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Journal: |
Seismological Research Letter 2010 No.6
clicks:971 |
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Title:
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Author:
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Aiming Lin,Zhikun Ren and Gang Rao |
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Adress: |
Institute of Geosciences, Faculty of Science Shizuoka University Shizuoka Ohya 836422-8529, Japan |
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Abstract:
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The Mw 7.9 Wenchuan earthquake, which occurred on 12 May 2008 in the Sichuan region of China (Figure 1), resulted in significant and widespread damage throughout a large area of central and western China. Official estimates of casualties released by the Chinese government include some 70,000 confirmed deaths, plus approximately 374,000 injured and 18,000 missing. Field investigations and seismic data show that the earthquake was triggered by active faults of the Longmen Shan thrust belt, located on the marginal zone between the high Tibetan plateau and the Sichuan basin. A 285-km-long surface rupture zone produced by the earthquake mainly occurred along the pre-existing Yingxiu-Beichuan, Guanxian-Anxian, and Qingchuan faults, which are the main faults of the Longmen Shan thrust belt (Figure 1; Lin, Ren, Jia, and Wu 2009; Lin, Ren, and Jia 2010). Seismic inversion results show a dominantly thrust mechanism for the earthquake, which produced a long co-seismic rupture of up to ∼300 km, which propagated along the NE–SW-trending faults (e.g., China Earthquake Networks Center (CENC) 2008; Chen et al. 2008; Nishimura and Yagi 2008). The maximum co-seismic displacement observed in the field is up to 6.5 m in the vertical (Lin, Ren, Jia, and Wu 2009), with horizontal shortening of 1–3 m (Lin, Ren, and Jia 2010). The rupture length and maximum vertical displacement produced by the Wenchuan earthquake are the largest among all intracontinental thrust-type earthquakes reported to date. Recent trenching investigations have shown that the recurrence interval of M∼8 earthquakes on the active faults that triggered the 2008 Wenchuan earthquake is ∼1,000 years, and that the vertical slip rate along these faults during the late Holocene was ∼2–3 mm/yr (Lin, Ren, Jia, and Miyairi 2010). These previous studies have shown that the main faults of the Longmen Shan thrust belt are … |
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