Regional Event Identification Research in Asia
Abstract
Recent event identification efforts at Los Alamos National Laboratory (LANL) include mining event ground-truth data collection in central Asia, and efforts to improve the magnitude and distance amplitude correction (MDAC) discrimination methodology through derivation of Eurasian two-dimensional, regional-phase attenuation models and frequency-dependent Pn and Sn geometric-spreading models for a spherical Earth. Our mining event efforts have identified mines around the former Soviet nuclear test site in eastern Kazakhstan. Using the Kazakh National Data Centre (KNDC) bulletin from 2002 to 2005, and waveforms recorded at station KURK and array MKAR, we combined time-of-day seismic event analysis, waveform cross correlations, seismic event location methods, image analysis, and seismic discrimination methods to identify active mines. Our goal was to tie event clusters with similar waveforms to specific mine sites, and thereby establish ground truth location and event type (earthquake or explosion) information. We found 13 event clusters that are probable mine sites, accounting for 277 individual seismic events. At least 4 of our event cluster locations are within 15 km of open pit mines, clearly visible on low-resolution imagery. All individual members of these clusters occur between 8am and 8pm local time. We presumed 75 local night-time events were earthquakes, and we found that none of these night time events had similar waveforms. Using these probable mining events and the 75 unclustered night events as presumed earthquakes, we tested traditional body-wave discriminants in bands between 0.5 and 12 Hz, and find Lg spectral ratios and Pg/Lg high-frequency ratios show some ability to separate the event populations, but the separation is poor compared with the case of contained, single-charge explosions and earthquakes. The Pg spectral ratio, which has been shown to separate earthquakes and nuclear explosions in central Asia, does not separate mining explosions from ear
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2007
- Accession Number
- ADA520327
Entities
People
- Charlotte A. Rowe
- George E. Randall
- Hans E. Hartse
- Xiaoning Yang
Organizations
- Los Alamos National Laboratory