ITP Prof. LIU Jing and her research group published in Earth and Planetary Science Letters their Wenchuan surface rupture investigations, reporting on the basic features of the rupture and helping unravel the mystery of the devastating May 12 Wenchuan Earthquake.

According to their discovery, the slip is mainly partitioned on two NE-trending faults: pure thrusting on the Pengguan fault (with almost scarps as high as 3.5 m), and on the Beichuan fault (for more than 200 km long with a combination of NW side-up thrusting and dextral component, scarp height locally reaching up to 10 m in maximum near Beichuan). They pointed out that 1) The Wenchuan earthquake is one of the very few reported instances of crustal-scale co-seismic incomplete slip partitioning on parallel thrusts; 2) It is an out-of-sequence thrusting event; 3) Inherited fault zone structures play a role in earthquake dynamic rupture process, by guiding the rupture propagation onto paths of pre-existing, though locally unfavorable fault planes; 4) Cross-cutting slickenside striations observed suggests temporal slip rake rotation up to 50°, indicating low initial stress on some parts of the Beichuan fault prior to the earthquake. They thus called for a re-evaluation of tectonic models anticipating little or no active shortening of the upper crust along this edge of the plateau, and a re-assessment of seismic hazard along potentially under-rated active faults across the densely populated western Sichuan basin and mountains.