A high-resolution, time-variable afterslip model for the 2010 Maule Mw = 8.8, Chile megathrust earthquake

•Continuous GPS maps the post-seismic subduction interface in unprecedented detail.•Cumulative afterslip is formed from pulsing, non-migrating, slip patterns.•Static stress transfer only seems to trigger the larger aftershocks.•Plate interface mechanics interpreted from pre-, co-, and post-seismic kinematics.

The excellent spatial coverage of continuous GPS stations in the region affected by the Maule Mw = 8.8 2010 earthquake, combined with the proximity of the coast to the seismogenic zone, allows us to model megathrust afterslip on the plate interface with unprecedented detail. We invert post-seismic observations from continuous GPS sites to derive a time-variable model of the first 420 d of afterslip. We also invert co-seismic GPS displacements to create a new co-seismic slip model. The afterslip pattern appears to be transient and non-stationary, with the cumulative afterslip pattern being formed from afterslip pulses. Changes in static stress on the plate interface from the co- and post-seismic slip cannot solely explain the aftershock patterns, suggesting that another process - perhaps fluid related - is controlling the lower magnitude aftershocks. We use aftershock data to quantify the seismic coupling distribution during the post-seismic phase. Comparison of the post-seismic behaviour to interseismic locking suggests that highly locked regions do not necessarily behave as rate-weakening in the post-seismic period. By comparing the inter-seismic locking, co-seismic slip, afterslip, and aftershocks we attempt to classify the heterogeneous frictional behaviour of the plate interface.