Center for Seismic Studies Semiannual Technical Report March-October 1992

• Main Authors: Carter, Jerry, Coyne, John, Grant, Lori, Henson, Anne, Israelsson, Hans, Riviere, Florence, Rhaboy, Vlad
• Other Authors: SCIENCE APPLICATIONS INTERNATIONAL CORP ARLINGTON VA CENTER FOR SEISMIC STUDIES
• Format: Text
• Language: English
• Published: 1992
• Subjects: Seismology; *DATA BASES; *SEISMIC DISCRIMINATION; POLARIZATION; DISTRIBUTION; PARAMETERS; EARTHQUAKES; AZIMUTH; BLAST; MINES(EXCAVATIONS); TREMORS; FILTRATION; BIAS; ARRIVAL; WAVEFORMS; DEPTH; PHASE; IDENTIFICATION; GROUND TRUTH DATA BASES; DATASETS; IMS(INTELLIGENT MONITORING SYSTEM); Kola Peninsula; kola peninsula
• Online Access: http://www.dtic.mil/docs/citations/ADA269380; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA269380

The first chapter of this report describes a ground-truth database that is being constructed for discrimination research. It includes waveforms, source parameters, and arrival information for earthquakes, mine blasts, and mine tremors at regional distances with magnitudes between 2 and 4. The next four chapters are devoted to improving the performance of the IMS. A new method of azimuth estimation using regional knowledge of azimuth bias is proposed that also decreases the scatter in azimuth estimates. An examination of S-phases at near-regional distances in refraction profiles shows complexity that is not accounted for in the IMS that leads to large event mis-locations (20 km in one case). It is also demonstrated that RMS Lg magnitudes are more stable magnitude estimators than the current IMS magnitude estimators. The next chapter describes the results of event identification research for Kola Peninsula events using cluster analysis. Evidence of the method's ability to group events from the same source region (mine) comes from the time distribution of events that comprise a cluster. The final chapter examines the use of polarization filtering to enhance depth phases. Improvement is shown in some cases, but further research is warranted. Ground Truth Database, Azimuth Estimation, Phase Identification, RMS Lg Magnitudes, Event Identification, Depth Phases