Reservoir-induced seismicity in Karun III dam (southwestern Iran)

摘要

Statistical analyses of the Karun III reservoir seismicity reveal a remarkable correlation between seismicity rate and water-level harmonic changes. It seems that seismicity in this dam depends on rapid water-level changes. The three biggest earthquakes of Karun III, measuring 4, 4.1, and 4.3 on the Richter scale (ML), occurred after two stages of rapid filling of the dam on March 22, 2005 and May 12, 2006. These earthquakes happened when the water reached the maximum operational level. Since the beginning of filling the reservoir on November 8, 2004 until March, 2006, most reservoir-induced seismicity has been localized in three main clusters. The majority of the earthquakes occurred in the frontal anticline of Keyf Malek; the second and third clusters happened near Karun Blind Fault (KBF) and Mountain Front Fault (MFF), respectively. Filling Karun III reservoir immediately led to an increase in the occurrence of earthquakes. Further, following abrupt water-level changes, a considerable increase in the number of earthquakes is observed. Finally, in terms of seismicity rate, vertical and horizontal migration, magnitude, and distance, the earthquakes of Karun III behave differently.