邢台地震区大地电磁观测与研究

MAGNETOTELLURIC STUDIES IN THE XINGTAI EARTHQUAKE AREA OF EASTERN CHINA

在邢台地震区进行了大地电磁观测,并对该地区电性结构与地震的关系进行了研究.该地区地下电性结构较复杂,电性在纵向及横向都存在着显著的变化.一维结果表明,该地区电性纵向分布可分五层,第三层为高导层,埋深约10—20 km.在地震震源集中区,高导层深度有较大变化.电性横向分布也有明显变化.总体上看,地震区内电阻较高,可是地震并不发生在电阻率最高的地点,而多发生在电性变化较大地段.

Magnetotelluric measurements were carried out in the Xingtai earthquake area to study earthquakes in connection with the conductivity structure in the area. The results indicate that the structure is complicated and the conductivity varies significantly among different locations. One-dimensional inversions give a 5-layer structure and the third layer at the depth from. 10 to 20 km is highly conductive. A considerable change in depth of the conductive layer appears as crossing the earthsuake region. The conductivity also varies laterally. Macroscopically, it is resistive in the earthquake region; but the earthquakes occurred at the location where the resistivity is rather low and its gradient is rather large.