Crosshole audiofrequency seismology in granitic rocks using piezoelectric transducers as sources and detectors

Abstract

A borehole-to-borehole seismic system using piezoelectric transducers as active elements has been developed and used to investigate the geology at a test site located near Bell's Corners, Ontario. Preliminary results have shown that clear seismograms can be obtained with the system through 100-140 m of weathered, jointed, or pervasively fractured Precambrian rocks. Strong losses are seen due to random scattering, and in some cases, the presence of fracture zones in the seismic travel path completely blocks the transmission of signals. The results of attenuation experiments in different rock types and across unconformities indicate that the principle of seismic shadow imaging may be a powerful tool in rock mass characterization. Two-dimensional images of the seismic slowness and transparency distributions between two boreholes have been derived using a simple, first-order tomographic reconstruction algorithm. © 1984.