The Norwegian Seismic Array (NORSAR). Phase 3
Abstract
The Norwegian Seismic Array (NORSAR) detection processing system has been operated from 1 October 1984 - 31 March 1985, with an average uptime of 98. 2%. Preliminary evaluation of the real time detection system for the NORESS array has shown an excellent P-wave detection performance at high signal frequencies. Such frequencies are commonly observed for all seismic events at regional distances, and for many teleseismic events especially in Eurasia. Detection of secondary regional phases (Sn and Lg), which is important for the location procedure in the NORESS system, needs further refinement. A newly developed off-line interactive analysis package has been applied to study in detail a NORESS data base of 18 regional events from Western Russia and this study has shown that estimates of azimuth and phase velocity using F-k anlaysis are quite strongly dependent on the analysis frequency selected. A newly developed broad-band spectral estimation technique gives promise of more stable estimates. Studies of travel time residuals using GSDN network data for both deep and shallow events have indicated that the reference earth model (PREM) needs to be modified, both with regard to the upper and lower mantle. A study of teleseismic P coda using NORSAR and NORESS data has given evidence to confirm the hypothesis that the coda is composed of on-azimuth P and off-azimuth Lg, the former being due to scattering of Lg to P near the source and the latter being due to scattering to P to Lg near the receiver. A maximum likelihood method to extract azimuth and angle of incidence using 3-component data has been applied to NORESS recordings.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1985
- Accession Number
- ADA163101
Entities
People
- L. B. Loughran
Organizations
- Royal Norwegian Council for Scientific and Industrial Research