Monitoring of Time Dependent Electrical Resistivity by Magnetotellurics

A feasibility study is being made to monitor possible electrical resistivity changes preceding the earthquakes. Numerical calculations, based on dilatancy hypothesis, indicate that the resistivity changes as much as 60 percent can be possible at some of the Southern California sites. Preliminary magnetotelluric measurements in the eight month period indicate that changes in the resistivities greater than 10 percent can be monitored by magnetotelluric measurements. The observed scatter in the magnetotelluric measurements are within the random errors of the estimates, and no major earthquake activity is reported in the vicinity of these sites, during this period.