Abstract
In order to reproduce the rupture history of the 2008 Mw8.0 Wenchuan earthquake, the teleseismic and strong‐motion records are adopted. Based on a multiple‐segment, variable‐slip model, the finite fault inversion method is utilized to recover the rupture process. The results are as follows: (1) the rupture duration of the Wenchuan earthquake is about 100 s, and the released seismic moment is 1.24 × 1021 N·m, equal to the moment magnitude Mw8.0. There are 5 asperities on the fault plane, indicating that the earthquake is composed of at least 5 subevents. (2) The slip is mainly distributed on the Beichuan fault, indicating that the Beichuan fault is the main rupture fault. On the southern part of the Beichuan fault, the dislocation underside the Longmenshan area and Hongkou‐Yingxiu near‐surface area is dominated by thrust, and the maximum slip is 11.8 m. Slip between the Yuejiashan and Qingping area is dominated by thrust. On the northern part of the Beichuan fault, the area under Beichuan is dominated by thrust, the slip under Nanba is thrust and strike, near Qingchuan, the slip turns into the strike slip, and the maximum slip is 13.1 m. The dislocation under Bailu is also dominated by thrust, with maximum slip 8.9 m. (3) The rupture of the Wenchuan earthquake is mainly a unilateral rupture to the northeast. The rupture started at the low dip angle part of the Beichuan fault, and after 3 s, it propagated to the Pengguan fault. After 10 s, the largest asperity under Longmenshan in the south section of the Beichuan fault began to break, lasting for about 24 s. Then, the Xiaoyudong fault was triggered by the Pengguan fault, and the bilateral rupture of the high dip angle part of the Beichuan fault started at about 6 s. South section of the Beichuan fault began to break at about 35 s, and at 43 s, 63 s, and 80 s, the rupture extended to Beichuan, Nanba, and Qingchuan areas.
Highlights
The result of released seismic moment is 1.24 × 1021 N·m which is equal to moment magnitude Mw8.0 based on the relation between seismic moment and moment magnitude defined by Hanks and Kanamori [4]) consists of multiple fault segments and produced a complex system of faults along the edge of the Tibetan Plateau in Longmenshan, causing a large number of casualties and property losses. e Longmenshan fault zone, where the seismogenic fault is located, is a complex structure, which consists of four reverse faults [5]
In the process of propagation from the epicenter to the northeast, the rupture passes through several stages, with a fault length of 300 km. e two main rupture zones, which are close to parallel in space, have surface fractures in the BeichuanYingxiu fault (BCF) and Pengguan fault (PGF). e former is 240 km long, while the latter is 72 km long [5,6,7]
It is worth noting that there is a Xiaoyudong fault (XYDF) about 30 km northeast of the epicenter [8], which is sandwiched between the BCF and PGF, about 6 km long (Figure 1). e complexity of the fault is evident in the XYDF area, where obvious bends and discontinuity of the BCF and PGF existed at the intersection
Summary
In the process of propagation from the epicenter to the northeast, the rupture passes through several stages, with a fault length of 300 km. E two main rupture zones, which are close to parallel in space, have surface fractures in the BeichuanYingxiu fault (BCF) and Pengguan fault (PGF). It is worth noting that there is a Xiaoyudong fault (XYDF) about 30 km northeast of the epicenter [8], which is sandwiched between the BCF and PGF, about 6 km long (Figure 1). E complexity of the fault is evident in the XYDF area, where obvious bends and discontinuity of the BCF and PGF existed at the intersection. At the southwest of the intersection, the distance between two faults was 5∼7 km, while at the northeast, it was 7∼15 km [5].
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