Seismic rupture during the 1960 Great Chile and the 2010 Maule earthquakes limited by a giant Pleistocene submarine slope failure

Authors

  • Jacob Geersen,

    Corresponding author
    1. Collaborative Research Center (SFB) 574 at the GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
    Current affiliation:
    1. University of Southampton, National Oceanography Centre Southampton, Southampton, UK
    • Correspondence: Dr. Jacob Geersen, University of Southampton, National Oceanography Centre Southampton, Waterfront Campus, European Way, Southampton, SO14 3ZH, UK. Tel.: +44 238059 6499; fax: +44 238059 3059; e-mail: j.geersen@noc.soton.ac.uk

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  • David Völker,

    1. Collaborative Research Center (SFB) 574 at the GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
    2. GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
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  • Jan H. Behrmann,

    1. Collaborative Research Center (SFB) 574 at the GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
    2. GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
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  • Dirk Kläschen,

    1. GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
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  • Wilhelm Weinrebe,

    1. Collaborative Research Center (SFB) 574 at the GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
    2. GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
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  • Sebastian Krastel,

    1. GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
    Current affiliation:
    1. Institute of Geosciences, Kiel University, Kiel, Germany
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  • Christian Reichert

    1. BGR, Bundesanstalt für Geowissenschaften and Rohstoffe, Hannover, Germany
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Abstract

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.

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