Tsunami threat in the Indian Ocean from a future megathrust earthquake west of Sumatra

John McCloskey, Andrea Antonioli, Alessio Piatanesi, Kerry Sieh, Sandy Steacy, Suleyman Nalbant, Massimo Cocco, Carlo Giunchi, JianDong Huang, Paul Dunlop

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Abstract

Several independent indicators imply a high probability of a great (M>8) earthquake rupture of the subduction megathrust under the Mentawai Islands of West Sumatra. The human consequences of such an event depend crucially on its tsunamigenic potential, which in turn depends on unpredictable details of slip distribution on the megathrust and how resulting seafloor movements and the propagating tsunami waves interact with bathymetry. Here we address the forward problem by modelling about 1000 possible complex earthquake ruptures and calculating the seafloor displacements and tsunami wave height distributions that would result from the most likely 100 or so, as judged by reference to paleogeodetic data. Additionally we carry out a systematic study of the importance of the location of maximum slip with respect to the morphology of the fore-arc complex. Our results indicate a generally smaller regional tsunami hazard than was realised in Aceh during the December 2004 event, though more than 20% of simulations result in tsunami wave heights of more than 5 in for the southern Sumatran cities of Padang and Bengkulu. The extreme events in these simulations produce results which are consistent with recent deterministic studies. The study confirms the sensitivity of predicted wave heights to the distribution of slip even for events with similar moment and reproduces Plafker's rule of thumb. Additionally we show that the maximum wave height observed at a single location scales with the magnitude though data for all magnitudes exhibit extreme variability. Finally, we show that for any coastal location in the near field of the earthquake, despite the complexity of the earthquake rupture simulations and the large range of magnitudes modelled, the timing of inundation is constant to first order and the maximum height of the modelled waves is directly proportional to the vertical coscismic displacement experienced at that point. These results may assist in developing tsunami preparedness strategies around the Indian Ocean and in particular along the coasts of western Sumatra. (c) 2007 Elsevier B.V. All rights reserved.
LanguageEnglish
Pages61-81
JournalEarth and Planetary Science Letters
Volume265
Issue number1-2
Publication statusPublished - Jan 2008

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tsunami
wave height
earthquake rupture
earthquake
seafloor
simulation
extreme event
bathymetry
subduction
Indian Ocean
hazard
coast
modeling
distribution

Cite this

McCloskey, J., Antonioli, A., Piatanesi, A., Sieh, K., Steacy, S., Nalbant, S., ... Dunlop, P. (2008). Tsunami threat in the Indian Ocean from a future megathrust earthquake west of Sumatra. Earth and Planetary Science Letters, 265(1-2), 61-81.
McCloskey, John ; Antonioli, Andrea ; Piatanesi, Alessio ; Sieh, Kerry ; Steacy, Sandy ; Nalbant, Suleyman ; Cocco, Massimo ; Giunchi, Carlo ; Huang, JianDong ; Dunlop, Paul. / Tsunami threat in the Indian Ocean from a future megathrust earthquake west of Sumatra. In: Earth and Planetary Science Letters. 2008 ; Vol. 265, No. 1-2. pp. 61-81.
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McCloskey, J, Antonioli, A, Piatanesi, A, Sieh, K, Steacy, S, Nalbant, S, Cocco, M, Giunchi, C, Huang, J & Dunlop, P 2008, 'Tsunami threat in the Indian Ocean from a future megathrust earthquake west of Sumatra', Earth and Planetary Science Letters, vol. 265, no. 1-2, pp. 61-81.

Tsunami threat in the Indian Ocean from a future megathrust earthquake west of Sumatra. / McCloskey, John; Antonioli, Andrea; Piatanesi, Alessio; Sieh, Kerry; Steacy, Sandy; Nalbant, Suleyman; Cocco, Massimo; Giunchi, Carlo; Huang, JianDong; Dunlop, Paul.

In: Earth and Planetary Science Letters, Vol. 265, No. 1-2, 01.2008, p. 61-81.

Research output: Contribution to journalArticle

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AU - McCloskey, John

AU - Antonioli, Andrea

AU - Piatanesi, Alessio

AU - Sieh, Kerry

AU - Steacy, Sandy

AU - Nalbant, Suleyman

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AU - Huang, JianDong

AU - Dunlop, Paul

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McCloskey J, Antonioli A, Piatanesi A, Sieh K, Steacy S, Nalbant S et al. Tsunami threat in the Indian Ocean from a future megathrust earthquake west of Sumatra. Earth and Planetary Science Letters. 2008 Jan;265(1-2):61-81.