Temporal and Spatial Variations of b-value in the Western Anatolia

The b-value calculated in time and the spatial variations for different regions of the Western Anatolian (WA). The whole examined area is divided into 15 seismic regions based on their seismotectonic regime. The data used in this work was taken from different sources and catalogues such as TURKNET, International Seismological Centre (ISC), Incorporated Research Institutions for Seismology (IRIS) and The Scientific and Technological Research Council of Turkey (TUBITAK) for instrumental periods. The technique of maximum likelihood method is applied. Temporal variations of b-value can be used to prediction of major earthquakes. Spatial distributions of b-value point out which fault system how has stress level. In order to determine the evolution in time of b-value, we used a moving-window technique. To evaluate spatial distribution of b-value, we used 0.50 grid interval. We plotted b-value in time and identified b-value decreases before the major earthquakes in 15 seismic regions. We have found which fault system has higher stress level from spatial distributions of b-value. The values smaller than 0.70 are related to the Aegean Arc and Eskisehir Fault. The highest values are related to Sultandağı, Aliağa and Sandıklı Faults. The observed values in the graben sytems are approximately equal to 0.90.