The disastrous Wenchuan, Sichuan, earthquake (MS=8.0) on 12 May 2009 ruptured several major thrust faults of the Longmenshan fold-and-thrust belt, along the western margin of the Sichuan Basin. This earthquake produce...The disastrous Wenchuan, Sichuan, earthquake (MS=8.0) on 12 May 2009 ruptured several major thrust faults of the Longmenshan fold-and-thrust belt, along the western margin of the Sichuan Basin. This earthquake produced significant damages of the area, with more than 60,000 of casualties and countless economic losses, and was one of the largest natural disasters ever occurred in the Sichuan Province in history. The earthquake was accompanied by several surface ruptures, including the central rupture (Beichuan fault), the frontal rupture (Pengguan fault), and a shorter Xiaoyudong rupture between the central and frontal ruptures. The frontal rupture, which is part of the Pengguan fault, had predominantly thrust offset. The total length of the frontal rupture is up to 90 km, with a maximum vertical offset between 3 and 4 m. Although it is called the frontal rupture, the structure is not the frontal fault of the system. South of Hanwang Town, the Pengguan fault follows a mountain front-parallel valley, whereas the actual mountain front structure did not rupture during this earthquake. Immediately north of Hanwang Town, on the other hand, the mountain front approximately follows the fault, but the rupture terminated not very far to the north. Uplifted alluvial surfaces, however, indicate that there is still a blind frontal thrust underneath the western margin of the basin. Along the Jing River, widespread and continuous river terraces provide the opportunity to characterize the late Quaternary slip rates of the faults. Furthermore, unique drainage patterns south of the Xiaoyudong rupture suggest that the area behaves distinctively, and the Xiaoyudong rupture may be an independent fault with previous rupture events.展开更多
文摘The disastrous Wenchuan, Sichuan, earthquake (MS=8.0) on 12 May 2009 ruptured several major thrust faults of the Longmenshan fold-and-thrust belt, along the western margin of the Sichuan Basin. This earthquake produced significant damages of the area, with more than 60,000 of casualties and countless economic losses, and was one of the largest natural disasters ever occurred in the Sichuan Province in history. The earthquake was accompanied by several surface ruptures, including the central rupture (Beichuan fault), the frontal rupture (Pengguan fault), and a shorter Xiaoyudong rupture between the central and frontal ruptures. The frontal rupture, which is part of the Pengguan fault, had predominantly thrust offset. The total length of the frontal rupture is up to 90 km, with a maximum vertical offset between 3 and 4 m. Although it is called the frontal rupture, the structure is not the frontal fault of the system. South of Hanwang Town, the Pengguan fault follows a mountain front-parallel valley, whereas the actual mountain front structure did not rupture during this earthquake. Immediately north of Hanwang Town, on the other hand, the mountain front approximately follows the fault, but the rupture terminated not very far to the north. Uplifted alluvial surfaces, however, indicate that there is still a blind frontal thrust underneath the western margin of the basin. Along the Jing River, widespread and continuous river terraces provide the opportunity to characterize the late Quaternary slip rates of the faults. Furthermore, unique drainage patterns south of the Xiaoyudong rupture suggest that the area behaves distinctively, and the Xiaoyudong rupture may be an independent fault with previous rupture events.
