The Wenchuan Ms 8.0 earthquake occurred on the middle section of the Longmen-shan thrust belt, along the eastern border of the Tibetan Plateau. It ruptured simultaneously along two subparallel imbricated reverse faults, and they are Yingxiu-Baichuan fault and Guanxian-Jiangyou fault, respectively. Inverted results from coseismic displacement data reveal that at the southwest segment of Longmen-shan fault, it is reverse-slip and the direction of the maximum compressional stress is nearly in EW direction. And at the northeast segment of Longmen-shan fault, it is dominated by strike-slip and the direction of maximum principal stress is also nearly in EW direction. Though the two segments of tectonic stress states have different stress regimes, they both indicate that the characteristics of the recent tectonic stress state along the Longmen-shan fault is dominated by near East-West compressional dynamic environment. And this result shows a good agreement with field investigations.
The Wenchuan Ms 8.0 earthquake occurred on the Longmen-shan fault, along the eastern margin of the Tibetan Plateau and this thrust belt strikes about N45°E and dips at 50°-75° toward the northwest. The thrust belt is composed of three subparallel imbricated reverse faults, reaching the surface which are Wanchuan-Maowan fault (also called Back-range fault), Yingxiu-Beichuan fault (also called Central-range fault) and GuanxianJiangyou fault (also called Front-range fault), respectively. Besides the thrust, there is another frontal blind thrust fault (Tang at al., 1993; Chan at al., 2007; Jia at al., 2007; Hubbard at al., 2009; Xu at al., 2009). This great quake ruptured a -300-km-long large fault in the crust (e.g., Ji et al., 2008; Wang et al., 2008; Du et al., 2009) and this fauH has a -200-to 270-km-long surface rupture along the Yingxiu-Beichuan fault on the Longmen-shan mountain (Figure 1) with a maximum displacement amounting to 8.0–10.0 m and 5.0–6.0 m in the vertical and horizontal directions (e.g., Li et al., 2008; Liu et al., 2009; Fu et al., 2009). The Wenchuan earthquake also ruptured the Guanxian-Jiangyou fault on a length of 70–80 km (Figure 1) on the surface with a 2.5–3.5 m maximum displacement in the vertical direction (e.g., Fu et al., 2008; Liu et al., 2009; Ma et al., 2008; Xu et al., 2008; Zhang et al., 2008). Because of the great hazards and disaster caused by this large strong earthquake, it has received much attention of international geosciences and the numerous meaningful results (e.g., Xu et al., 2008; Ji at al., 2008; Wang at al., 2008; Du at al., 2009; Li at al., 2008; Liu at al., 2009; Fu at al., 2008, 2009; Ma et al., 2008; Xu et al., 2008; Zhang et al., 2008; Burchfiel, 2008; Sun et al., 2010; Xie et al., 2009) obtained by scientists and scholars from the world are important to explain the mechanism of Wenchuan earthquake.
