Co-seismic ruptures of the 12 May 2008, M-s 8.0 Wenchuan earthquake, Sichuan: East-west crustal shortening on oblique, parallel thrusts along the eastern edge of Tibet
| 作者: |
Liu-Zeng, J., et al. |
| 期刊名称: |
Earth and Planetary Science Letters |
| 发表年度: |
2009 |
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286 |
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3-4 |
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355-370 |
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| 全文链接: |
http://dx.doi.org/10.1016/j.epsl.2009.07.017 |
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| 摘要: |
The M-s 8.0, Wenchuan earthquake, which devastated the mountainous western rim of the Sichuan basin in central China, produced a surface rupture over 200 km-long with oblique thrust/dextral slip and maximum scarp heights of similar to 10 m. It thus ranks as one of the world's largest continental mega-thrust events in the last 150 yrs. Field investigation shows clear surface breaks along two of the main branches of the NE-trending Longmen Shan thrust fault system. The principal rupture, on the NW-dipping Beichuan fault, displays nearly equal amounts of thrust and right-lateral slip. Basin-ward of this rupture, another continuous surface break is observed for over 70 km on the parallel, more shallowly NW-clipping Pengguan fault. Slip on this latter fault was pure thrusting, with a maximum scarp height of similar to 3.5 m. This is one of the very few reported instances of crustal-scale co-seismic slip partitioning on parallel thrusts. This out-of-sequence event, with distributed surface breaks on crustal mega-thrusts, highlights regional, similar to EW-directed, present day crustal shortening oblique to the Longmen Shan margin of Tibet. The long rupture and large offsets with strong horizontal shortening that characterize the Wenchuan earthquake herald a re-evaluation of tectonic models anticipating little or no active shortening of the upper crust along this edge of the plateau, and require a re-assessment of seismic hazard along potentially under-rated active faults across the densely populated western Sichuan basin and mountains. (C) 2009 Elsevier B.V. All rights reserved.
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