A preliminary study of the influence of Wenchuan M_S8.0 earthquake on in-situ stress state near Longmenshan fault zone: A case study in Beichuan and Jiangyou areas

In order to investigate the influence of Wenchuan M_S8.0 earthquake on in-situ stress state near the Longmenshan fault zone, hydraulic fracturing measurements in three 200 m-deep boreholes were carried out in Beichuan and Jiangyou areas near the fault zone from Oct. to Dec., 2009, and the distribution of current in-situ stress there at the time more than 1 year after the earthquake was analyzed. Based on the in-situ stress measurements and coseismic fault displacement in the study areas, the distribution of additional stress induced by fault motion was calculated with a linear-elastic finite element simulation, and then distribution of the principal stress at the two boreholes before the earthquake was calculated. Finally, the influence of Wenchuan M_S8.0 earthquake on in-situ stress state in a superficial zone near Longmenshan fault was discussed through comparative analysis.