Characteristics of Seismic Waves Produced by Surface Mining Operations

摘要

The interest of seismologists in mining explosions has increased substantially with the construction of the International Monitoring System (IMS). The IMS supports the Comprehensive Nuclear Test-Ban Treaty by providing global data coverage from seismic, hydro acoustic, infrasonic, and radionuclide sensors that will detect a host of natural and man-made events at regional ( < 2000 km) distances. Ideally, the recorded data can be used to identify those events that have explosive characteristics and therefore might be clandestine nuclear tests. The regional observations assure the detection of mining explosions, and these must be properly identified to avoid false alarms of the monitoring system. Cooperation with the mining industry, including documentation of the firing programs, provides critical information necessary to characterize the seismograms. The present study contrasts the seismic characteristics of regional seismograms resulting from two quite different mining operations----an iron mine in Minnesota and a coalmine in the Powder River Basin of Wyoming. Data are presented which quantify these differences in terms of previously identified source-type discriminants such as P to Lg ratios and the presence of intermediate (2-12 sec) period surface waves. A linear superposition model that incorporates specific delay-fire and propagation path parameters is used to quantify the observed differences in the seismograms on the basis of differences in travel path and in firing programs.