2009 earthquakes in Sumatra: The use of L-band interferometry in a SAR-hostile environment

Abstract

On September 30, 2009, a major earthquake of magnitude 7.6 occurred near the west coast of Sumatra close to the city of Padang. On October 1 a significant aftershock (magnitude 6.6) occurred 270 km away. The casualties are estimated at 1200. This earthquake comes at a time when the seismic activity in the region is particularly high [1]. The purpose of this paper is to show the contribution L-band interferometry can have in such an event both from the damage assessment perspective and to enable a better understanding of the underlying geological phenomena. The use of interferometry to assess earthquake displacement has been demonstrated a long time ago [2, 3] but mostly used in dry areas. Interferometry processing is a topic well explored [4] for more than a decade. However, its sensitivity to the image condition: baseline, loss of coherence, slopes, atmosphere. . .makes it difficult to use the same process for all images. The region around the Sumatra earthquake is particularly hostile to interferometry: most of the area is covered by dense vegetation, the area is mountainous with steep slopes and the water content of the atmosphere is high. Furthermore, access to this region is difficult which makes spaceborne interferometry more suitable than airborne. As there are currently no tandem missions for spaceborne interferometry, the temporal baselines are usually important: about 30-50 days depending on the orbit cycle. With such long temporal baselines, the loss of coherence is important for the shorter wavelengths (X and C bands). L-band is more promising as the coherence usually remains sufficiently high even in heavily forested areas.

DOI: 10.1109/IGARSS.2010.5654173

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Cite this paper

@inproceedings{Christophe20102009EI, title={2009 earthquakes in Sumatra: The use of L-band interferometry in a SAR-hostile environment}, author={Emmanuel Christophe and Aik Song Chia and Tiangang Yin and Leong Keong Kwoh}, booktitle={IGARSS}, year={2010} }