Submarine mass wasting off Southern Central Chile (Part 1): Distribution and possible mechanisms of Holocene-recent slope failure.

Völker, David, Geersen, Jacob, Weinrebe, Reimer Wilhelm and Behrmann, Jan Hinrich (2010) Submarine mass wasting off Southern Central Chile (Part 1): Distribution and possible mechanisms of Holocene-recent slope failure. [Talk] In: SFB 574 Subduction Workshop. , 04.-07.11.2010, Pucón, Chile .

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Abstract

Based on an extensive set of swath bathymetry data that covers about 72% of the Chilean continental margin between 33°S and 43°S, more than 60 submarine mass wasting features were mapped and described. They form a wide spectrum in size and apparent slide mechanism. With the exception of
three Pleistocene super-scale failures, they are small if compared to mass wasting on passive continental margins.
Half of the features are related to active submarine canyons. The collapse of canyon walls impinges on the open slope where thin translational slides detach from discrete horizons. Also, we identified medium-sized (5-25 km3)
blocky slides that affect the lowermost continental slope, and small spoonshaped headscarps of slides, that deliver material into slope basins. A particular feature is Valdes Slide with mass wasting directed landward. We analyse the database to determine the main preconditioning factors for
mass wasting along this densely populated part of the Chilean coast. Major factors are (1) slope undercutting by the incision of erosive submarine canyons, (2) slope oversteepening by active folding and faulting, and (3)
accretionary wedge collapse. A major stratigraphic control on mass wasting may be offshore deposition of volcanic ash fallout. Also fluid seepage from over pressured faults tapping dewatering subducted sediments at depth may
contribute to destabilization of sediments on the continental slope. The role of large thrust earthquakes that affect the region with a historical recurrence time
of ~ 150 y as apparently obvious triggers is discussed in the light of the recent 27-02-2010 Mw=8.5 Maule earthquake.

Document Type: Conference or Workshop Item (Talk)
Keywords: Geodynamics
Research affiliation: OceanRep > SFB 574 > A1
OceanRep > SFB 574
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Date Deposited: 29 Nov 2010 11:25
Last Modified: 23 Feb 2012 06:30
URI: http://oceanrep.geomar.de/id/eprint/10197

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