Techniques and instruments used to detect instability in rock masses around underground mines have been refined and applied to the detection of instability in rock slopes. From the number and magnitude of the acoustic emissions in the rock mass, engineering estimates of slope instability can be made. The electronic apparatus has advanced from early tube-type circuitry to solid-state circuitry capable of amplifying the output of accelerometers, velocity gages, and pressure gages used to detect acoustic emissions (rock noises). Some of the techniques, instruments, and results at four open pit mines are described. The results of these studies show that the techniques can be used to predict failure, monitor the progress of the failure, and provide evidence that earthquakes can affect the stability of a pit wall.
Ch. 16 in Development in Geotech. Eng., V. 2, No. 14B, 1979, PP. 577- 593