Possibility of the Independence between the 2013 Lushan Earthquake and the 2008 Wenchuan Earthquake on Longmen Shan Fault, Sichuan, China

Abstract

Online Material: Figures comparing calculated Coulomb Failure Stress changes. The 20 April 2013 Lushan earthquake, M s 7.0 (China Earthquake Data Center [CENC]) or M w 6.6 (U.S. Geological Survey [USGS]), with 196 people killed, and more than 10,000 injured according to the local government’s official report, was the strongest earthquake after the 12 May 2008, M s 8.0 (CENC) or M w 7.9 (USGS), Wenchuan earthquake in Sichuan province, China. This earthquake occurred in the southwestern part of the Longmen Shan fault zone, which also was the same causative fault zone of the 2008 Wenchuan earthquake (Fig. 1). The epicenter and focal depth of the Lushan earthquake were at 30.308° N, 102.888° E, and 14.0 km, according to the location of USGS (http://comcat.cr.usgs.gov/earthquakes/eventpage/usb000gcdd#summary, last accessed August 2013). The focal mechanism of the Lushan event showed a thrust rupture which was similar to that of the southwestern part of the Wenchuan earthquake rupture (Fig. 1). The slip distribution of the Lushan earthquake was concentrated at the hypocenter, and did not rupture to the surface (Zhang et al. , 2013, 2014). Figure 1. Tectonic background of the Longmen Shan fault zone and its vicinity. The orange solid circles represent epicenter locations of earthquakes with magnitudes greater than 4.0 from 1 January 1980 to 20 April 2013. The black and blue stars represent the epicenters of the Wenchuan and Lushan earthquakes, respectively, and their focal mechanisms are from global CMT. The white‐ and blue‐dashed polygons represent the region for model fitting and background seismicity checking, respectively. The black lines indicate major faults in this region (Zhang et al. , 2003). The relocated aftershock sequences of the Wenchuan and Lushan earthquakes are from Huang et al. (2008) and Fang et al. (2013). The disastrous Wenchuan M s 8.0 earthquake occurred on the same Longmen Shan fault zone, with …