试论大地电磁测深法在地震前兆探索中的进一步应用

THE FURTHER APPLICATION OF MAGNETOTELLURIC SOUNDING IN THE PROBE OF EARTHQUAKE PRECURSORS

从大地电磁测深理论分析和实际资料数字试验出发,我们探讨了有关提高大地电磁测深法监测深部电性变化前兆效能的某些问题.研究结果表明,在所定义的几种大地电磁视电阻率中,尚未加以利用的阻抗实部视电阻率具有某些独特的优点,可能成为监测深部电性变化的一个较好的参数指标;应根据各记录道误差的分配,计算过程误差的传播和累加对不同大地电磁响应函数产生不同的影响,选择相对精度较高的参数作为主要监测参量;而识别深部电性变化的多参数综合判别方法应是基本的分析方法.实际观测到的反映地震前兆的某些大地电磁资料证实了上述论证.

On the basis of the MTS theoretical analysis and numerical test of the measured data,some problems on the enhancement of the effect of monitoring earthquake precursors through measurement of deep electrical variations by the MTS method is discussed. The obtained results show that of the several defined MT apparent resistivities,the still unused apparent resistivity,the real part of the impedance has some unique advantages and can possibly become a better parameter for monitoring the deep electrical variation as an earthquake precursor. It is necessary to select the parameters having highter relative precision as the main parameters to be monitored on the basis of the analysis of various effects on the MT response functions,which result from the error distribution in different channels,the error propagation and accumulation in the computation process. The synthetic judgement method with multi-parameters is the basic method to distinguish the deep electrical variations as an earthquake precursor. The above mentioned conclusion is justified by some observed MTS data reflecting earthquake precursors.