Variation in seismicity in the Zagros Fold-Thrust Belt(Between kazerun and Sarvestan Faults)

The Zagros fold-thrust belt is one of the most seismicity active zones of the Iranian plateau and Its seismic behavior has certain complexities and changes in space and time under influence of various factors. Based on various studies on seismic data recorded in the area between Kazerun and Sarvestan faults, Some complexities in the seismicity changes of this part of the Zagros fold and thrust belt have been investigated. The main faults in the region are Zagros Mountain front faults, Zagros foredeep fault, Kazerun-Borazjan, Sabzpooshan, Qir and Sarvestan Faults. By preparing scattering maps and depth changes of seismic data, it was determined that earthquakes are mainly concentrated around the main faults in terms of number and magnitude and occurred at depth of less than 20 km.. Estimation of seismic parameter by using Gutenberg-Richter model shows the β value is 1.55± 0.03 and λ for Mmin equal 2.8 is 12.07±0.6 . Spatial changes of seismicity have been investigated using networking and plotting changes of a-value and b-value parameters. Changes in a range from 3.98 to7.64.The changes of b in the region are from 0.44 to 2.4. The highest value of a and b occurred in the western and southeastern part of the region Which indicates the existence of smaller earthquakes that occurred in these parts and more of them. Analysis of seismic data shows that one of the seismic factors of the region is transverse faults that are mainly basement faults and control the shape of the folds in the area.