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Submarine landslides along the North Ecuador - South Colombia convergent margin: Possible tectonic control

Abstract:

A morphometric analysis of submarine landslides on the continental slope of north Colombia - south Ecuador convergent margin provides insights into hazards, including mass movements locations, size of failures and location control. Bathymetric and seismic data acquired in 2005 revealed three distinctive types of locations with the occurrence of potentially tsunamogenic submarine landslides: 1) the erosive margin toe is characterized by three 5-6-km wide and up to 1500m high semi-circular scarps. The toe is also affected by a 35-km long area of linear scarps resulting from the imbrication of successive failures, 2) canyon walls are affected by five up to 500m high scarps, 3) the deformation front exhibits a 50 × 20 km potentially destabilized area characterized by intensive fracturation. All these features are controlled by active tectonics, Slope oversteepening is a key parameter facilitating the onset of slope failure for the two first types, and is associated with 1) seamount subduction, 2) subsidence related to basal erosion of upper plate, and 3) uplift along active tectonic structures. Regarding the third type, the destabilisation area is influenced by the intensive fracturing at the vicinity of a splay fault.