The Norwegian Seismic Array (NORSAR)
Abstract
During this reporting period the Norwegian Seismic Array (NORSAR) detection Processing System operated with and average uptime of 98.2%. A total of 1792 seismic events were reported by NORSAR in the period. 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. The 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 was 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 analysis are quite strongly dependent on the analysis frequency selected. A newly developed broadband spectral estimation technique gives promise of more stable estimates. Studies of travel time residuals using GSDN network data for both deep and shallow events indicated that the reference earth model 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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1985
- Accession Number
- ADA159820
Entities
People
- L. B. Loughran
Organizations
- Royal Norwegian Council for Scientific and Industrial Research