Reloca Slide: an similar to 24km(3) submarine mass-wasting event in response to over-steepening and failure of the central Chilean continental slope

Abstract

Reloca Slide is the relict of an similar to 24-km(3) submarine slope collapse at the base of the convergent continental margin of central Chile. Bathymetric and seismic data show that directly to the north and south of the slide the lower continental slope is steep (similar to 10 degrees), the deformation front is shifted landwards by 10-15km, and the frontal accretionary prism is uplifted. In contrast, similar to 80km to the north the lower continental margin presents a lower slope angle of about 4 degrees and a wide frontal accretionary prism. We propose that high effective basal friction conditions at the base of the accretionary prism favoured basal accretion of sediment and over-steepening of the continental slope, producing massive submarine mass wasting in the Reloca region. This area also spatially correlates with a zone of low coseismic slip of the 2010 Maule megathrust earthquake, which is consistent with high basal frictional coefficients.