The 25 October 2010 Mentawai tsunami earthquake ( Mw 7 . 8 ) and the tsunami hazard presented by shallow megathrust ruptures

[1] The 25 October 2010 Mentawai, Indonesia earthquake (Mw 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, lower than 2.4 × 10 found for the 17 July 2006 Java tsunami earthquake (Mw 7.8). The Mentawai event ruptured up‐dip of the slip region of the 12 September 2007 Kepulauan earthquake (Mw 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. Citation: Lay, T., C. J. Ammon, H. Kanamori, Y. Yamazaki, K. F. Cheung, and A. R. Hutko (2011), The 25 October 2010Mentawai tsunami earthquake (Mw 7.8) and the tsunami hazard presented by shallow megathrust ruptures, Geophys. Res. Lett., 38, L06302, doi:10.1029/2010GL046552.