四川地区地震前跨断层数据异常分析

概述四川7.0级以上大震前观测场地的异常情况。在核实2个大震震前异常的基础上,将传统异常判别方法进行汇总。总结近年来针对跨断层监测数据进行分析进而识别异常的方法:原始数据反映的断层活动速率异常以及转折异常。在此基础上,引入小波分析的方法对大震前的异常进行判别。对小波分解得到的两个趋势项进行分析,发现了大震与小波分解项异常的对应性。最后,基于对原始数据和小波分解项的分析,提出利用跨断层数据分析大震前兆的参考意见,为以后的震前异常研究工作提供了基础。

Pre-earthquake Anomaly Analysis of Cross-fault Data in Sichuan

Since cross-fault means have been determined for nearly 40 years, the Sichuan area has accumulated rich observational data. The Sichuan region is an earthquake-prone area and, in recent years, the Sichuan Province experienced the Wenchuan and Lushan earthquakes, which were greater than magnitude 7. These huge earthquakes resulted in a great human casualty toll and property losses. As such, conducting earthquake prediction research has great significance. There have been many studies in this field and some important achievements. In this paper, we provide an overview of Sichuan earthquakes above 7.0 before which site anomalies have been observed. We also summarize the methods with which anomaly conditions were verified prior to the two large local earthquakes. In a recent analysis, an unusual approach involving cross-fault monitoring data was used, in which the authors found the faulting rate to reflect raw-data anomalies that eventually became abnormalities. On this basis, we introduce a wavelet analysis method for determining the presence of abnormality prior to an earthquake. We analyzed two trends in wavelet decomposition entries and found earthquake occurrence to correspond with abnormal wavelet decomposition. Finally, based on our analysis of raw data and wavelet decomposition, we propose the analysis of cross-fault earthquake precursory data as a reference for future research of earthquake abnormalities. In this paper, we statistically analyze horizontal and vertical anomalies greater than those of the M_S7.0 earthquake in Sichuan Province and use wavelet analysis to analyze long-term observation data. We conclude that the cross-fault monitoring data shows good ability to reflect earthquake occurrence. At present, there are many methods for monitoring earthquakes and in recent years, earthquakes have frequently occurred. Our proposed comprehensive method for conducting retrospective earthquake research provides a very useful prediction tool.