Mw 8.6 Su matran earthquake of 11 April 2012: Rare seaward expression of oblique subduction

Miaki Ishii, Eric Kiser, Eric L. Geist

Research output: Contribution to journalArticle

40 Scopus citations

Abstract

The magnitude 8.6 and 8.2 earthquakes off northwestern Sumatra on 11 April 2012 generated small tsunami waves that were recorded by stations around the Indian Ocean. Combining differential travel-time modeling of tsunami waves with results from back projection of seismic data reveals a complex source with a significant trench-parallel component. The oblique plate convergence indicates that ~20-50 m of trench-parallel displacement could have accumulated since the last megathrust earthquake, only part of which has been taken up by the Great Sumatran fault. This suggests that the remaining trench-parallel motion was released during the magnitude 8.6 earthquake on 11 April 2012 within the subducting plate. The magnitude 8.6 earthquake is interpreted to be a result of oblique subduction as well as a reduction in normal stress due to the occurrence of the Sumatra-Andaman earthquake in 2004.

Original languageEnglish (US)
Pages (from-to)319-322
Number of pages4
JournalGeology
Volume41
Issue number3
DOIs
StatePublished - Mar 1 2013
Externally publishedYes

ASJC Scopus subject areas

  • Geology

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