We have investigated earthquake source parameters and seismic moment-magnitude relations from 103 regional and local earthquakes with moment magnitude 2.6 to 7.2, which occurred in a distance range from 4.5 to 550 km during 1995–2012 by applying Brune’s seismic source model (J Geophys Res 75:4997–5009, 1970, J Geophys Res 76:5002, 1971) for P- and S/Lg-wave displacement spectra. Considering P- and S-wave data separately, we first studied the empirical dependence of the Fourier spectral amplitudes Ω due to the geometrical spreading and the inelastic attenuation and of the corner frequency, f0, with the epicentral distances, R. We found the distance correction parameters, Re0.0042R and R0.8333e0.00365R for the low-frequency spectral amplitudes and f0 = f0 ′e0.00043R and f0 = f0 ′e0.00044R for the corner frequency at the source, f0, and observed at the station, f0 ′, from P-wave and S-wave spectra, respectively. Applying the distance correction procedure, we determined the source displacement spectrum of P and S waves for each earthquake to estimate the seismic moment, M0; the moment magnitude, MW; the source radius, r; and the stress drop, Δσ. The seismic moments range from 1.06 × 1013 to 7.67 × 1019 N m, and their corresponding moment magnitudes are in the range of 2.6–7.2. Values of stress drop Δσ vary from 0.1 to 44 MPa. It was found that the stress drop increases with the increasing seismic moment in the range of 1013–1016 N m and possibly becomes constant at higher magnitudes, reaching a maximum value of about 40–45 MPa. We demonstrate that the values of the M0 and MW estimated from P-wave and S-wave analysis are consistent and confirmed by the results of waveform inversions, i.e., centroid moment tensor (CMT) solution.
Bibliographical noteFunding Information:
The study was supported by the Earth Sciences and Research Administration, Ministry of Energy and Water, Israel. We thank the reviewers G. Tusa and L. Ottemoller and J. Zahradnik, editor, for useful and constructive comments that significantly improved the manuscript. Some figures in this study were prepared using the GMT program (Wessel and Smith ).
© 2014, Springer Science+Business Media Dordrecht.
- Seismic moment
ASJC Scopus subject areas
- Geochemistry and Petrology