A large earthquake of magnitude 8 or more on the Richter scale could take place in the Kumaon-Garhwal region of the Himalayas in future, seismic imaging and modelling studies conducted by CSIR-National Geophysical Research Institute (NGRI) and Stanford University have indicated.
According to Shyam Rai, Chief Scientist heading the seismic tomography group at NGRI, a network of 50 seismographs was deployed in the Kumaon-Garhwal region which helped delineate precisely where the earthquakes could occur in Uttarakhand.
Dr.Rai said that the team found the under-thrusting angle to be close to 16 degrees which is much higher than what was projected earlier.
Observing that earthquakes of this magnitude have a cycle of 180-190 years, he pointed out that the last big tremor to hit that area was in 1803. “The possibility of having a major earthquake is high as the strain accumulation is very large,” he said.
It was not possible to predict when the earthquake would occur, however. The impact of the earthquake could be felt up to Delhi if it was shallow, he added.
Dr. Rai wanted a proper land management programme to be implemented besides constructing earthquake-resistant buildings. There was also a need to have a permanent network of about 50 seismic and geodetic stations in the Himalayas to help in identifying areas vulnerable to earthquakes. GPS data would enable in finding strain accumulation and the deformation that was taking place.
In the context of the floods in Uttarakhand, he said “the processes happening inside the earth in the Himalayan region have contributed significantly to the climate pattern in India. The Himalayas are rising but are kept at constant level because of the erosion of the mountains on top. The tectonics, erosion and climate are interlinked.”
The seismic imaging had shown that there was a sudden change in the nature of the Indian crust at the higher Himalayan region.
The study initially carried out independently by NGRI between 2005 and 2008 was later done in collaboration with researchers from Stanford University. The findings were presented at the meeting of American Geophysical Union in December last.