Spatial variations of seismotectonic b and Dc-values in and around the East Anatolian Fault Zone (EAFZ), Turkey

Abstract

An evaluation of recent seismicity behaviors in the East Anatolian Fault Zone, eastern part of Turkey, is made by using Gutenberg-Richter b-value and fractal dimension Dc-value. Reasenberg's algorithm is used in order to separate the dependent events from independent ones. The completeness magnitude in study region is calculated as 2.8. b-value is calculated as 1.02+/-0.01 by maximum likelihood estimation and matches the Gutenberg-Richter law with a b-value typically close to 1. Dc-value is found as 2.34+/-0.04 with 95% confidence limit by linear regression and this large value suggest that seismicity is more clustered at larger scales in the East Anatolian Fault Zone. The smallest b-values and the highest Dc-values are found in the same areas covering the East Anatolian Fault Zone, Aşkale Fault, Sancak-Uzunpinar Fault Zone, Pülümür Fault, Göynük Fault Zone and Genç Fault, in and around Karataş-Osmaniye Fault Zone and in the southeast part of the study region. Thus, low b-value in these regions may be an indication of low degree of heterogeneity, high-strain due to the active tectonics and stress to build up over time and to be released by events. Thus, special attention should be given to these regions where low b-value and large Dc-value are observed.