Source parameters of the 2013 Lushan M_S7.0 earthquake and the characteristics of the near-fault strong ground motion

A M_S7.0 earthquake occurred in Lushan County, Sichuan Province of China on 20 April 2013, and the maximum intensity is up to Ⅷ to Ⅸ at Baoxing and Lushan Counties, which are located in the meizoseismal area. This study analyzed the dynamic source process with the source mechanism parameters and empirical relationships, estimated the strong ground motion in the near-fault field based on the Brune's circle model. A dynamical composite source model (DCSM) has been developed to simulate the near-fault strong ground motion with associated fault rupture properties at Baoxing and Lushan, respectively. The results indicate that the frictional undershoot behavior in the dynamic source process of Lushan M_S7.0 earthquake is actually different from the overshoot activity of the Wenchuan M_S8.0 earthquake. Moreover, the predictions of broadband synthetic seismogram for Lushan and Baoxing shows that the strong ground motion simulation is characterized by large peak values, shorter duartions and more hige-frequency contents, which is affected by higer value of effective stess drop and asperity slip distribution on the fault plane.