Statistical Evaluation of Induced Seismicity at the Karkheh Dam, Iran

Abstract

Karkheh Dam is the largest dam in Iran with a capacity of about 7.4×109 cubic meters and height of 127 meters. Since the first impoundment, increasing in seismic activity in the dam area has been observed that indicates the possible occurrence of reservoir-induced seismicity (RIS).In the present work, a preliminary evaluation is conducted firstly in order to investigate these observations. Based on the assessment of the number of earthquakes occurred in equal time periods before and after reservoir impoundment and their focal depths, it is concluded that RIS is happening in the dam site. Secondly, a cross-correlation method is applied in order to find the relationship between water level fluctuations and the variations of seismic activities. This analysis confirms a strong relationship between fluctuation of the water level and the number of seismicity events in the dam area.