期刊
EARTH AND PLANETARY SCIENCE LETTERS
卷 286, 期 3-4, 页码 355-370出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.epsl.2009.07.017
关键词
Wenchuan earthquake; Longmen Shan thrust belt; Tibetan plateau; surface rupture; co-seismic slip partitioning; out-of-sequence thrusting earthquake
资金
- Chinese Academy of Sciences [KZCX2-YW-134]
- National Science Foundation of China [40672141, 40625008]
- MOST
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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