6 offshore Sumatra earthquake as a complex westward-propagating sequence of dynamically triggered strike-slip fault ruptures, associated to the reactivation of the inherited NNE-striking sea floor fabric. The dynamic triggering mechanism could result from the interaction between transient surface wave stress perturbations and fluids.
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insu-03583338 , version 1 (22-02-2022)

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Claudio Satriano, Eszter Kiraly, Pascal Bernard, Jean-Pierre Vilotte. The 2012 Mw 8.6 Sumatra earthquake: Evidence of westward sequential seismic ruptures associated to the reactivation of a N-S ocean fabric. Geophysical Research Letters, 2012, 39, p. B08409. ⟨10.1029/2012GL052387⟩. ⟨insu-03583338⟩
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