Press Esc to close
Monday 23 January 2017
News updated at 6:09 PM IST
Weather
Max: 30.3°C
Min : 16.8°C
In Bengaluru
Sunny day
Breaking News

Tehri dam sitting on an active fault: seismologists

Hyderabad, Dec 9, 2012 (IANS)
There is an active fault beneath the Tehri dam that enhances the earthquake risk, scientists of the National Geophysical Research Institute (NGRI) here have reported. The Tehri dam is located near Tehri town in Uttarakhand in the Kumaon-Garhwal Himalayas region.

"The tectonic loading on this active fault due to local seismicity, coupled with the reservoir loading and unloading, may generate earthquake(s) and cause additional seismic risk in this critically stressed region," Sandeep Gupta and co-workers in NGRI claim in their report in the latest issue of "Current Science" published by the Indian Academy of Sciences.

They say their conclusion is based on evidence obtained by mapping of the seismicity pattern in the Kumaon-Garhwal Himalayas region in general and around the Tehri dam in particular, using observations from a temporary seismological network they operated for over 39 months during 2005-2008. During this period, over 20 earthquakes of magnitude 1.6-2.8 on the Richter scale were recorded in a 20-km radius of the dam site.

According to the scientists, the dam site was chosen in 1961, "at the time when the plate tectonics theory was taking birth and researchers were not well-educated with the fundamental mechanism responsible for earthquakes in the Himalayas. Since then, much has changed in the context of our theoretical understanding and observations related to the evolution of the Himalaya and the associated earthquake hazards".

The Tehri dam falls in a region of possible future great earthquakes, the researchers say. The last major earthquake of magnitude 7.7 occurred 209 years ago, in 1803, close to Srinagar-Garhwal. Many intermittent earthquakes including the 1991 Uttarkashi earthquake (magnitude 6.8) have rocked the region and released parts of energy stored elastically due to the movement of the Indian plate.

"Still, a large amount of residual stress has to be released by an earthquake of magnitude possibly not less than 8," the NGRI scientists claim. They say that geodetic levelling observations in the region also suggest the possibility of great earthquakes to release the recoverable elastic strain stored in the upper crust of the outer Himalayas in this part of the Himalayas.

According to the NGRI team, the Tehri dam was initially designed to withstand ground acceleration expected from the maximum credible earthquake of magnitude 7.2, whereas the ground acceleration would be twice this if an earthquake like the 1905 Kangra temblor strikes again.

The scientists have also studied the seismicity around the dam in relation to reservoir filing. They observed an increase in seismicity from December 2005 onwards, after its first filling in October 2005. "We, thus, speculate that seismicity in the vicinity of the Tehri dam may have a linkage with instability created by loading and unloading of the reservoir."

This, coupled with the close proximity of the seismically active fault to the dam, has serious implications for the earthquake hazard scenario and calls for "re-assessment, analysis and further examination of our results using dedicated ground and space-based seismic and geodetic networks," the scientists concluded.

 

Go to Top

Photo Gallery
Olympic finalist Gymnast Dipa Karmakar being felicitated with Assames japi,Khoria and gomacha...

Olympic finalist Gymnast Dipa Karmakar being felicitated with Assames japi,Khoria and gomacha...

A boat man carries Hindu devotees in the river Yamuna early in the morning during magh Mela in...

A boat man carries Hindu devotees in the river Yamuna early in the morning during magh Mela in...

Austria's Michael Matt speeds down the course during an alpine ski, men's World Cup slalom...

Austria's Michael Matt speeds down the course during an alpine ski, men's World Cup slalom...

Punjab tableaux artists pose a photo during a press preview in New Delhi on Sunday...

Punjab tableaux artists pose a photo during a press preview in New Delhi on Sunday...

AIADMK leader SP Velumani inaugurates Cattle race after the urgent law was passed for...

AIADMK leader SP Velumani inaugurates Cattle race after the urgent law was passed for...

Bollywood actors Madhuri Dixit and Manish Paul atteded the ‘Umang Mumbai Police Show 2017’ in...

Bollywood actors Madhuri Dixit and Manish Paul atteded the ‘Umang Mumbai Police Show 2017’ in...

Youngstres and Students during the protest to Lift ban on jallikattu and impose ban on PETA...

Youngstres and Students during the protest to Lift ban on jallikattu and impose ban on PETA...

India Captain Virat Kohli celebrate after his 50 runs during 3rd ODI against England at Eden...

India Captain Virat Kohli celebrate after his 50 runs during 3rd ODI against England at Eden...

Rescue and relief work in progress at the site where Jagdalpur-Bhubaneswar Express train derailed...

Rescue and relief work in progress at the site where Jagdalpur-Bhubaneswar Express train derailed...

Samajwadi Party Vice president Kiranmoy Nanda, SP state president Naresh Utam and Congress state...

Samajwadi Party Vice president Kiranmoy Nanda, SP state president Naresh Utam and Congress state...

Like us on Facebook

Copyright 2014, The Printers (Mysore) Private Ltd., 75, M.G Road, Post Box 5331, Bengaluru - 560001
Tel: +91 (80) 25880000 Fax No. +91 (80) 25880523