Final Technical Summary 1 April-30 September 1988 (Royal Norwegian Council for Scientific and Industrial Research)

• Main Author: Loughran, L B
• Other Authors: ROYAL NORWEGIAN COUNCIL FOR SCIENTIFIC AND INDUSTRIAL RESEARCH KJELLER
• Format: Text
• Language: English
• Published: 1988
• Subjects: Seismology; Seismic Detection and Detectors; *SEISMIC ARRAYS; *MONITORING; *NUCLEAR EXPLOSION DETECTION; *EARTHQUAKES; COUPLING(INTERACTION); EARTH CRUST; FAULTS(GEOLOGY); NORTH SEA; NORWAY; OFFSHORE; SCALING FACTOR; SIZES(DIMENSIONS); SOLUTIONS(GENERAL); SOURCES; TEST FACILITIES; USSR; NOSAR(Norwegian Seismic Array); NORESS(Norwegian Regional Seismic Array); ARCESS(Arctic Regional Seismic Array); Arctic; Norway
• Online Access: http://www.dtic.mil/docs/citations/ADA210863; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA210863

A study of Lg spectra of NORSAR-recorded explosions from the Shagan River test area near Semipalatinsk, USSR, has shown that the main energy in the Lg wavetrain is confined to the frequency range 0.6-1.0 Hz. There is some evidence of source size scaling effects (i.e; lower dominant Lg frequency for larger events), but the variation is small and appears to be of little significance in RMS LG magnitude estimation. The Lg spectra show no significant differences for events from the two portions of the test site (NE Shagan and SW Shagan). The coupling mode technique for modelling surface wave propagation in 2-D structures presented in previous Semiannual Technical Summaries has been applied to a model of the North Sea Graben, The purpose has been to examine how a large-scale and very strong lateral variation of the crustal structure affects the propagation of the short- period surface wavetrains. A detailed analysis has been made of the recent (August 8, 1988) earthquake offshore Norway. This earthquake is the largest in the region for at least 30 years, with an estimated mb-5.2. Our focal mechanism solution indicates thrust faulting along a NNE-SSW striking fault plane, in response to E-W compressional stress. (JHD)