本文应用地磁总强度资料,用两台差消除地磁场短周期变化,同时亦削弱了长期变影响,从而使年变呈线性变化。然后采用趋势面法求得剩余长期变地区性改正量。资料处理后,显示唐山大震前可能有一年半以上的异常,变化幅度约10伽马,对台网中其它几个6级左右地震亦有较好的异常反应。 In this paper, the total geomagnetic intensity data is used to eliminate the short-period change of the geomagnetic field by two sets of errors. At the same time, the long-term variation is weakened, so that the annual variation shows a linear change. Then use the trend surface method to obtain the remaining long-term change of regional correction. After data processing, there may be more than one and a half years of anomaly before the Tangshan earthquake, with a variation range of about 10 Gamma. There are also good anomalous responses to several other earthquakes of magnitude 6 in the network.