Locations and types of ruptures involved in the 2008 Sichuan earthquake inferred from SAR image matching

Abstract

We have detected detailed ground displacements in the proximity of the Longmen Shan fault zone (LMSFZ) by applying a SAR offset‐tracking method in the analysis of the 2008 Sichuan earthquake. An elevation‐dependent correction is indispensable for achieving sub‐meter accuracy. A sharp displacement discontinuity with a relative motion of ∼1–2 m appears over a length of 200 km along the LMSFZ, which demonstrates that the main rupture has proceeded on the Beichuan fault (BF) among several active faults composing the LMSFZ, and a new active fault is detected on the northeastward extension of the BF. The rupture on the BF is characterized by a right‐lateral motion in the northeast, while in the southwest an oblique right‐lateral thrust slip is suggested. In contrast to the northeast, where a major rupture proceeded on the BF only, in the southwest multiple thrust ruptures have occurred in the southeastern foot of the Pengguan massif.