An empirical method to estimate fatalities caused by earthquakes: the case of the Ahar-Varzaghan earthquakes (Iran)

The dual Ahar-Varzaghan earthquakes occurred on August 11, 2012, at 16:53 (Iran standard time) in East Azerbaijan province of Iran. The two quakes measured 6.3 and 6.4 on the moment magnitude scale, with the second quake occurring 11 min after the first. Local reports estimated at least 306 deaths, although official reports stated 229, with more than 3000 injured. Most casualties occurred in rural and mountainous areas. The fatalities from the Ahar-Varzaghan earthquakes have been analyzed and a model proposed for estimation of fatalities. The model correlates the fatality count and intensity measures or distance parameters. The peak ground acceleration (PGA) in the village was selected as the intensity measure; thus, the recorded or predicted PGA in the locations suffering fatalities was required. Available ground motion prediction equations (GMPEs) were first used. Because the GMPEs did not fit the recorded data, a simple GMPE was developed using the equation best fitted to the recorded data. The correlations between the number of fatalities and the PGA or distance from epicenter to village were assessed by gender. The results show that the number of fatalities has a stronger relationship with PGA than distance.