Artificial water reservoirs and earthquakes: A world-wide status

Huge artificial water reservoirs are created all over the world for generation of hydroelectric power, flood control and irrigation purposes. Carder (1945) , for the first time pointed out that there is an association of earthquakes with reservoir loading at Lake Mead in the United States. By now, some eighty examples of reservoir-induced changes in seismicity are known. Earthquakes of magnitude 6 or more have occurred at Hsinfengkiang, China (1962); Kariba, Zambia/Zimbabwe border (1963); Kremasta, Greece (1966) and Koyna, India (1967). Recent important examples are those of Lake Aswan in Egypt, and Bhatsa in India. The work carried out by us led to the generation of criteria to differentiate natural earthquakes from induced earthquakes. These criteria are now internationally applied. A question which is very often asked is why Himalayan reservoirs do not trigger earthquakes. Non-occurrence of induced earthquakes in the foothills of the Himalaya is primarily due to thrust fault environment which is not conducive for reservoir-induced seismicity. However, these dams are located in areas of high seismicity where earthquakes of magnitude 7 and more have occurred in the past.