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Title:: The M_S8.0 Wenchuan Earthquake:Precursor Analysis of Fault Deformation

Author(s):: BO Wan-ju; ZHANG Li-cheng; (First Crust Deformation Monitoring and Application Center,CEA,Tianjin 300180,China)

Keywords:: Wenchuan M_S8.0 earthquake; fault deformation; anomaly; prediction

摘要:: 对汶川8.0级地震的断层形变进行了分析,并与唐山地震、丽江地震的大幅度断层形变异常进行了对比,结论如下:(1)汶川地震前耿达水准、唐山地震前宁河水准和丽江地震前永胜水准其异常有相似的特点;(2)孤立的、无旁证的巨形变异常对强震中短期预测可能有着特殊的指示意义,随着形变观测时空采样密度的大幅度提高,有可能获得旁证;(3)巨形变异常的出现虽不能轻易用于预报地震,但也不能作为干扰轻易加以否定;(4)从断层形变统计资料的数量、时空覆盖面考虑,得出的子样统计结果应该是可信的,从已有强震震例的数量考虑,得出的子样统计结果有待随样本的不断增加而获得改进。

Abstract:: We analyze the fault deformation of the Wenchuan M_S8.0 earthquake,and compare it with the deformations caused by the Tangshan and Lijiang earthquakes. We find that the level anomalies are similar at Gengda Station before the Wenchuan earthquake,Ninghe Station before the Tangshan earthquake,and Yongsheng Station before the Lijiang earthquake. These huge-amplitude anomalies are isolated and not supported by other evidences,but they may be especially significant indication of medium- and short-term prediction of strong earthquake. Furthermore,with the spatio-temporal increase of crust deformation observation station,other supports to predict strong earthquake will be found. Therefore,neither could we use huge-amplitude deformation anomaly to predict a strong earthquake at option,nor could we simply consider it as disturbance. From the used data of fault deformation,the statistic samples are great,and the result is credible; but from the number of strong earthquakes,the samples are small,and the statistic result should be improved with increasing number of strong earthquakes in the future.