Seismology, the study of ground tremors in the Earth's crust, has been used extensively to monitor earthquakes and other natural phenomena. For the last 20 years, seismology has been used in the mining industry to monitor disturbances in rock caused by underground excavations. In mining, the scale of the recorded seismic activity is several orders of magnitude smaller than in earthquake seismology. Seismic information is used to understand how the rock mass responds to mining activity, in order to predict or characterize the risk potential for larger, more damaging seismic events.