STABILITY OF A MINED GEOLOGIC REPOSITORY IF SUBJECTED TO SEISMIC EVENTS
The record for anthropogenic underground openings spans a much shorter period of time than for natural openings, but it also attests to remarkable stability even in areas of strong seismicity. Thousands of tombs throughout Europe and the Middle East have been excavated in limestone and volcanic rock. Most of these are older than 2 ka. There are also several kilometers of tunnels in these same two rock types located within areas of strong seismicity, and these have not collapsed in more than 2,500 years. Several compilations of mines and tunnels have documented response to earthquakes during the last 200 years; reports of damage have been minimal. A few reports note heavy damage to surface structures from earthquakes that were not felt by miners working underground. Commonly, when damage has been reported, it was near the portal or in areas of shallow cover. Damage has been reported for tunnels displaced by faulting, but even in these cases, total collapse has not been reported.
The analogue data agree with engineering calculations and strongly suggest that a geologic repository should survive seismic events, especially if tunnels were not driven across capable faults and were located deep underground.