Advanced Systems for Assessing the Performance of Regional Networks

Abstract : As studies are undertaken to collect information on factors affecting regional discrimination in various regions, it will be important to have available a tool for evaluating the performance of discriminants and the seismic networks being used. S-CUBED (under ARPA support) has developed an interactive computer system (called XNICE, for X windows program for Network Identification Capability Evaluation) for performing these assessments. We present detection and identification thresholds computed (under the ARPA contract) by XNICE for body and surface waves. We have focused on events occurring in Europe, Western U.S. and Tibet for which we have regional propagation data and previous regional discrimination studies. The propagation characteristics are calibrated to be compatible with observed magnitude-moment, distance decay rate and dispersion relations. We show identification results based on the ability of networks to determine location and depth, the ability to resolve spectral slopes of regional phases and the ability to find Ms:mb and Mw:ML ratios for earthquakes, overburied and normally buried explosions and quarry blasts. Under a new contract to DoE (which has not been initiated), we will extend both the capabilities and applications of the program beyond the scope of the current project. In particular, we will evaluate network (primarily GSETT stations) identification performance in regions that have been chosen for their relevance to monitoring a CTBT. The program will include an assessment of overall network performance and the performance of standard regional discriminants, as well as assessments of methodologies for extracting discrimination features, new developing discriminants and strategies for improving identification performance.