Aseismic zone and earthquake segmentation associated with a deep subducted seamount in Sumatra

Singh, Satish C. and Hananto, Nugroho and Mukti, Maruf and Robinson, David P. and Das, Shamita and Chauhan, Ajay and Carton, Helene and Gratacos, Bruno and Midnet, Stephan and Djajadihardja, Yusuf and Harjono, Heri (2011) Aseismic zone and earthquake segmentation associated with a deep subducted seamount in Sumatra. Nature Geoscience, 4 (5). pp. 308-311. ISSN 1752-0894 EISSN:1752-0908 DOI 10.1038/ngeo1119

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Abstract

The subduction of large topographic features such as seamounts has been linked to plate locking earthquake generation8 and segmentation, as well as crustal erosion at subduction zones. However, the role of subducted features in the generation of megathrust earthquakes has been difficult to discern because traditional imaging techniques are limited to the upper 12 km of the Earth’s crust12, whereas these ruptures initiate at depths of 20–40 km (ref. 13). Here we use a deeply penetrating imaging technique with a low-energy source to identify a seamount 3–4 km high and 40 km wide that has been subducted to a depth of 30–40 km below the Sumatra forearc mantle. We find that the seamount has remained intact despite more than 160 km of subduction, and that there is no seismic activity either above or below the seamount. We therefore conclude that the coupling between the seamount and overriding plate is weak and aseismic. We suggest that the subduction of a topographic feature such as a seamount could lead to the segmentation of the subduction zone, which could in turn reduce the maximum size of megathrust earthquakes in these localities.

Item Type: Article
Uncontrolled Keywords: 2011AREP; IA62;
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Nature Geoscience
Volume: 4
Page Range: pp. 308-311
Identification Number: 10.1038/ngeo1119
Depositing User: Sarah Humbert
Date Deposited: 15 Dec 2011 17:28
Last Modified: 23 Jul 2013 10:03
URI: http://eprints.esc.cam.ac.uk/id/eprint/2281

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