Koyna earthquake of December 11, 1967: Report of the Expert Committee on electrical and mechanical equipment

Hydroelectric power generators are common in seismic regions throughout the world and their ability to withstand earthquakes is important to public welfare. There is very little information in the literature about the effects of earthquakes on such installations; hence, the report of the Expert Committee should be of special interest to all who are responsible for designing and operating hydroelectric plants. The report describes what happened at the power station during and after the earthquake and makes recommendations for improving the earthquake resistance. The magnitude 6.5 earthquake, thought to have been triggered by the reservoir loading, centered about 3 km south of the dam. A strong-motion aecelerometer installed within the 338-ft high, concrete gravity dam recorded a peak acceleration of about 50 per cent g, with the frequencies in the motion being appreciably higher than those shown by U. S. earthquakes. The 540-MW electric-generating station was located about 8 km WNW of the dam. The effect of the earthquake on the dam has been described in a paper by G. V. Berg et al., The Koyna, India Earthquakes, Proceedings of the Fifth World Conference on Earthquake Engineering, Santiago, Chile, 1969, and also in UNESCO Report of the Committee of Experts on Koyna Earthquake of December 11, 1967, New Delhi, 1968. The effect of the earthquake on the power generating station is summarized in the following description which has been abstracted from the report.