Formation of Ground Truth Databases and Related Studies and Regional Seismic Monitoring Research

Abstract : The main objective of this project is the formation of databases providing ground truth for regional seismic monitoring research conforming to the latest Center for Monitoring Research (CMR) schema. Selected Calibration Event Bulletin (CEB) events from China, the former Soviet Union (FSU), and North America are reanalyzed using the seismic analysis software program Geotool starting with the Reviewed Event Bulletin (REB) solutions. In order to add a large number of arrivals from regional phases, new waveforms are retrieved and analyzed from available IRIS and other stations. Two sets of location results per event are derived: the first by using only the revised International Data Center (IDC) arrivals, and the second by combining the mostly IRIS and revised IDC data. Analyses of datasets of 70, 80 and 163 CEB events in China, the FSU and North America, respectively, have been completed. Other studies include an analysis of local seismic data from the aftershocks of a 100-ton chemical explosion at the Degelen, Kazakh Test Site on 22 August 1998 (Omega-1). Epicentral locations, based on P-wave arrivals from 14 well-recorded aftershocks, showed all epicenters to lie within 200 meters of ground zero. The result that aftershock locations determined within several days of the detonation time of an explosion can provide a fairly accurate location of ground zero is important for the on-site inspection part of CTBT monitoring. It will therefore be useful to carry out similar studies of aftershocks from other large explosions at this and other test sites.