SPECTRAL ANALYSIS OF 12 NOVEMBER 2017 AND 25 NOVEMBER 2018 EARTHQUAKES IN WESTERN IRAN

The 12 November 2017 Ezgeleh earthquake, Mw=7.3, occurred at 18:18:24 GMT, in western of Iran (Figure 1).Seismic source parameters were determined by using teleseismic data and body-wave spectrum. Data was provided in the SAC format of the IRIS site, which includes 31 stations at a distance 30 to 90 degrees. P phase was selected on thevertical component and body-wave spectra were provided for each record. In this study, the seismic moment of Ezgeleh main shock was calculated using Keilis-Borok method (1960) and its mean value is 1.45E+27 dyne-cm. By using Brune (1971) method, source radius and stress drop of this event is calculated 12 km and 394 bar respectively. The 25 November 2018 Sarpol-e Zahab aftershock, Mw=6.3, occurred at 16:37:37.1 GMT, in southern part of the study area. Seismic energy calculated by using body-wave spectrogram (Thomas et al., 1972) and is equal to 3.7×1011 joule (Figure 2).

Keywords:

Seismic moment , Body-wave spectrum , Energy , Stress drop