Publication Date:
2013-06-06
Description:
Determining factors that limit coseismic rupture is important to evaluate the hazard of powerful subduction zone earthquakes such as the 2011 Tohoku-Oki event (Mw=9.0). In 1960 (Mw=9.5) and 2010 (Mw=8.8) Chile was hit by such powerful earthquakes, the boundary of which was the site of a giant submarine slope failure with chaotic debris subducted to seismogenic zone depth. Here a continuous décollement is absent whereas away from the slope failure a continuous décollement is seismically imaged. We infer that underthrusting of inhomogeneous slide deposits prevents the development of a décollement, and thus the formation of a thin continuous slip zone necessary for earthquake rupture propagation. Thus coseismic rupture during the 1960 and 2010 earthquakes seems to be limited by underthrusted upper plate mass-wasting deposits. More generally our results suggest that upper plate dynamics and resulting surface processes can play a key role for determining rupture size of subduction zone earthquakes. This article is protected by copyright. All rights reserved.
Print ISSN:
0954-4879
Electronic ISSN:
1365-3121
Topics:
Geosciences
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