Regional variations and correlations of Gutenberg–Richter parameters and fractal dimension for the different seismogenic zones in Western Anatolia

We investigated the regional variations of Gutenberg–Richter (G–R) parameters (a and b) and fractal (correlation) dimension (DC) and relations among these parameters for the different regions in Western Anatolia (WA). The whole examined area (26–33°E, 33–40.5°N) is divided into 15 different seismogenic regions based on their tectonic and seismotectonic regimes. We used database including 69,182 earthquakes for the instrumental period from 1900 to 2011. We calculated b value, which is the slope of the frequency–magnitude Gutenberg–Richter relationship, from maximum likelihood method (ML) and DC value, which is the slope of log10C(r) versus log10r, from correlation integral using the least-squares (LS) method. Computed values for 15 different seismogenic regions are mapped using different color scale for different range of values of b and DC. Regional distributions of these parameters reveal information about regional variation of stress level and geological complexity. We concluded Aegean arc and Aegean islands, Aliağa fault and Büyük Menderes Graben the most vulnerable regions for occurrence of the large earthquakes in WA considering the computed lowest b-values and the highest DC-values in these regions. Since DC/b values are the highest in these regions, this ratio may be used as an indicator of earthquake hazard levels of different seismogenic zones in a studied region. An effort is made to find relationships between the G–R parameters and fractal dimension. We observed negative correlation between DC and b values and positive correlation between DC and a/b values for different regions of WA. We observed that the relationship between a/b and DC can be used for seismicity, earthquake risk and hazard studies because of the computed high correlation coefficient and fewer scattering of these parameters.

► We investigated the regional variations of parameters of a, b and DC.
► We computed the lowest b-values and the highest DC-values in Aegean arc.
► We observed negative correlation DC and b values.
► We find positive correlation between DC and a/b values.
► We concluded the relationship between a/b and DC can be used for earthquake hazard studies.