Crosshole transmission tomography

Abstract

The seismic crosshole technique offers a means to investigate the rock mass between two or more boreholes. Already in 1917 Reginald Fessenden proposed a method to locate ore bodies by crosshole measurements. Fig. 1 is redrawn from his original paper (Fessenden 1917). It is a plan view showing four vertical boreholes and two ore bodies in between. Using a source of seismic energy in one of the boreholes and a detective device in one of the others, the traveltime of waves that have been reflected at or transmitted through the ore bodies can be determined. Combining traveltimes from a number of source/receiver locations at different depths in different boreholes, it should be possible to roughly locate the ore bodies by hand interpretation using elementary geometry. This is the basic idea as outlined by Fessenden. Although the procedure requires a fairly simple medium (only one or two ore bodies, homogeneous surroundings), it points forward to the present use of crosshole tomography.