Near-field postseismic deformation along the rupture of 2008 Wenchuan earthquake and its implications
Near-field postseismic deformation along the rupture of 2008 Wenchuan earthquake and its implications
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DOI：
10.1007/s11434-010-3259-4
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发表时间：
2010-08-01
影响因子：
--
通讯作者：
Sun HaoYue
中科院分区：
文献类型：
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作者：
He HongLin;Wei ZhanYu;Sun HaoYue
首次观测到汶川地震板内活动断裂沿线的震后形变，这实际上是一种滑动后的蠕变。为了了解2008年四川中国汶川地震后的近场震后形变，我们比较了不同活动中测得的断层陡坎或挠曲陡坎剖面。结果表明，在19个观测点中，有13个(68%)断崖后退，平均下降约9.7%，5个(26%)断崖无变化，1个(6%)断崖继续抬升，升幅为12.8%。我们观察到的断层陡坎的变化主要是震后近场形变的结果，在浅层发生了滑动。结果表明：除映秀镇附近的西南端存在同震滑动亏损和部分弹性能量残存外，后退(68%)或不变(26%)的断层陡坎由于逆冲而表现出能量平衡或能量亏损，表明在这些能量释放区发生(C)3/4级7级强余震的可能性很小。此外，我们建议，即使已经考虑了侵蚀引起的误差，但在根据断层陡坎位移来评估历史和古地震或滑动速率时，应考虑至少10%的近场震后变形误差。
At first time, we observed the postseismic deformation, which actually is a kind of creep after slip, along the intra-plate active fault associated with the Wenchuan earthquake. To understand the near-field postseismic deformation following 2008 Wenchuan earthquake in Sichuan Province of China, we compared the fault scarp or flexure scarp profiles measured in different campaigns. Our result shows that among total 19 observation sites, on 13 sites (68% of 19) fault scarps fall back with an average about 9.7% decrease; on 5 sites (26% of 19) fault scarps present no change; and on one site (6% of 19) fault scarp continues to uplift with 12.8% increase. The variety of fault scarp we observed results mainly from near-field postseismic deformation, after slip occurred in shallow. Based on our observations, the following are demonstrated: except for the southwestern end near Yingxiu Town where coseismic slip deficit and some elastic energy residue exist there, fall back (68%) or non-changing (26%) of fault scarp shows energy balance or energy deficit due to overthrust, implying that the likelihood of occurrence of strong aftershocks of a (c) 3/4 M7 becomes very small in these energy-released areas. Moreover, we suggest that a minimum of 10% error due to near-field postseismic deformation should be considered when evaluating the magnitude of historic and paleoearthquake or slip rate based on the fault scarp displacement, even though the error caused by erosion has been accounted already.