Discrimination Capability for Mining Events in the Altai-Sayan Region of Russia and the Western United States

摘要

As more seismic and infrasound stations and arrays are deployed for nuclear explosion monitoring, catalogs of seismic events contain not only earthquakes, but many types of anthropogenic sources. Mining events are commonly recorded at regional distances by these stations, with the possibility of misidentification, (e.g., a legitimate mining explosion mistaken as nuclear). Additionally, a nuclear explosion could potentially be embedded in a mining explosion and be missed. Different discriminants have been utilized to separate mining events from natural seismicity with varying degrees of success. In this paper we present results of ongoing efforts to test several discriminants (amplitude ratios, time varying spectral analysis, time-of-day analysis, and infrasound) for two active mining regions: the Powder River Basin (PRB) in the western United States and the Altai-Sayan (AS) in Russia. The first phase of work on this contract has focused on using seismic and infrasound data in the PRB as a test bed for developing and assessing different mining explosion discriminants. This work is outlined in detail by Arrowsmith et al. (2006a, 2007). The results obtained indicate that phase amplitude discriminants, which have been found to be successful in separating earthquakes from nuclear explosions, do not separate earthquakes and mining explosions in this region, probably due to a combination of source and path effects. However, a time-varying spectral discriminant developed as part of this project was very successful at identifying the largest types of mining explosions (cast blasts). We also identified infrasound signals from large mining explosions in this region, suggesting good potential for the use of infrasound as an additional discriminant in this region when winds are favorable.