Koyna Dam

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Shivaji Sagar Lake
The reservoir
The reservoir
Location: Maharashtra , India
Tributaries: Koyna
Major cities nearby: Koyna Nagar
Shivaji Sagar Lake (India)
Shivaji Sagar Lake
Coordinates 17 ° 24 ′ 6 "  N , 73 ° 45 ′ 8"  E Coordinates: 17 ° 24 ′ 6 "  N , 73 ° 45 ′ 8"  E
Data on the structure
Construction time: 1962-1963
Height of the barrier structure : 103 m
Building volume: 1,555,000 m³
Crown length: 807 m (other information: 850 m)
Slope slope on the water side : 24: 1
Data on the reservoir
Reservoir length 60 kmdep1
Storage space 2,797,400,000 m³
Koyna-Dam.jpg
The water side of the dam
Koyna-Dam2.jpg
The air side of the dam

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

Dam wall

As a barrier structure, it has a concrete gravity dam . It was built in 1962/63 and stowed for the first time in 1963. The Koyna River , a tributary of Krishna , is dammed . The dam is used to generate hydropower .

earthquake

The 1967 earthquake

The dam was shaken on December 10, 1967 at 22:51 UTC (December 11 at 4:21 a.m. local time) by an earthquake that 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. With its magnitude between 6.5 and 7.5 on the Richter scale and accelerations of 0.65  g, it is considered to be one of the world's strongest dam-induced earthquakes.

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

The earthquake caused great damage to the dam , but did not break it, although the dam was not designed for such high accelerations , but only for 0.05 g. At a height of 66.5 m, the dam wall has a kink in the contour on the air side . Cracks appeared at this kink. These went through at a height of between 60 and 66 m to the water side .

There were also some leaks. Water seeped from these. A crane fell over, but there was no tidal wave . However, between 177 and 200 people were killed by the earthquake. The reason for this was not the dam itself. The dam was later extensively examined, repaired and reinforced.

More tremors

Since 1967 17 earthquakes M ≥ 5, over 150 earthquakes M ≥ 4 and several thousand smaller events have been measured.

A Holocene fault is said to be located under the dam and the reservoir . It is assumed that the series of earthquakes will continue for another 3–4 decades until the stored stress loads are reduced in smaller earthquakes.

See also

literature

  • GW Housner: Seismic Events At Koyna Dam. The 11th US Symposium on Rock Mechanics (USRMS), June 16-19, 1969, Berkeley, CA . Ed .: American Rock Mechanics Association. American Institute of Mining, Metallurgical, and Petroleum Engineers Inc., 1969 (English, onepetro.org - abstract and print on demand, onepetro.org).
  • Harsh K. Gupta, Prantik Mandal, BK Rastogi: How Long Will Triggered Earthquakes at Koyna, India Continue? In: National Geophysical Research Institute (Ed.): Current Science . tape 82 , no. 2 . Hyderabad January 25, 2002, p. 202–210 (English, iisc.ernet.in [PDF; accessed on April 15, 2014] with an extensive inventory of seismic events).

Web links

About the earthquake:

Individual evidence

  1. ^ Lit .: Gupta, Mandal, Rastogi: How long ..., abstract, p. 202 (PDF, p. 1).