Automatic (GBF) bulletin
The bulletins contains UNCHECKED, FULLY AUTOMATIC locations from the NORSAR Generalized Beamforming (GBF) system.
This automatic list is provided as a service for colleagues in Scandinavia and NW Russia. It contains trial epicenters, and must not be used uncritically as a seismic bulletin.
NORSAR GBF system
Generalized Beam Forming (GBF) is a method for automatically grouping and locating seismic arrivals based on theoretical travel times for a grid of points covering a target area
The geographical region covered by GBF is centered at latitude 59N, longitude 20E and extends approximately 25.5 degrees north and south and 16.5 degrees east and west.
The bulletins contain UNCHECKED, FULLY AUTOMATIC locations with both event lines and associated phase lines.
Event origin time with julian dates ( DOY - Day-Of-Year ), i.e., December 31 is 365 (366 in leap-years).
Event latitude (-90 S to 90 N)
Event longitude (-180 W to 180 E)
Azimuth residual. Sum of absolute values of phase azimuth residuals divided by number of phases.
Time residual. Sum of absolute values of phase time residuals divided by number of phases.
Weighted residual: Time residual + 0.25*Azimuth residual
Number of defining phases (uppercase in phase label)
Total number of phases, including associated coda phases (lowercase in phase label)
Number of stations contributing to the event solution.
- APA - Apatity array, Kola, Russia
- ARC - ARCESS array, Norway
- FIN - FINESS array, Finland
- GER - GERESS array, Germany
- HFS - Hagfors array, Sweden
- NRS - NORESS array, Norway
Station-to-event distance (km)
Theoretical station-to-event azimuth (degrees)
- Upper case - defining phase
- Lower case - associated coda phase
Time residual. Observed minus theoretical arrival time.
Observed station-to-event azimuth (degrees)
Azimuth residual. Observed minus theoretical azimuth.
Apparent velocity (km/s).
Amplitude (Quantum units).
Dominant frequency of signal (Hz).
Quality indicator of F-K analysis (1-4)