对地磁记录分析的结果显示，大地震前强烈的地磁异常现象反复出现；在震中附近极震区临震前36 h至十几分钟，地磁场的特大异常数值随震级增大而增大。归算到距震中1 km处，Ms=6.0～9.5 级破坏性地震的磁场异常值约为10²～10⁵ nT，异常强度甚至超过地球磁场量级5.5×10⁴ nT。根据其强度特性及时空分布，这种临震前在震中附近的ULF磁场异常，表现为一种“磁间隙喷发”。由此地磁异常的特性，提出利用大地震前短临地磁异常作为预警信号进行防震预警的探讨，由地磁预警突破目前地震预测预报难的现实困境，有望收到

Strong magnetic anomalies repeatedly took place before big earthquakes. Based on geomagnetic record analysis results, we discussed a possible pattern of the magnetic anomalies prior to earthquake. In meizoseismal area or epicenter, in a time period of 36 hours to 10s minutes before earthquake, the exceptional big geomagnetic change increases with the magnitude of earthquake. We calculated that, in a place of 1 km from the epicenter, the magnetic anomaly before destructive earthquakes of Ms 6.0～9.5 can reach to 10²～10⁵ nT(the magnitude of earth's magnetic field is 5.5×10⁴ nT), rather than the magnitude of 101 nT from seismomagnetic effect theories since 1964.From this we speculated the abnormal magnetic ULF near epicenter before earthquake seems to be an "intermittent magnetic eruption" . Accordingly, we proposed that geomagnetic induction earthquake pre-warning can be a new early warning method to surmount hardship in solving the puzzledom of earthquake imminent prediction.

曾小苹（1939— ） ，女，湖南益阳市人，中国地震局地球物理研 究所 研究员，中国地球物理学会天灾预测委员会委员，主要从事地磁学、日地关系、震磁关系、地震预测及临震预警研究工作