The Antofagasta 1995 Earthquake: an INSAR Ambiguity Problem

Y. Xia		GeoForschungsZentrum Potsdam xiaye@gfz-potsdam.de http://www.gfz-potsdam.de
Ch. Reigber		GeoForschungsZentrum Potsdam reigber@gfz-potsdam.de http://www.gfz-potsdam.de

Abstract

Using the differential interferometric radar techniques the deformation of the earth's surface can be high-resolution and accurately determined. In the SAGA project (South America Geodynamic Activities) a 70 site geodetic network in the Central Andes is observed once again after 2 years by GPS surveying. There is a displacement of 10 cm in a distance of 200 km, the city Antofagasta shifted even 90 cm westwards. Because an earthquake with m_s=7.6 occurred nearby the city Antofagasta between the two observations (30. July 1995), the seismic deformation can't be separated from aseismic by this two GPS observations. The data from the ERS 1 and ERS 2 synthetic aperture radar instrument acquired in April, July and October 1995 are used to detect the displacement regarding the earthquake by means of the SAR interferometry. The seismic displacement map from D-INSAR gives a simple pattern of the earthquake in the direction of the radar sight line (slant range). On the assumption that the displacement from earthquake has a dominant distribution in the GPS surveying result, the moving of the earth's surface measured by INSAR can be decomposed in vertical and horizontal directions. This paper describes the procedure and it's results.
Keywords: SAR-Interferometry, Earthquake

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry