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Discrimination of Mining Events Using Regional Seismic and Infrasound Waveforms : Application to the Us and Russia
| Content Provider | Semantic Scholar |
|---|---|
| Author | Arrowsmith, Stephen John Arrowsmith, Marie Danielle Hedlin, Michael A. H. Stump, Brian W. |
| Copyright Year | 2006 |
| Abstract | Historically, event characterization has focused on the task of separating earthquakes and explosions. However, with the increasing availability of high-quality regional seismic data, including seismic array data, there is a need to characterize smaller events (mb 3.5 and below). The present challenge of seismic event identification therefore includes the task of identifying mining explosions, which fall within this lower range of magnitudes. The increasing availability of infrasound data, and in particular the advent of the International Monitoring System (IMS) infrasound array, affords new opportunities in the combined use of seismic and acoustic data for the discrimination of mining explosions. As detailed in last year’s report, we have assembled a comprehensive database of earthquakes and mining explosions in three mining regions in the US and in the Altai-Sayan mining region in Russia. By establishing a good working relationship with a large mine operator in Wyoming, we have obtained a detailed ground-truth dataset of explosions in the Powder River basin. By focusing on this region initially, we have developed and tested three types of discrimination algorithms based on high-frequency phase amplitude measurements, spectral content and infrasound. An algorithm for identifying delay-fired mining explosions by exploiting the time-independent spectral modulations produced by such explosions has been developed. This algorithm has been enhanced to make it applicable to seismic arrays. By applying the algorithm to the dataset of earthquakes and explosions at the Pinedale seismic array (PDAR) in Wyoming, it is shown that the use of array data significantly improves the discriminant. In a blind test, the method successfully identifies 97% of the events out of a group of 76 earthquakes and large delay-fired mining explosions (cast blasts). The potential of infrasound for contributing to the event identification scheme is assessed using data from the PDIAR infrasound array in Wyoming, which is co-located with the PDAR array. Acoustic detections at the PDIAR array, generated using an array-based signal detection algorithm, are compared with predicted arrival times of cast blast acoustic signals. Predicted arrival times are based on ground-truth information from the mine, which have been adjusted by seismic observations. For one year of data, over fifty percent of cast blasts are associated with detections during July and August, with significantly fewer detections at other times of year. This result suggests that the use of infrasound has good potential for contributing to our identification scheme, although the potential is possibly seasonally dependent. Amplitude ratios at PDAR have been considered for separating delay-fired mining blasts from nearby earthquakes (within 1,000 km of the Wyoming coal mine). Historically, in other regions, high-frequency P/S ratios have been successful at discriminating these types of events; however, in this region that discriminant fails. We believe this is due to a combination of both path effects (as described in Goforth and Zhou, 2006; Zhou and Stump, 2004) and variability in the source. In order to discover more about the role of source variability in successfully discriminating mining events, current work is designed to minimize the role of path effects by developing regional phase attenuation tomography models of the western US. In order to assess the portability of the various discriminants tested in Wyoming to different regions, the above techniques are being applied to the dataset acquired for the Altai-Sayan region in Russia. Initial results on this effort are presented. 28th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://l2a.ucsd.edu/local/Meetings/2006_SRR/PAPERS/03-01.PDF |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
