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利用我国及邻近地区(北纬25°—55°,东经105°—145°)14个台站1969—1978年地磁总场强度 T 和垂直分量 Z 绝对观测的年均值时序曲线,经平滑后求得各台逐年的年变率,在空间模式的基础上进而求得 T、Z 年变率随经度、纬度和时间的二次时空分布模式。以此为地磁长期变的时间—空间参考场,审核了昌黎、宝坻、青光、北京和红山五个台站及10个测点截至1978年底绝对测量资料。发现昌黎台地磁垂直分量 Z 自1973年起至1976年系统偏离由参考场计算的拟合曲线,1975年偏差达最大值,幅值为+10r,1976年大震后至1978年底实测值与拟合曲线相当吻合;位于唐山极震区的唐山测点 Z,在1975—1976年系统偏离拟合曲线-12r;位于唐山余震 M_s=6.9震中附近的宁河测点 T 与拟合曲线系统偏差+8r,此测点位于蓟运河断裂之东侧;断裂西侧的东堤头测点T 的系统偏差为-1Or。Z、T 二分量总的异常展布范围与震源区基本相符。距震中位置较远的台站和测点未有超出2σ的偏差。实测值相对于拟合曲线的系统偏离可能是唐山地震的震磁效应。
The annual average time series of absolute observa- tions of geomagnetic total field strength T and vertical component Z from 14 stations in China and adjacent areas (latitude 25 ° -55 ° north latitude and longitude 105 ° -145 ° longitude) from 1969 to 1978 were obtained by smoothing Based on the spatial model, the annual and annual variability of each station can be used to find the secondary spatio-temporal distribution patterns of annual variability of T and Z with time, latitude and time. As a geomagnetic long-term variable time-space reference field, Changli, Baodi, Qingguang, Beijing and Hongshan five stations and 10 measuring points as of the end of 1978 absolute measurement data. It is found that the vertical component Z of Changli station deviates from the fitted curve calculated by the reference field from 1973 to 1976, with the maximum deviation of + 10r in 1975. The measured value after 1976 from the 1976 earthquake to the end of 1978 The coincident curves are quite consistent. The Tangshan measuring point Z located in the Tangshan seismic zone is deviated from the fitted curve from 1975 to 1976 -12r; the Ninghe measuring point T and the fitted curve system deviation located near the epicenter of Tangshan aftershock M_s = 6.9 are + 8r, which is located on the east side of the Jiyunhe fault; the systematic deviation of the T point on the west side of the fault is -1Or. The total anomalous distribution range of Z and T components is basically consistent with the source region. Stations and measuring points far away from the epicenter have not deviated more than 2σ. The systematic deviation of the measured value from the fitted curve may be the seismic magnetic effect of the Tangshan earthquake.