Theoretical Background

Earthquake detection

Here describe the detection process

Phase association

Here describe the Linker

Amplitude calculation

Computing amplitudes is a prerequisite in order to perform a magnitude estimation later on. Since multiple magnitude estimation methods are provided, each magnitude estimation method requires to compute a corresponding amplitude type. In accordance with the magnitudes methods described in the magnitude estimation section scdetect-cc implements the following amplitude types to be computed:

  • MRelative: Amplitude computed as the ratio between the template waveform and the detection. The approach is outlined by e.g. https://doi.org/10.1038/ngeo697 and https://doi.org/10.1126/sciadv.1601946 and uses the same instrument components as specified by the detector configuration.

  • MLx: Amplitudes required for the amplitude-magnitude regression approach. The implementation follows the approach outlined in https://doi.org/10.1029/2019JB017468 (section 3.3.3 Magnitude Estimation) . Amplitudes used for the amplitude-magnitude regression are so called sensor location RMS (root-mean-square) amplitudes (i.e. the maximum sample-wise RMS regarding the horizontal components for a certain sensor location w.r.t. velocity seismograms).

Amplitudes are calculated once an origin has been declared.

In general, the computation of amplitudes is sensor location dependent. In order to provide dedicated configuration for different sensor locations scdetect-cc makes use of SeisComP’s bindings configuration concept. Note that amplitudes are calculated only:

  • for those sensor locations with bindings configuration available,

  • if the internal waveform buffer still contains the required time window.

The waveform buffer size may be configured using the processing.waveformBufferSize module configuration parameter.

Magnitude estimation

scdetect-cc estimates magnitudes as so called SeisComP station magnitudes ( for further details, please refer to the scmag documentation) . Magnitudes may be estimated for only those sensor locations, the corresponding magnitude types were computed, previously. In accordance with the amplitude types described in the amplitude calculation section, the following magnitude types are available:

  • MRelative: Template-detection ratio based magnitude estimation. Besides, of the corresponding amplitudes to be computed, this particular type requires station magnitudes to be available through EventParameters. (References: https://doi.org/10.1038/ngeo697 , https://doi.org/10.1126/sciadv.1601946)

  • MLx: Amplitude-magnitude regression based magnitude type. Besides, of the corresponding amplitudes to be computed, this particular type requires both amplitudes and station magnitudes to be available by means of EventParameters. Moreover, the approach is based on so-called template families which in fact are groups of related templates. The corresponding template family configuration must be provided by scdetect-cc‘ s --templates-family-json path/to/templates-family.json CLI flag. (References: https://doi.org/10.1029/2019JB017468 (section 3.3.3 Magnitude Estimation))

All magnitude estimation methods listed above are based on the following types of template station magnitudes:

  • MLh: please refer to the SeisComP documentation

  • MLhc: based on MLh, but uses a slightly adjusted relationship (i.e. corrected for near-field observations) and allows for station specific corrections.

NOTE: Magnitudes of type MLhc are preferred over magnitudes of type MLh.

Recall, that template station magnitudes must be available through EventParameters (for further details, please refer to the related section on providing these data products).