The 2008 Wenchuan earthquake, Mw 7.9, ruptured the Longmenshan fault zone at the eastern margin of Tibetan Plateau and formed a 240-km-long surface rupture zone along the Yingxiu-Beichuan fault and an additional 70-km-long surface rupture zone along the Guanxian-Jiangyou fault. Some authors published its repeated recurrence behavior along the preexistent fault trace. Here, we use RTK surveying of alluvial terrace sequence and excavation of the trench across the surface rupture in Qipanshi Village, Qingping Town and find that the vertical offsets of terraces and sediment in the trench are equivalent to the 2008Wenchuan earthquake (∼3 m) in situ which proves that it was possibly a newly born rupture and did not follow the preexistent fault line. Qipanshi Village is located in the jog of the Yingxiu-Beichuan fault. The strain energy accumulated in the jog zone due to different movement of the faults of tow sides, might be focused on the soft interlayer of carbonaceous shale in the north of Qianpanshi and the Wenchuan earthquake triggered the release of strain energy and formed the new surface rupture. This study may be significant in understanding the detailed rupture process of Wenchuan earthquake and selecting the excavation location of paleo earthquake study.
On May 12, 2008, a great earthquake (Mw7.9) awoke the seemingly sleeping Longmenshan fault zone at the eastern margin of the Tibetan Plateau. This catastrophe caused millions of landslides and the loss of thousands lives and a huge property (Zhang et al., 2008). Post-earthquake field investigations indicate that the earthquake generated a 240-km-long surface rupture zone along the Yingxiu- Beichuan fault (YBF) and an additional 70-km-long surface rupture zone along the Guanxian-Jiangyou fault (GJF) (Hao et al., 2009; Xu et al., 2009a; Xu et al., 2009b).