In Situ Monitoring of Local Seismicity

• Main Authors: Husebye, Eystein S., Fedorenko, Yuri V.
• Other Authors: BERGEN UNIV (NORWAY) INST OF SOLID EARTH PHYSICS
• Format: Text
• Language: English
• Published: 2000
• Subjects: Seismology; Seismic Detection and Detectors; *PRIMARY WAVES(SEISMIC WAVES); NORTHERN EUROPE; ARRAYS; SEISMIC DETECTION; MINING ENGINEERING; SEISMIC DATA; WAVE PROPAGATION; CONFIGURATIONS; EARTH CRUST; SEISMIC WAVES; EPICENTERS; NORWAY; AREA COVERAGE; EARTH MANTLE; SEISMOLOGICAL STATIONS; SECONDARY WAVES; PHASE VELOCITY; SYMPOSIA; MONITORING; FOREIGN REPORTS; SEISMICITY; IMS(INTERNATION MONITORING SYSTEM); Khibiny; Kiruna; Norway; Orleans; Fennoscandia
• Online Access: http://www.dtic.mil/docs/citations/ADA530006; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA530006

An essential element of CTBT IMS monitoring is accurate epicenter locations. Recently, focus is on the IASPEI 1991 travel time tables which are not adequate for global usages due to strong upper mantle velocity variations in many regions. Related problems are network configurations (too few reporting stations) and persistent identification and pickings of secondary phases. For small array records, phase velocities can be estimated via f-k analysis but still differentiations between Pg-, PmP- and Pn-phases and likewise Sn- and Lg-phases remain problematic. In the latter case the issue is whether ray theory is adequate for describing wave propagation in the crustal wave guide. We are considering two approaches to the above problems; namely (i) to analyze existing monitoring performance using NORSAR GBF-bulletin data including use of close-in station records from the Khibiny and (ii) event discrimination in W. Norway. The GFB data cover 1999 and the total no of events were 7793 mainly stemming from Kiruna, Sweden (3544), Khibiny, Kola (956) and Zapolarny, Kola (325). To our surprise, there is no strong correlation between event occurrences and time-of-day nor day-of-week. The only exception here is Kiruna with a strong concentration of explosions at midnight hours. By taking first and second order deliveries of spatial histograms (seismicity plot) it is easy to identify the above mining areas particularly through the curvature plot. The events areal coverage for the respective mining areas amount to an aperture about 1 deg so accuracy is not unreasonable since bulletin production is automated. However, the strongest curvature are found for areas close to specific mine locations so we test this concept on other parts of Fennoscandia like W. Norway in order to locate the many quarries in industrialized areas. Proceedings of the Annual DoD/DOE Seismic Research Symposium (22nd): Planning for Verification of and Compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT) held in New Orleans, Louisiana on 13-15 September 2000. U.S. Government or Federal Rights. The original document contains color images.