An aseismic slip pulse in northern Chile and along‐strike variations in seismogenic behavior

Abstract

We use interferometric synthetic aperture radar, GPS, and seismic observations spanning 5 to 18 years to reveal a detailed kinematic picture of the spatiotemporal evolution of fault slip in a region corresponding to the 30 July 1995 Mw 8.1 subduction zone megathrust earthquake in northern Chile. In a single area, we document a complex mosaic of phenomena including large earthquakes, postseismic afterslip with a spatial distribution that appears to be tied to variations in coastal morphology, and a completely aseismic pulse that may have triggered a Mw 7.1 earthquake on 30 January 1998. In contrast to simple models of fault slip behavior, this spatial heterogeneity indicates that frictional parameters on the fault do not have a systematic transition with depth and also vary rapidly along strike. The low amount of afterslip from the Mw 8.1 earthquake relative to other similar events suggests that postseismic behavior may be modulated by the amount of sediment subducted.

COSEISMIC DEFORMATION FIELD AND FAULT SLIP DISTRIBUTION OF THE 2015 CHILE Mw8.3 EARTHQUAKE

“…Up to now, three mechanisms of post-seismic deformation have been proposed, which are post-seismic slip(afterslip), postseismic pore elastic rebound and post-seismic visco-elastic relaxation. Short-term (several months or 1-2 years) postseismic deformation is dominated by post-seismic slip, which is consistent with the coseismic displacement in motion direction (Marone, 1991;Mendoza,1994;Pritchard, 2006;Tan Kai, 2005;Vigny, 2011). The post-seismic deformation presented in this paper is confined in a 65km-wide zone along rupture near the coast (Figure4 and Figure5), with complex spatial and temporal changes, which cannot be explained by mechanism of afterslip.…”

Testing stress shadowing effects at the South American subduction zone

“…The rupture length and location for recent strong events were taken from Barrientos & Ward (1990) for the M9.6 1960 Valdivia earthquake, Delouis et al (1997) for the M7.6 1987 earthquake near Antofagasta, Ruegg et al (1996) for the M8.0 1995 Antofagasta earthquake, Pritchard & Simons (2006) for the M9.6 1960 Valdivia earthquake, Chlieh et al (2011) for the M8.4 2001 Arequipa earthquake, the rupture plane of which extends well into our area of investigation, Schurr et al (2014) for the M7.9 2007 Tocopilla earthquake, Yue et al (2014) for the M8.8 2010 Maule earthquake, Geersen et al (2015) and Schurr et al (2014) for the M8.1 2014 Iquique earthquake, and Tilmann et al (2016) for the M8.2 2015 Illapel earthquake. In the case that the rupture length is not constrained by observations, we estimate rupture lengths from the scaling relation of Blaser et al (2010) for dip-slip inter-plate earthquakes.…”

Variability of atmospheric precipitable water in northern Chile: Impacts on interpretation of InSAR data for earthquake modeling

“…The hyper-arid climate of northern Chile, that hosts the 'Atacama Desert', one of the driest deserts on Earth, makes it an ideal setting for the application of InSAR techniques because surface features change little between image acquisitions. Consequently, numerous studies conducted along the central Andean margin have been published in recent years, illustrating the unique capabilities of InSAR to reveal the patterns of crustal deformation related to the earthquake cycle (Chlieh et al, 2004;Pritchard and Simons, 2006). The desert environment might suggest that the errors introduced by water vapor delay are of a minor importance in northern Chile.…”

“…1), one of the most seismically active regions in the world. Monitoring of ground deformation in this region is of great importance as it can provide new insights into the seismic deformation cycle in the Andean margin (Ruegg et al, 1996;Delouis et al, 1997;Klotz et al, 1999;Perfettini et al, 2005;Pritchard and Simons, 2006). The hyper-arid climate of northern Chile, that hosts the 'Atacama Desert', one of the driest deserts on Earth, makes it an ideal setting for the application of InSAR techniques because surface features change little between image acquisitions.…”