ESTIMATION OF EARTHQUAKE SOURCE PARAMETERS USING P AND S-WAVES SPECTRA – CASE STUDY THE 2012 SEISMIC CLUSTER IN SOFIA SEISMOGENIC ZONE
Bulgarian Geophysical Journal, 2020, Vol. 43, DOI: https://doi.org/10.34975/BGJ-2020.43.6
Spectral analysis of seismic waves is one of the most important origin of information for the earthquake sources. In this study are presented P- and S-waves spectra of the MW5.6 Sofia 2012 earthquake seismic sequence. Earthquake source parameters (seismic moment, source radius, stress drop) are estimated applying Brune model. The model has been used extensively and it has been shown that it is in a good agreement with observations from many different tectonic regions and for a large range of magnitudes. The database is compiled using digital data from the Bulgarian Seismological Network – NOTSSI (National Operative Telemetric System for Seismological Information). Displacement spectra are generated for P- and S- waves to estimate some source parameters, such as seismic moment, stress drop, source radius and moment magnitude. The source parameters are estimated for 6 earthquakes: for the main event with moment magnitude MW5.6 and for five aftershocks with magnitude МW in interval 3.4 ÷ 4.5. The stress drop values estimated for P – waves are within the expected range for moderate earthquakes while for the S – waves the stress drop values are several times higher than the expected ones. The strongest aftershocks are characterized with lower than the main event stress drop values.
spectra, stress drop, source radius, seismic moment, Sofia seismogenic zone
Author: Plamena Raykova
Affiliation: National Institute of Geophysics, Geodesy and Geography – BAS, str. Acad. G. Bonchev, bl. 3, Sofia 1113, Bulgaria
How to cite:
Raykova, P. (2020). Estimation of earthquake source parameters using P and S-waves spectra – case study the 2012 seismic cluster in Sofia seismogenic zone. Bulgarian Geophysical Journal, Vol. 43, p. 71-80. https://doi.org/10.34975/BGJ-2020.43.6