The geometry of the Chilean continental wedge: Tectonic segmentation of subduction processes off Chile

Abstract

Based on high-resolution bathymetry and geophysical observations, the precise continental wedge geometry along the Chileanmargin is analyzed. The data showcomplex patterns in continentalwedge geometry that challenge the most frequently used classification methodology for the convergent margin tectonics. A detailed modeling of the parameters involved in the Non-Cohesive CoulombWedge theory reveals a tectonic latitudinal segmentation of the Chilean offshore subduction zone. This segmentation is characterized by a sequence of broad segments with different basal effective friction coefficient and/or internal fluid pressure conditions, which are limited by the presence of bathymetric oceanic highs, fracture zones and Peninsulas. The results suggest a general increase of the fluid pressure inside the continentalwedge north of 33°S,which is interpreted as a result of amore pervasive fracturing due to tectonic erosion at the base and within the continental wedge. The tectonic segmentation proposed here shows a close spatial relation with the short-term deformation process associated to the coseismic ruptures of large earthquakes in the Chilean margin.