Identification of Rockbursts and Other Mining Events Using Regional Signals at International Monitoring System Stations

摘要

Rockbursts present some unique challenges for seismic event identification at low-magnitude monitoring thresholds. Teleseismic discriminants, including traditional determination of focal depth and M (sub S)- versus-m (sub b), are not likely to work for these types of sources. Since many rockbursts are small, their identification depends heavily on observations from a few regional stations. This research program is designed to identify rockburst regions with respect to their significance to nuclear test monitoring, assess the capability of prototype International Data Centre (PIDC)/IDC screening procedures for application in rockburst regions worldwide, and determine ways to improve event identification for such mining regions. During the time period from 1995 to 2000, more than 1100 events were reported in the Reviewed Event Bulletin (REB) within 50 km of 43 historical rockburst sites. Most of these had magnitudes in the range 3 to 4. No REB events were located in proximity to 61 other rockburst sites, although small events (below the REB threshold) may be occurring in those areas. Waveform data from regional International Monitoring System (IMS) stations for Reviewed Event Bulletin (REB) events in each rockburst area are being collected and analyzed. For many of these events, we have been able to establish better ground truth information using local and regional seismic bulletins or, in some cases, information reported from the mines or other agencies; and we have been seeking to establish ground truth information for events in more mining areas. This ground truth information is valuable for event location (as some of the small events are significantly mislocated) and in some cases for identifying event source mechanisms, which permits better understanding of signal variability. We have been carefully analyzing the regional signal characteristics for REB events from several of the more active rockburst areas.