Seismic-afterslip characterization of the 2010 MW 8.8 Maule, Chile, earthquake based on moment tensor inversion

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Abstract

[1] On February 27th 2010, a MW8.8 earthquake struck the coast of south-central Chile, rupturing ∼500 km along the subduction interface. Here we estimate the amount of seismically-released afterslip (SRA) and the mechanisms underlying the distribution of aftershocks of this megathrust earthquake. We employ data from a temporary local network to perform regional moment tensor (RMT) inversions. Additionally, we relocate global centroid-moment-tensor (GCMT) solutions, assembling a unified catalog covering the time period from the mainshock to March 2012. We find that most (70%) of the aftershocks with MW> 4 correspond to thrust events occurring on the megathrust plane, in areas of moderate co-seismic slip between 0.15 and 0.7 fraction of the maximum slip (Smax). In particular, a concentration of aftershocks is observed between the main patches of co-seismic slip, where the highest values of SRA are observed (1.7 m). On the other hand, small events, MW< 4, occur in the areas of largest co-seismic slip (>0.85 Smax), likely related to processes in the damage zone surrounding the megathrust plane. Our study provides insight into the mechanics of the seismic afterslip pattern of this large megathrust earthquake and a quantitative approach to the distribution of aftershocks relative to coseismic slip that can be used for similar studies in other tectonic settings.

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