The 2009 Samoa-Tonga great earthquake triggered doublet

Thorne Lay, Charles J. Ammon, Hiroo Kanamori, Luis Rivera, Keith D. Koper, Alexander R. Hutko

Research output: Contribution to journalArticle

124 Scopus citations

Abstract

Great earthquakes (having seismic magnitudes of at least 8) usually involve abrupt sliding of rock masses at a boundary between tectonic plates. Such interplate ruptures produce dynamic and static stress changes that can activate nearby intraplate aftershocks, as is commonly observed in the trench-slope region seaward of a great subduction zone thrust event1-4. The earthquake sequence addressed here involves a rare instance in which a great trench-slope intraplate earthquake triggered extensive interplate faulting, reversing the typical pattern and broadly expanding the seismic and tsunami hazard. On 29 September 2009, within two minutes of the initiation of a normal faulting event with moment magnitude 8.1 in the outer trench-slope at the northern end of the Tonga subduction zone, two major interplate underthrusting subevents (both with moment magnitude 7.8), with total moment equal to a second great earthquake of moment magnitude 8.0, ruptured the nearby subduction zone megathrust. The collective faulting produced tsunami waves with localized regions of about 12metres run-up that claimed 192 lives in Samoa, American Samoa and Tonga. Overlap of the seismic signals obscured the fact that distinct faults separated by more than 50km had ruptured with different geometries, with the triggered thrust faulting only being revealed by detailed seismic wave analyses. Extensive interplate and intraplate aftershock activity was activated over a large region of the northern Tonga subduction zone.

Original languageEnglish (US)
Pages (from-to)964-968
Number of pages5
JournalNature
Volume466
Issue number7309
DOIs
StatePublished - Aug 19 2010

All Science Journal Classification (ASJC) codes

  • General

Fingerprint Dive into the research topics of 'The 2009 Samoa-Tonga great earthquake triggered doublet'. Together they form a unique fingerprint.

  • Cite this

    Lay, T., Ammon, C. J., Kanamori, H., Rivera, L., Koper, K. D., & Hutko, A. R. (2010). The 2009 Samoa-Tonga great earthquake triggered doublet. Nature, 466(7309), 964-968. https://doi.org/10.1038/nature09214