The Fine Structure of the Subducted Investigator Fracture Zone in Western Sumatra as Seen by Local Seismicity

Lange, Dietrich and Tilmann, Frederik and Rietbrock, Andreas and Collings, Rachel and Natawidjaja, Danny Hilman and Suwargadi, Bangbam W and Barton, Penny J. and Henstock, Timothy J. and Ryberg, Trond (2010) The Fine Structure of the Subducted Investigator Fracture Zone in Western Sumatra as Seen by Local Seismicity. Earth and Planetary Science Letters, 298 (1-2). pp. 47-56. ISSN 0012-821X DOI 10.1016/j.epsl.2010.07.020

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Abstract

The Sumatran margin suffered three great earthquakes in recent years (Aceh-Andaman 26 December 2004 Mw = 9.1, Nias 28 March 2005 Mw = 8.7, Bengkulu 12 September 2007 Mw = 8.5). Here we present local earthquake data from a dense, amphibious local seismic network covering a segment of the Sumatran margin that last ruptured in 1797. The occurrence of forearc islands along this part of the Sumatran margin allows the deployment of seismic land-stations above the shallow part of the thrust fault. In combination with ocean bottom seismometers this station geometry provides high quality hypocentre location for the updip end of the seismogenic zone in an area where geodetic data are also available. In this region, the Investigator Fracture Zone (IFZ), which consists of 4 sub-ridges, is subducted below the Sunda plate. This topography appears to influence seismicity at all depth intervals. A well-defined linear streak of seismicity extending from 80 to 200 km depth lies along the prolongation of closely spaced IFZ sub-ridges. More intermediate depth seismicity is located to the southeast of this string of seismicity and is related to subducted rough oceanic seafloor. The plate interface beneath Siberut Island which ruptured last in 1797 is characterised by almost complete absence of seismicity.

Item Type: Article
Uncontrolled Keywords: 2010AREP; IA60;
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Earth and Planetary Science Letters
Volume: 298
Page Range: pp. 47-56
Identification Number: 10.1016/j.epsl.2010.07.020
Depositing User: Sarah Humbert
Date Deposited: 23 Jun 2010 11:22
Last Modified: 23 Jul 2013 09:57
URI: http://eprints.esc.cam.ac.uk/id/eprint/1414

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