山东省定点形变倾斜观测异常指标研究

在研究我省形变台多年观测资料的基础上，提取各台各套仪器的正常变化形态及干扰形态，对山东菏泽５．９级、大同６．１级、南黄海５．３级等地震前的异常特征进行了分析、总结。 结果认为，当各台倾斜仪出现打破以往年变正常规律的形态及γ因子超出二倍中误差时，即可视为异常出现。当趋势异常或γ因子出现转折、大幅度波动时，即可视为进入短期阶段，应注意未来１个月左右地震发生的可能，矢量方向大致指向或背向震中。在进入短期

ANOMALY INDEX STUDY OF FIXED DEFORMATION MEASUREMENT IN SHANDONG PROVINCE

On the basis of studying many year data observed in Shandong Province, The forms of normal variation and disturbance have been obtained Anomaly features before earthquakes of Heze M5 9, Datong M6 1 and South China Sea M5 3 have been analyzed and summarized The results show that it can be taken as anomaly when unusual annual variation appears and factor surpasses two times of median error It can be looked as entering short term stage when tendency anomaly or factor appears turning and big fluctuation In this case it should be noticed that an earthquake could happen in the coming 1 month, and direction of vector points to the epicenter or back epicenter After entering short term anomaly stage anomalies like pulses and steps variation should be paid attention to Especially when earth tide appears the common tilt direction should be noticed Anomaly time usually appears from several hours to several days, even more than ten days in some cases Duration of anomaly is shorter from several minutes to 1 hour Amplitude of anomaly varies with magnitude and epicentral distance