GeoPhysical Research Letters
Mahesh N. Shrivastava 1,2; Gabriel González 1,2; Marcos Moreno 3; Mohamed Chlieh 4; Pablo Salazar 1,2; C. D. Reddy 5; Juan Carlos Báez 6; Gonzalo Yáñez 1,7; Juan González 1,2; and Juan Carlos de la Llera 1,7.
1 National Research Center for Integrated Natural Disaster Management, Santiago, Chile
2 Departamento de Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
3 Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany
4 Geoazur, Université de Nice Sophia-Antipolis, OCA, IRD, CNRS, Valbonne, France
5 Indian Institute of Geomagnetism, Mumbai, India
6 Centro Sismológico Nacional, Universidad de Chile, Santiago, Chile
7 Escuela de Ingeniería, Pontificia, Universidad Católica de Chile, Santiago, Chile
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 8 m, 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 0.50 m 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.