Preparatory mechanism of Ms8.0 Wenchuan earthquake evidenced by crust-deformation data

Some crustal-deformation data related to the Ms8.0 Wenchuan in 2008,was described and a model that is capable of explaining the observed deformation features is presented.The data include:pre-earthquake uplift in an area south of the epicenter obtained by repeated-leveling measurements;pre-earthquake horizontal deformation by GPS observation during two periods in Sichuan-Yunnan area;vertical deformation along a short cross-fault leveling line in the epicenter area;and co-seismic near-field vertical and horizontal crustal-movement data by GPS.The model is basically "elastic-rebound",but involves a zone between two local faults that was squeezed out at the time of earthquake.