Source Analysis of the Crandall Canyon, Utah, Mine Collapse

摘要

On 6 August 2007, a magnitude 3.9 seismic event was associated with the tragic collapse of a Utah coal mine, which ultimately killed six miners and three rescue workers. The event was recorded on the local network of the University of Utah Seismograph Stations and the Advanced National Seismic System (ANSS) operated by the U.S. Geological Survey. In addition, the National Science Foundation Earthscope USArray stations had recently been installed in the region (1). These stations provided good coverage (Fig. 1A) enabling seismic source analysis of the recorded signals, which revealed an unusually shallow depth and anomalous radiation pattern, both contrary to (he expectation for a tectonic earthquake. First-motion polarities from vertical-component records of the seismic event are down, or dilata-tional, indicative of an implosional source (2).