广东及邻区地震前地磁变化和异常判别指标

The geomagnetic variation and the index of distinguishing anomaly before earthquake in Guangdong and its vicinitys

应用差值、相关、地磁特征线以及地磁加卸载响应比等方法、分别计算了 广东、海南、广西３个台的地磁资料，寻找适用于本区的地磁分析预报方法及地震异常 判别指标。结果表明，当参量超过１．５倍均方差时为异常；异常出现半年内在异常台站 附近（距离小于 ２５０ ｋｍ范围内）发生地震；若两个台站同时出现异常则未来地震将可能 大于６级。在单台分析法中，地磁特征线法和加卸载响应比法效果较好。用特征线法， 当广州台特征线参数Ｋ≤－０．１７为异常，异常出现１～６月内将发生较强地震，其概率为 ６６．７％；用加卸载响应比法，当广州台Ｐ（ｚ）≥２．５时，１周～９个月内可能发生较强地 震，对应率为６０％。震例分析表明，用上述方法提取的震磁中期异常时间一般不超过９ 个月。

To search for the geomagnetic prediction method and the index of distinguishing anomalies, which are suitable for this area, the observational data of 3 geomagnetic stations located in Guangdong, Hainan and Guangxi has been analyzed in different methods such as the difference method of Z between two stations, the correlation method, the characteristic line method, the load and unload response ratio, etc. The result shows that observation data is considered as anomaly if the parameter is over 1.5 times of main square deviation, earthquake will occur around the station within half year, the coming earthquake with M > 6 will occur when the anomaly appeared at two stations. For distinguishing geomagnetic anomaly based on the data of single station, the characteristic line method and the load and unload response ratio method are more effective. The parameter with K = - 0. 17 is considered as anomaly for Guanzhou station by using the .former one, and earthquake will occur with the probability 66.7% in 6 months after anomaly appears; Using the latter one, if P(z) = 2.5 at Guangzhou station, moderate or strong earthquake will occur with the probability 60% in 9 months. The duration time of the seismomagnetic anomaly distinguished in above methods is no more than 9 months, which is the medium - short term anomaly.