The Mw 7.9, 12 May 2008 Sichuan earthquake rupture measured by sub-pixel correlation of ALOS PALSAR amplitude images

PALSAR L-band spaceborne Synthetic Aperture Radar (SAR) amplitude images are used to map the Sichuan earthquake rupture (China, M-w 7.9, 12 May 2008) and to identify the faults activated by the earthquake. A sub-pixel correlation method is used to retrieve the coseismic displacement field projected into the line of sight of the satellite and the horizontal along-track direction, and to map the surface rupture. The earthquake broke similar to 270 km of the Beichuan fault and similar to 70 km of the Guanxian fault, with a complex thrust-dextral slip mechanism. Along the southwestern part of the rupture, slip seems to be partitioned into a dextral-dominant component on the Beichuan fault and a thrust-dominant component on the Guanxian fault. Dextral slip may also be dominant at the northeastern tip of the Beichuan ruptured fault. Coseismic surface displacements reach on average 3 to 4 m in both measured directions. The SAR rupture mapping has proven complementary to field studies extending the zone of co-seismic displacements and identifying other possible co-seismic rupture strands.