【摘要】 利用昌黎、青光、红山等台的地磁绝对观测资料总场F和分量Z，计算了这两个量在平面直角座标系中回归直线的斜率，以及昌黎台各量的中误差和相关系数。结果表明，距震中最近的昌黎台在唐山7．8级地震前斜率出现一明显异常，而且一直持续到地震发生，震后到8月份才恢复正常。距震中稍远的青光台同期也有异常显示，但幅度较昌黎台要小。在其附近11月15日的宁河6．9级地震前又有较突出异常。远离震中的红山台斜率几乎没什么变化。分析认为，昌黎台震前地磁异常，属局部异常，可能是这次强烈地震引起。同时震前异常有由稍远的震源体边缘向震中收缩特征的一些显示。更多还原

【Abstract】 This paper, using the geomagnetic absolute observation data F and Z from Changli, Qingguang and Hongshanstations, computed the slope of regression straight line of these two quantities in a plane right angle coordinate, and the mid-error and correlation coefficient of each quantity of Changli station. The result shows that the slope of Changli station which is the nearest station to the epicenter showed an obvious anomaly before the Tangshan earthquake, which lasted to the occurrence of the earthquake and turned to its normal in August. At the same time,Qingguang station which is further away from the epicenter also ahowed an anomaly, but its amplitude is smaller than that of Changli station, it showed an obvious anomaly before the Ninghe M6. 9 earthquake on Novemberm 15th near the station. The slope o f Hongshan station which is far away from the epicenter showed little changes. By analyses,it is considered that the geomagnetic anomaly of Changli station before the earthquake belonged to regional anomaly, which might be caused by this strong earthquake; meanwhile the anomalies before the earthquake contracted from the focal volume margin to the epicenter.Subjectwords: correlation coefficient ; mid-error ; geomagnetic anomaly更多还原