Abstract:
We analyzed the coseismic and early postseismic deformation of the 2015, Mw 8.3 Illapel
earthquake by inverting 13 continuous GPS time series. The seismic rupture concentrated in a shallow
(<20 km depth) and 100 km long asperity, which slipped up to 8m, releasing a seismic moment of
3.6 × 1021Nm (Mw = 8.3). After 43 days, postseismic afterslip encompassed the coseismic rupture. Afterslip
concentrated in two main patches of 0.50m between 20 and 40 km depth along the northern and southern
ends of the rupture, partially overlapping the coseismic slip. Afterslip and aftershocks confined to region
of positive Coulomb stress change, promoted by the coseismic slip. The early postseismic afterslip was
accommodated ~53% aseismically and ~47% seismically by aftershocks. The Illapel earthquake rupture is
confined by two low interseismic coupling zones, which coincide with two major features of the subducting
Nazca Plate, the Challenger Fault Zone and Juan Fernandez Ridge.
