Automatic (GBF) bulletin
The bulletins contains UNCHECKED, FULLY AUTOMATIC locations from the NORSAR Generalized Beamforming (GBF) system.
Warning
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 parameters:
Origin time
Event origin time with julian dates ( DOY - Day-Of-Year ), i.e., December 31 is 365 (366 in leap-years).
Lat
Event latitude (-90 S to 90 N)
Lon
Event longitude (-180 W to 180 E)
Azres
Azimuth residual. Sum of absolute values of phase azimuth residuals divided by number of phases.
Timres
Time residual. Sum of absolute values of phase time residuals divided by number of phases.
Wres
Weighted residual: Time residual + 0.25*Azimuth residual
Nphase
Number of defining phases (uppercase in phase label)
Ntot
Total number of phases, including associated coda phases (lowercase in phase label)
Nsta
Number of stations contributing to the event solution.
Netmag
Network Magnitude.
Phase parameters:
Sta
Station code
- 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
Dist
Station-to-event distance (km)
Az
Theoretical station-to-event azimuth (degrees)
Ph
Phase type
- Upper case - defining phase
- Lower case - associated coda phase
Time
Onset time
Tres
Time residual. Observed minus theoretical arrival time.
Azim
Observed station-to-event azimuth (degrees)
Ares
Azimuth residual. Observed minus theoretical azimuth.
Vel
Apparent velocity (km/s).
Snr
Signal-to-noise ratio.
Amp
Amplitude (Quantum units).
Freq
Dominant frequency of signal (Hz).
Fkq
Quality indicator of F-K analysis (1-4)
Pol
Polarization indicator.
Arid
Arrival ID.
Mag
Phase magnitude.