1976年唐山地震前的重力位二次微商变化

本文介绍了唐山大地震前在北京通县西集地震台用扭秤观测的重力位二次微商变化。这个资料与唐山地震前的重力异常符合得比较好。扭秤测量精度较高，仪器性能稳定，两秤臂的一致性好，它对唐山地震前观测的重力异常是一个很好的旁证和补充。说明唐山地震前的重力变化，尤其是１９７５年的加速上和临震前的得力下降是可信的。西集台第一次观测到与地震孕育过程有关的重力位二次微商异常，这对研究唐山地震的前兆，特别是重力场的变化原

THE SECONDARY DERIVATIVE CHANGE OF GRAVITATIONAL POTENTIAL BEFORE TANGSHAN EARTHQUAKE

In this paper the secondary derivitative change of gravitational potential before Tangshan earthquake observed in Xiji seismic station near Beijing is presented.This change accords with the observational results of mobile gravimetry.It is a very good collateral evidence for the anomaly of gravity because the torsion balance is an instrument with higher precision of measurement,stability preformance and identity of two balance arms.It shows that the gravitational change before Tangshan earthquake,especially rise of gravity in 1975 and decrease of gravity before Tangshan earthquake,is believable.The secondary derivitive change of gravitational potential relative to the earthquakes was observed in the torsion balance station at Xiji.It is helpful to study the precursors of Tangshan earthquake,especially to study the cause of gravitational field change.