判定震前出现的形变显著异常是否与地震相关，是认识地震孕育过程及开展地震预测研究最为重要的基础问题。本文分析了汶川地震前一些显著形变异常特征，发现震前在震中区附近异常较少，而外围则较多。针对其中一些距离震中较远的异常，借助前兆异常与地震震中距、震级间物理统计模型，提出了远距离形变异常与地震关联的判别准则，给出了红柳峡跨断层水准短期异常等与汶川地震之间的联系。最后，结合构造特点讨论了远距离前兆存在的意义。

It is very important to understand the process of earthquake preparation and to carry out earthquake prediction research of the significant abnormal changes which are related to the earthquake. However,no many people have carried out such researches in past. In this paper we analyzed the characteristics of some significant deformation anomalies before Wenchuan earthquake,and found that there are few anomalies near the epicenter before the earthquake,whereas some prominent anomalies are found around the periphery. In order to find the correlation between far field anomalies and earthquake,we proposed a correlation criterion based on a modified statistical-physical model between the precursor duration,epicenter distance and magnitude. A case study of relationship between leveling anomalies along Hongliuxia fault and Wenchuan has been carried out. Finally,we discussed the dynamic meanings of far field deformation precursors.

P315

国家基金委重点项目（41330314）资助