Regional Signal Characteristics for Use in Screening Seismic Events in Rockburst Areas

摘要

Because of their shallow focal depths, small magnitudes, and often anomalous focal mechanisms, rockbursts may sometimes be difficult to discriminate from other seismic source types. The goals of this research project are to improve CTBT monitoring capability in the vicinity of rockburst areas by carefully analyzing the characteristics of rockburst sources and signals and to develop better regional discrimination techniques for these events using International Monitoring System (IMS) station observations. To accomplish this objective we have collected PIDC data from more than 1000 events in the vicinity (within 50 km) of 35 known historical rockburst sites worldwide for the five year time period starting at the beginning of 1995; 27 other sites of historical rockburst produced no events in the REB during this time period. Based on these REB data, the most active rockburst areas were found to be in Poland, the Kola Peninsula in northern Russia, and South Africa; but rockburst areas in North America, Germany, Tajikistan, and Japan have also been investigated. Although the majority of these events had REB magnitudes in the range 3 is less than or equal to m(b) is less than or equal to 4, very few (n = 5) were 'screened' by the nominal screening procedures at the PIDC. A somewhat larger number (n = 49) were 'not-screened,' but most were 'not considered' or had 'insufficient data' for screening. We have analyzed the PIDC screening results for these rockburst events in detail, and they indicate that teleseismic discrimination procedures are not likely to be effective for screening these rockburst sources. However, there does appear to be some evidence that regional signals recorded by IMS stations from events in these rockburst areas may have differences related to source type.