A review of the effects of earthquakes on underground mines

The nature and geography of earthquakes is summarized and the effects of earthquakes on underground structures, due both to the causative process, faulting, and the secondary process, shaking, primarily in the continental United States, is reviewed. The principal sources of information are eyewitness reports, as instrumentally derived seismological data have been available for only about 70 years. Reference is made to the results of instrumented studies in mines and data pertaining to mine bumps and rock bursts in mines. The perceptibility and physical effects of earthquakes in mines and underground workings deserve more systematic study than they have received. Severe damage is inevitable when a mine or tunnel intersects a fault along which movement occurs during an earthquake. Mines in the epicentral region of strong earthquakes, but not transected by fault movement, may suffer severe damage by shaking. Mines outside of the epicentral region are likely to suffer little or no damage from a strong earthquake. Other factors being equal, it appears reasonable that the severity of damage due to shaking would probably be least in a mine located in fresh, highly competent rock; somewhat greater damage would probably be expected in a mine in weathered or less competent rock; and the greatest damage would be expected in a mine located in loose unconsolidated or incompetent rock.