美国科学家们正在地面下挖掘一个5公里深的洞穴,用来作为地下观象台,以便对地质的变化进行探测。这个洞穴的地点是在加州洛杉矶东北大约100公里、距离圣安德列斯断层很近。美国加州的两大城市旧金山和洛杉矶都距离圣安德列斯断层非常近,多年来这两个城市和加州的其它一些比较小的城市都发生过不少次地震。地质学家相信,这个地区将来还会发生更多的地震。圣安德列斯断层是世界上地质学家最注意的地点之一。在过去,研究人员在断层一带安没了许 American scientists are digging a 5-kilometer deep cave under the ground for use as an underground observatory in order to detect geological changes. The location of this cave is about 100 kilometers northeast of Los Angeles, California, very close to the San Andres Fault. The two major cities of California, California, San Francisco and Los Angeles are both very close to the San Andres Fault, with many earthquakes in both and smaller cities in California over the years. Geologists believe there will be more earthquakes in the area in the future. The San Andres Fault is one of the most notable places in the world for geologists. In the past, researchers have been quiet around the fault