PRELIMINARY EXPERIMENTAL RESULT OF A CAPACITANCE-TYPE BORE-HOLE EARTH STRAIN METER

A bore-hole earth strain meter of sensitivity as high as 110-11 (at zero S/N ratio) has been constructed. Experimental result shows it can record seismic waves and strain tides in soft geological formations. It is believed that within at least the frequency band, corresponding to periods from 0.3 second to a few days, the signals thus recorded should contain the true informations of strain variation of the geological formations under stress.