唐山4.2级地震前易县地震台形变异常特征
Earthquake-reflecting Features of Deformation Anomaly at Yixian Seismic Station Prior to the 2016 Tangshan M4.2 Earthquake

针对2010年3月6日唐山4.2级地震，对河北易县台形变观测资料日均值和月均值变化，进行分析。结果显示，在震源形成及演变过程中，震源区周围一定距离存在应力应变敏感点。震前同一台站几套仪器均出现异常或同一观测不同测向同时出现异常，很可能是与地震相关的异常反应，这种群体异常的信度高于单项异常。同一观测手段在不同地震前异常形态也有差异，在分析资料时要注意这种差异，合理提取异常。在地震孕育过程中前兆异常的共性占主导地位，在短临阶段尤为如此。
With respect to the Tangshan, Hebei M4.2 earthquake that occurred on March 6, 2010, in this study, we analyzed the changes in the observed daily and monthly average deformation values recorded at the Yixian seismic station in Hebei Province. Based on our anomaly extraction results, we discuss the ability of the Yixian station to reflect earthquake activity. Our results show that during the formation and evolution of the source, there are stress and strain sensitivity points at a certain distance from the source area. Prior to the earthquake, several instruments at the same station either showed abnormal activity or different aspects of the same observation showed simultaneous abnormality. These anomalies may be related to the M4.2 earthquake and are more credible than the anomalies of single aspects. Anomalies in the same observation indicate that differences may occur prior to different earthquakes. These differences must be carefully considered when analyzing data.