Investigation of the reduction pattern of aftershocks in the Iranian plateau

Abstract

The Iranian plateau is one of the most active and seismic areas, which is located in the Alpine-Himalayan seismic belt. This area has experienced many devastating earthquakes. The study of seismic behavior and the occurrence pattern of aftershocks of medium to large earthquakes can be important for this region. Twenty six earthquakes larger than 5 have been selected on the Iranian plateau in the last ten years to investigate their aftershocks behaviour. First the seismic parameters Mc, a and b-value were estimated by drawing the Gutenberg-Richter diagram using the maximum likelihood estimation method in ZMAP software. Then, events less than Mc were removed from the catalog. The remaining catalog was used to determine the parameters of modified Omori law for each event separately. The average value of p in Zagros and Alborz is 1.07, while this value is 0.99 for Central Iran and Kope Dagh. This can be caused by high seismic activity and rapid energy discharge by small earthquakes. Furthermore, in this study, a model for the distribution of the probability function of the waiting time of aftershock sequences of the Iranian plateau has been determined.