Preliminary Study of m(b) Bias at Selected Soviet Seismic Stations.

• Main Author: Ryall,Alan S , Jr
• Other Authors: SCIENCE APPLICATIONS INTERNATIONAL CORP ARLINGTON VA
• Format: Text
• Language: English
• Published: 1986
• Subjects: Seismology; *SEISMIC WAVES; *BIAS; USSR; COMPUTATIONS; SITES; GRANITE; RESPONSE; INSTRUMENTATION; CALIFORNIA; EARTHQUAKES; AMPLITUDE; LAKES; TEST FACILITIES; BASINS(GEOGRAPHIC); SIBERIA; SEISMOLOGICAL STATIONS; NEVADA; *M sub b bias; Pacific; Tonga; Yakutsk; Siberia
• Online Access: http://www.dtic.mil/docs/citations/ADA166395; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA166395

Magnitude m sub b was determined for five earthquakes on 25 and 27 May 1980, From recordings at eight Soviet seismic stations on a 4.300 km-long profile from eastern Kazakh to eastern Siberia. The records were hand-digitized, and magnitudes were determined from traces corrected for instrument response as well as the uncorrected traces. Four of the earthquakes were at Mammoth Lakes, California, in the western Great Basin; the fifth was at Tonga in the south Pacific. Magnitude residuals with respect to network-averaged m sub b's listed in the ISC Bulletin were positive for stations at Yakutsk and Seymchan in Siberia, negative for raypaths through the Baikal rift zone, and slightly positive for a station at Semipalatinsk, about 100 km from the East Kazakh test site. A comparison of tabulated magnitude residuals for Soviet seismic stations from previous work of Ringdal (1985), North (1976) and Vanek et al, (1978, 1980) shows excellent agreement with previous work. Recalculation of m sub b for 83 events recorded on granite at the Nevada Test Site provided a determination of magnitude bias ( m sub b =.-0.10 + or - 0.35) for the NTS granite site with respect ISC magnitudes.