Koyna Dam

The Koyna Dam is a large dam in western India. It is located in Koyna Nagar in the state of Maharashtra, 200 km south whose capital Mumbai. The reservoir is called Shivaji Sagar.

Dam

As a shut-off, it has a gravity dam made ​​of concrete. It was 1962/63 and 1963 built dammed for the first time. Is dammed the river Koyna, a tributary of the Krishna. The dam is used to generate hydroelectric power.

Earthquake

The earthquake of 1967

The dam was at 22:51 UTC shaken on 10 December 1967 ( on December 11 at 4:21 clock time) of an earthquake, which was most likely induced by the dam itself ( Kaiser effect, induced seismicity ). This means that the earthquake was caused by the load of the reservoir. It is with its magnitude between 6.5 and 7.5 on the Richter scale and accelerations of 0.65 g as the strongest dams -induced tremor at all.

At the time of the earthquake, the reservoir was not filled. The water level was 91.75 m above bottom, 11.25 m were to the wall crown free.

The earthquake caused major damage to the dam, but did not rupture, although the dam was not rated for such a large accelerations, but only for 0.05 g at a height of 66.5 m, the dam has on the air side of a kink in the contour. At this buckling, cracks. These were at an altitude 60-66 m through to the water side.

It also emerged some leaks. Water leaked from these. A crane overturned, a tidal wave, however, there was not. The earthquake, however, between 177-200 people were killed. The reasons for this but not the dam itself, the dam was later extensively studied, repaired and reinforced.

More quakes

Since 1967, 17 earthquakes M ≥ 5, more than 150 earthquakes M ≥ 4 and several thousand smaller events were measured.

Under the dam and the dam is a Holocene fault should be located. It is believed that the quake series will continue for 3-4 decades until the gespeichterten voltage loads have been mined in smaller quakes.