Study of the Ability of the Magnetotelluric Method to Monitor Earthquakes

Most earthquakes on the Chinese mainland have occurred within the depth range of 10-25 km,which is usually called the seismogenic layer.According to the rule of penetration depth,the precursor of the electric anomaly,which is transferred from the seismogenic layer to the Earth's surface,should be very weak,but the ability to monitor earthquakes can be greatly improved if the field precursor effect is taken into consideration because of expansion of the electric anomaly area.The results of one-and two-dimensional modeling computations are consistent with the observed fact that the apparent resistivity decreases before earthquakes.This provides good evidence for our inference.The corresponding physical mechanism is that the conductivity of the anomaly area may be increased by the rock dilatation and fluid permeation due to the stress effect during the developing process of earthquakes.