Abstract

The 27 February 2010, M-w 8.8 Maule earthquake ruptured similar to 500km along the plate boundary offshore central Chile between 34 degrees S and 38.5 degrees S. Establishing whether coseismic fault offset extended to the trench is important for interpreting both shallow frictional behavior and potential for tsunami earthquakes in the region. Joint inversion of high-rate GPS, teleseismic body waves, interferometric synthetic aperture radar (InSAR), campaign GPS, and tsunami observations yields a kinematic rupture model with improved resolution of slip near the trench. Bilateral rupture expansion is resolved in our model with relatively uniform slip of 5-10m downdip beneath the coast and two near-trench high-slip patches with >12m displacements. The peak slip is similar to 17m at a depth of similar to 15km on the central megathrust, located similar to 200km north from the hypocenter and overlapping the rupture zone of the 1928 M similar to 8 event. The updip slip is similar to 16m near the trench. Another shallow near-trench patch is located similar to 150km southwest of the hypocenter, with a peak slip of 12m. Checkerboard resolution tests demonstrate that correctly modeled tsunami data are critical to resolution of slip near the trench, with other data sets allowing, but not requiring slip far offshore. Large interplate aftershocks have a complementary distribution to the coseismic slip pattern, filling in gaps or outlining edges of large-slip zones. Two clusters of normal faulting events locate seaward along the plate motion direction from the localized regions of large near-trench slip, suggesting that proximity of slip to the trench enhanced extensional faulting in the underthrusting plate. Key Points The slip distribution of the 2010 Maule earthquake is determinedJoint inversion of seismic, geodetic, and tsunami data resolves the slipLarge slip extends to the trench in two locations along the rupture