بررسي پيش لرزه ها به منظور مطالعه لرزه خيزي در منطقه دورود-بروجرد

Application of the Foreshocks for Seismicity Studies in the Doroud Borujerd Region

In this paper, the foreshocks in the Doroud-Borujerd region have been studied. In this regard the IIEES catalog has been used in two periods, 1960-2004 and 2004-2006. After applying magnitude threshold and removing the dependent events, such as aftershocks, from each event, the remained mainshocks are considered to find their foreshocks in a time- space window. In the period 2004-2006, 3 mainshocks out of 6 with magnitude greater than 4 are preceded by foreshocks. These foreshocks had happened in a distance of 10-13 km from their related mainshock and between 1-5 days before it. However, in the period 1960- 2004 only one earthquake was preceded by foreshocks. It should be mentioned that the latest result may be unreliable due to insufficient number of stations and not recording all events.