Fractal dimension and earthquake frequency-magnitude distribution in the North of Central-East Iran Blocks (NCEIB)

The Gutenberg–Richter parameters (a and b), fractal dimension (DC), and relationships between these parameters are calculated for different regions of the North of Central-East Iran Blocks (NCEIB). The whole examined area (between 34°-36° N and 55°-61° E) is divided into 55 equal square grids. Both the a and b values for the frequency-magnitude distribution (FMD) and the fractal dimension (DC) are investigated simultaneously from 55 equal square grids. By using the completeness earthquake dataset for earthquakes of the instrumental period from 1976 to 2015, it is concluded that calculated values of a, b and DC imply variations of seismotectonic stress.The most vulnerable regions for occurrence of the large earthquakes in the NCEIB considering the computed lowest b-values and the highest DC -values. The relationships among DC -b and DC - (a/b) are used to classify the level of earthquake hazards for individual seismic source zones, in which the calibration curves illustrate a positive correlation among the DC and b values and also a positivecorrelation among the DC and a/b ratios having similar regression coefficients (R2 = 0.80 to 0.87) for both regressions. It is observed that the relationship among a/b and DC may be used for evaluation of seismicity and earthquake hazard assessment because of the high value for correlation coefficients and limited scattering of the calculated parameters