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The 25 October 2010 Mentawai tsunami earthquake (M w 7.8) and the tsunami hazard presented by shallow megathrust ruptures

2011; American Geophysical Union; Volume: 38; Issue: 6 Linguagem: Inglês

10.1029/2010gl046552

1944-8007

Thorne Lay, Charles J. Ammon, Hiroo Kanamori, Yoshiki Yamazaki, Kwok Fai Cheung, A. R. Hutko,

Geological and Geochemical Analysis

Mentawai, Indonesia earthquake (M w 7.8) ruptured the shallow portion of the subduction zone seaward of the Mentawai islands, off-shore of Sumatra, generating 3 to 9 m tsunami run-up along southwestern coasts of the Pagai Islands that took at least 431 lives.Analyses of teleseismic P, SH and Rayleigh waves for finite-fault source rupture characteristics indicate ∼90 s rupture duration with a low rupture velocity of ∼1.5 km/s on the 10°dipping megathrust, with total slip of 2-4 m over an ∼100 km long source region.The seismic moment-scaled energy release is 1.4 × 10 -6 , lower than 2.4 × 10 -6 found for the 17 July 2006 Java tsunami earthquake (M w 7.8).The Mentawai event ruptured up-dip of the slip region of the 12 September 2007 Kepulauan earthquake (M w 7.9), and together with the 4 January 1907 (M 7.6) tsunami earthquake located seaward of Simeulue Island to the northwest along the arc, demonstrates the significant tsunami generation potential for shallow megathrust ruptures in regions up-dip of great underthrusting events in Indonesia and elsewhere.