Activity Features of Southeastern Segment of Xianshuihe Fault Zone before and after the Lushan M_S7.0 Earthquake

Under the background that big earthquakes migrated to southeast and the lacking of big earthquakes on the southeastern segment of Xianshuihe faults, cross-fault deformation observation data of three short baselines on southeastern segment of Xianshuihe faults are collected and processed, and the faults activity is analyzed before and after the Lushan earthquake. Our study mainly shows that:(1) the slipping mode on the southeast segment alternates during different period of time. Data of three sites show that the faults activity reversed before and after Lushan earthquake. (2) The slip rate of faults less 1mm/a after Lushan earthquake which is similar to the long term slip rate before earthquake which indicated that the southeast segment was locked or coupled and the strain accumulated. According to "fault slip over seismic cycle" model, time from the last big earthquake on southeastern segment longer than that on northwestern segment is one reason that the slip rates are different on the Xianshuihe faults.