Seismic unloading and loading in northern central Chile as observed by differential Synthetic Aperture Radar Interferometry (D-INSAR) and GPS

Abstract

Using data of two GPS campaigns as well as two ERS-1/2 Single Look Complex (SLC) datasets, we studied the distribution of co-seismic and post-earthquake surface deformation of the major (moment magnitude Mw=8.1) Antofagasta (Chile) event of 30 July 1995. Earthquake-related fault dimensions and inter-seismic surface deformation patterns were achieved by comparing results from the GPS and interferometric Synthetic Aperture Radar (SAR) investigations and by applying interpretative forward dislocation modelling. SAR data post-dating the major earthquake suggest a change in deformation directions after the earthquake within the first 50–80 km normal to the Chilean coast and show opposite signs when comparing results of the western part of the study area with those of the eastern part. We propose that this change in direction might be indicative of a superposition of relatively rapid post-seismic slip along a deeper section of the fault zone and/or distributed relaxation of the lower crust/upper mantle and seismic loading along the coastal part of the fore-arc. Assuming that the Antofagasta earthquake ruptured the entire seismogenic interface, we used the derived depth distribution of the interplate fault for the estimation of seismic moment rates. Taking into account the rate and size distribution of teleseismic events from the USGS and recently derived plate convergence rates, we constrained the size of the maximum earthquake and approximated the apparent recurrence intervals of events similar to the Antofagasta event in the area.

Notes

^*[email protected]

Additional information

Notes on contributors

Y. Xia*

*[email protected]