Völker, David, Geersen, Jacob , Weinrebe, Willi and Behrmann, Jan H. (2012) Tectonic control on submarine mass wasting off Central Chile. [Talk] In: The Lübeck Retreat, Collaborative Research SFB 574 Volatiles and Fluids in Subduction Zones: Climate Feedback and Trigger Mechanisms for Natural Disasters. , 23.-25.05.2012, Lübeck . The Lübeck Retreat: final colloquium of SFB 574; May 23-25, 2012: program & abstracts. ; pp. 35-36 .

Abstract

Submarine landslides are an important but underestimated geological hazard. They can destroy
offshore installations like cables and oil platforms, and generate destructive tsunamis that can
devastate populated shorelines regionally. Off Central and Southern Chile more than 60 submarine
landslides were identified based on a unique bathymetric dataset that was continuously extended and
refined over 16 years and 16 scientific cruises and that now covers ~ 90% of the continental margin.
Despite of the good documentation, still little is known about the mechanisms that caused the
individual slope failure events, about the frequency of such events and their relation to the powerful
earthquakes that happen here each 50-100 years.To investigate the preconditioning and triggering mechanisms for the landslides we combine the highresolution swath bathymetric data set with reflection seismic profiles and sediment-echosounder data.In particular we focus on how the tectonic regime, that significantly varies along-strike, impacts on thetype, shape and frequency of slope failures. Furthermore, we investigate how the direct and instantaneous seismic loading generated by the magnitude 8.8 Maule Earthquake that ruptured partsof the study area on the 27 February of 2010 impacted on the slope stability. Such a comparison is possible as we mapped the rupture area bathymetrically before and shortly after the earthquake. Our results indicate that the spatial occurrence of two groups of landslides - lower slope collapses and failures that affect the entire slope - are closely related to the tectonic segmentation of the forearc, and that the long-time tectonic stress regime is a major factor preconditioning slope failure.
The seismic loading by the Maule earthquake, on the other hand had surprisingly little effect in
triggering km-size submarine landslides, albeit steep slopes, ubiquiteous mass wasting of the past
and extreme vertical acceleration in the rupture area.

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