The Norwegian Seismic Array (NORSAR).
Abstract
Using a data base of about 170 NORSAR-recorded seismic events at regional distances during the past 15 years, a detailed map of propagation characteristics of short period regional seismic phases has been compiled. Lg shows efficient propagation out to about 20 deg at 1 Hz and 10 deg at 4 Hz over continental shield paths (e.g., to the east ot te array), whereas Sn is the dominant secondary phase for the east of the array), whereas Sn is the dominant secondary phase for paths tha cross significant tectonic features like graben structures and continental margins. THe NORESS on-line detection and location performance have been evaluated both for regional and teleseismic events. A case study of 132 Western Norwar/North Sea events has indicated a detection threshold of M sub L 1.5-2.0 for NORESSS. The NORESS epicentral solutions are in most cases consistent with those provided by the Western Norway seismic network. For one site where a large number of known explosions (36) were processed, the average NORESS location error was 10 km. A statistical study of NORESS detections during Apr-Sep 1985 has shown an average of about 100 detections per day, of which about 20% are teleseismic P phases, about 25% regional p phases and the remaining 55% have slow phase velocities (< 6 km/s) corresponding to secondary phases or possibly noise detections.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1985
- Accession Number
- ADA165243
Entities
People
- L. B. Loughran
Organizations
- Royal Norwegian Council for Scientific and Industrial Research