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.