Two-dimensional coseismic deformation field of the Sumatra-Andaman earthquake 2004 M w 9.2 derived from synthetic aperture radar observation

Abstract

The Sumatra-Andaman earthquake with moment magnitude (M w = 9.2) was a thrust earthquake that occurred at 00:58:53 Coordinated Universal Time (UTC) on 26 December 2004, with an epicentre off the west coast of Sumatra Island, Indonesia. To estimate the crustal displacement associated with this earthquake, many scientists have been analysing the global positioning system (GPS) data. In this letter, we calculated the horizontal displacement associated with the earthquake using amplitude offset of synthetic aperture radar (SAR) data. Four C-band SAR images acquired by the European Remote Satellite (ERS)-2 SAR instrument were processed to produce single look complex (SLC) images and to obtain the offset displacement between master and slave images. The offset SAR displacement showed maximum displacement in the northern part of Sumatra Island of 4–6 m. We compared the results with GPS observation and synthetic displacement using a fault geometry model. Our result shows a good agreement with the long-span GPS observation and synthetic model deformation in the southern part of location 1 and in the western part of location 2. We show that the amplitude offset measurement can be an alternative method for measuring ground movements when the field observation data and/or GPS data are sparse or not available.