THE SPATIAL ANALYSIS OF b-VALUES OF THE AREA BETWEEN BODRUM AND FETHIYE DISTRICTS, THE SOUTH-WESTERN ANATOLIA, TURKEY

Abstract

The estimation of the variation of the b-value, which is frequency distribution of a magnitude given in an earthquake data set of any region, is important parameter for interpretation of tectonic mechanism and seismic hazard assessment of that region. There is an inverse correlation between stress and b-value. The magnitudefrequency relationship is described by the well-known the Gutenberg-Richter relationship. The purpose of this paper is to investigate the recent seismicity of the region between the Bodrum and Fethiye, the south-western Anatolia in Turkey. A total of 27357 earthquake data is taken into account in this study in the period between 2004 to 2020 with magnitude (Ml) larger than 2. The majority of focal depths of earthquakes are concentrated between 0 and 33 km. The b-value in the Gutenberg-Richter relationship was estimated by the maximum likelihood method in this study. The estimated b-values range between 0.5 and 2 in the study region. While the lower b-values (0.5-1) are located at the SE of the study area (mainly the Beydağları unit), higher values (1-2) are trending on the west-east direction along the fault zones. The highest b-values in the study area are possibly related with the brittle lower-mid crust, thermal regime, normal faults and young basins bounded by these faults.