Determination of Spectral Source Parameters from Broadband Earthquake Records in Western Anatolia (Türkiye)

DOI

https://www.doi.org/10.59256/ijsreat.20260601008

Published In

Volume 6, Issue 1 (2026)

Published Online

January-February 2026

Pages

55-64

Article Type

Original Article

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Spectral earthquake source parameters such as seismic moment, corner frequency, stress drop, and source radius are important parameters for describing the source characteristics of an earthquake. In this study, source parameters (3.2 ≤ M ≤ 6.7) for 370 local earthquakes that occurred in Western Anatolia were calculated. The database of broadband earthquake stations from earthquakes that occurred between 2002 and 2019 in the Marmara Region, the Aegean Extension Region, and the Fethiye Fault Zone was created from the seismic station network of Boğaziçi University Kandilli Observatory Regional Earthquake and Tsunami Research Center (KOERI-RETMC). Displacement and acceleration spectra of SH waves were analyzed using the Brune source model. A total of 10,413 waveforms were examined for 370 earthquakes, and the parameters for each earthquake were calculated manually. The seismic moment values obtained from the earthquakes ranged between 8.37×10¹³ and 1.64×10¹⁹ Nm, while the corner frequency values ranged between 0.13 Hz and 9.34 Hz. Furthermore, the radii of the circular rupture zones varied between 0.11 km and 11.75 km, and the stress drops in these zones ranged between 0.002 MPa and 29.5 MPa. According to the results obtained, the relationships of these three spectral parameters with Seismic Moment were calculated as follows: for the Marmara region, Mo=1016fc-1.93, log(Mo)=1.67log(r)+10.67 and log(Mo)=0.66 log(sd)+15.81; for the Fethiye and surrounding areas, Mo=1.34.1016fc- 2.88, log(Mo)=2.63.log(r)+7.61 and log(Mo)=1.3.log(sd)+16.47; and for the Aegean region, Mo=2.12.1016fc-2.42, log(Mo)=2.79.log(r)+7.04 and log(Mo)=0.93.log(sd)+16.85. In conclusion, these empirical relationship functions, calculated for three different regions at the local level and of great importance in terms of representing the relevant regions and providing input for further seismological studies, have been interpreted comparatively with the results obtained in tectonically active regions.