Description

The fact that filling of an artificial water reservoir could alter the earthquake occurrence in the vicinity of a reservoir was scientifically established way back in 1939 when enhanced earthquake occurrence in the vicinity of Lake Mead, Colorado, USA was related with the filling of the Hoover Dam. Over the years artificial water reservoir triggered earthquakes have been reported from all over the world. At least at 5 sites earthquakes exceeding magnitude 6 have occurred, causing loss of human lives and substantial damage to properties and infrastructure. Globally, certain anthropogenic activities lead to inducing/triggering of earthquakes. Among these, the reservoir triggered seismicity (RTS) is most prominent. At several locations, construction of artificial water reservoirs, enhanced oil recovery through fluid injection, geothermal power production etc. had to be given up due to realization of the possibility of triggering/inducing earthquakes. The book provides an overview of all RTS sites and earthquake occurrence. RTS is found to have characteristics different from the normal earthquake sequences occurring in the nearby region of RTS sites. The book deals with the RTS mechanism, how to find safer sites for construction of artificial water reservoir and related issues. Among all the RTS sites, Koyna, India is most prominent where the largest RTS event of magnitude 6.3 occurred in 1967 and RTS has continued till now. A detailed description of the studies conducted at Koyna, India including setting up a bore-hole observatory for near-field study of earthquakes is provided. It is shown that the important question as to how earthquakes nucleate could be found from studies at Koyna, India and RTS sites elsewhere in the world. The book also provides an overview of the injection induced earthquakes occurring in Oklahoma, USA.