Scientists are studying carefully the geology of Yucca Mountain, Nevada, and its surrounding region to determine whether or not spent nuclear fuel and high-level radioactive waste could be isolated safely deep below the mountain's surface. These studies began more than 15 years ago. The studies and analyses that provide information about the potential for earthquakes have now been completed. 1 Engineering analyses are now under way to ensure that repository facilities are designed to mitigate the effects of potential earthquakes.
Earthquakes occur when cracks or fissures in the Earth's surface, called faults, move.
Major trenching programs near Yucca Mountain have studied fault movement during the past two million years. Geologic study of the deposits exposed in these trenches and minerals found in fault zones provided evidence of how frequently and how much faults have moved in the past. It also appears that the potential for earthquake damage to an underground repository is very slight. Experience with earthquakes throughout the world has shown that underground structures can withstand the ground motion generated by earthquakes. And in actual tests at the Nevada Test Site, mine tunnels have withstood ground motion from underground nuclear explosions that are greater than any ground motion anticipated at or near Yucca Mountain.