An investigation of seismicity for western Anatolia

Abstract

In order to investigate the seismicity of western Anatolia limited with the coordinates of 36 degrees-40 degrees N, 26 degrees-32 degrees E, Gutenberg-Richter magnitude-frequency relation, seismic risk and recurrence period have been computed. The data belonging to both the historical period before 1900 (I-0 >= 5.0 corresponding to M-S >= 4.4) and the instrumental period until the end of 2006 (M-S >= 4.0) has been used in the analysis. The study area has been divided into 13 sub-regions due to certain seismotectonic characteristics, plate tectonic models and geology of the region. All the computations have been performed for these sub-regions, separately. According to the results, a and b values in the computed magnitude-frequency relations are in the intervals 3.19 +/- 0.17 - 5.15 +/- 0.52 and 0.42 +/- 0.05 - 0.66 +/- 0.07, respectively. The highest b values have been determined for sub-regions 3 and 12 (Demirci-Gediz and Gokova Gulf-Mugla-Golhisar). The lowest b values have also been determined for sub-regions 1 and 9 (Balikesir and Bodrum-Istankoy). Finally, seismic risk and recurrence period computations from a and b values have shown as expected that sub-regions 1 and 9 which have the lowest b values and the highest risks and the shortest-recurrence periods.