ML and MW solutions for the BELSHAKE database

This dataset contains local magnitude (ML) and moment magnitude (MW) solutions for earthquakes in the BELSHAKE database recorded by stations of the Belgian seismic network.

It consists of 5 tables in CSV-format and an accompanying TXT file explaining the different fields in each table.

For both ML and MW, there are separate tables for the event solutions and the individual station solutions, from which the former are derived. For ML, there is an additional table with the average station residuals.

For both magnitude types, different estimates are available, which can be extracted based on the corresponding table columns.

• ML: using
  • different ways to calculate ML (ml_method column):
    • cam85: original Belgian ML scale
    • hrf2020: ML scale of the Bensberg network (Germany)
    • powerlaw: recalibrated Belgian ML scale
  • 2 different ways to restitute the waveforms to displacement (restitution_method column):
    • rob: instrument response removal, followed by integration and 2x high-pass filtering (1 Hz, 4 poles)
    • wood_anderson: instrument response removal, followed by simulation of Wood-Anderson instrument (with gain=1)
  • 2 different peak estimation methods (peak_method column)
    • strict_p2p=0: between successive peaks (peak method 1)
    • strict_p2p=1: taking into account intervening gradient changes using a Savitzky-Golay filter with a window length of 0.1 s (peak method 2)
  • different components (comp_code column)
    • Z: vertical component
    • E: east-west component
    • N: north-south component
    • GM: geometric mean of horizontal components

The recalibrated Belgian ML scale is based on fitting the combination (cam85, wood_anderson, strict_p2p=1, Z). The final recalibration corresponds to the combination (powerlaw, wood_anderson, strict_p2p=1, Z).

• MW: using
  • 2 different wave types (wave_type column):
    • P-wave (Z component)
    • SH-wave (T component)
  • 2 different radiation patterns (radiation_pattern column):
    • average
    • based on focal mechanism
  • 2 different geometrical spreading models (spreading_model column):
    • 1/R
    • segmented (piecewise continuous powerlaw model, segmented in log space)

The final adopted value in the BELSHAKE database is the weighted average of the combinations (P, average, 1/R) and (SH, average, segmented).