The Antofagasta 1995 Earthquake : Crustal deformation pattern as observed by GPS and D-INSAR

Abstract

Combinations of different ground and space techniques provide promising tools for the assessment and understanding of Geo-Hazards. We studied the spatially distributed surface deformation related to the 30 July 95, Antofagasta, Chile, subduction earthquake. In order to do this, we applied two space techniques: the Differential Interferometric SAR technique using three sets of ERS-1 SLC data and repeated GPS-measurements in a regional 70-sites' network. Results indicate that: a) co-seismic surface deformation reached values of 90 cm in the vicinity of the epicenter along the coast and values of 10 cm in a distance of 200 km to the epicenter in the direction normal to the trench; b) both the GPS-method and the D-INSAR technique provided highly comparable deformation; c) the co-seismic surface deformation field is fairly homogeneous and shows little perturbations ; d) we are not yet able to distinguish between the long-term secular deformation and the earthquake event triggered deformation. Combining both methods, however, results suggest that where long-term accumulation rates of deformation are apparently high, i.e., in the western part of the investigated area, they must be homogeneously distributed.