“RESERVOIR INDUCED SEISMICITY DUE TO TEHRI DAM”

Abstract

Reservoir Induced Seismicity (RIS) refers to earthquakes that are triggered or induced as a result of artificial filling of reservoirs. As of today over 100 cases of reservoir induced seismicity have been registered throughout the world, the most damaging and severe case having been occurred due to Koyna Dam on December 10, 1967 where a 6.3 magnitude earthquake was triggered by the reservoir. Investigation of RIS is important from several viewpoints: to check for safer sites where a dam can be constructed and mitigation of any hazard due to triggered earthquakes, to improve our understanding of the physics of earthquakes. Events of highly damaging RIS have occurred in the past at Hsinfengkiang (China), Kariba (Zambia), Kremsata (Greece), Koyna (India), Oroville (California) and Aswan (Egypt). In this project deep understanding of the phenomenon of reservoir induced seismicity and the parameters affecting RIS have been studied. Calculation of reservoir induced seismicity using probabilistic approach for Tehri dam has been carried out. Tehri is a rock and earth dam constructed over River Bhagirathi in the Indian state of Uttarakhand. With a height of 260.5m and volume of over 3000 million m3 it is the highest dam in India. The dam is constructed for the purpose of irrigation and power generation. Previous research suggests that there lies an active fault beneath Tehri Dam at a distance of approximately 4.5 to 5km beneath the surface which makes this study a matter of concern and importance.