广西钻孔压磁应力观测异常解释

Analysis on the observation anomaly of piezomagnetic borehole stress in Guangxi

对广西邕宁、灵山钻孔压磁观测资料进行了分析,结果发现,在广西及邻区几次中强地震前,两台钻孔压磁应力显示出一定程度的前兆异常。邕宁、灵山钻孔压磁应力观测曲线出现明显的压应力超差异常,应力测值下降速率较大,震后均显示缓慢的回升过程,特别是北部湾6.1级地震前,两台应力测点出现的方差限(异常限)幅度和时间跨度具有一致性,异常性质均为压性。

We have accumulated some continuous and dependable data since the borehole piezomagnetic stress meters were installed at Lingshan and Yongning seismic stations in Guangxi. The data are analyzed in this paper and the results show that two stress meters had observed some precursory anomalies before several moderately strong earthquakes occurred in Guangxi and its vicinities. The two stress meters recorded the curves of crushing stress obviously abnormal exceeding quadratic square deviation, the values of stress descended rapidly and presented slowly ascending after earthquake, especially before Beibuwan earthquake M 6.1, the amplitudes of quadratic square deviation of extreme value (abnormal value) and time-span had consistency of pressure characteritic.