GUWAHATI, April 29 - Of the earthquake vulnerable areas of the NE region, the Arakan-Yuma area has accumulated enough strain energy till date, which may lead to a major earthquake. This is the observation of Prof Sarbeswar Kalita, head of the Department of Environmental Science, Gauhati University (GU).
Prof Kalita, who is known for his study of seismic event-related developments, was talking to this correspondent.
It needs mention here that the Arakan-Yuma region was the epicentre of the great 8.6 magnitude earthquake that shook the NE region on August 15, 1950 in a devastating manner. Prof Kalita pointed out that there is also strain energy accumulation in the Shillong Plateau and such accumulation was also observed in the Indo-Myanmar border area. But the strain energy of the latter has now been released by two significant earthquakes in January and April this year.
In the case of the Shillong Plateau, the centre stage of the historic 8.3 magnitude earthquake of 1897, R Bilham of the University of Colorado, USA, and VK Gaur, a former scientist of the Indian Institute of Astrophysics, Bangalore, are of the opinion that recurrence of an earthquake of the magnitude of the 1897 one would require around 400 years in that area. Both the scholars attribute this to the peculiar geological condition prevailing in the Shillong Plateau area, said Prof Kalita.
Both Bilham and Gaur are of the opinion that the June 12, 1897 earthquake occurred due to the popping up of the Shillong Plateau under the impact of the tectonic blocks around it. They maintain that such developments require hundreds of years to recur, said Prof Kalita. He, however, added that there is another vulnerable area in the NE region in this respect. This is the Kopili lineament area in middle Assam. The worrisome thing concerning this area is that an earthquake here would be of shallow or medium focus and such earthquakes have the potential of causing more damage, compared to the ones with deep focus. Significantly, this lineament is located between Nagaon and Guwahati, said Prof Kalita.
On the duration of the earthquake jolts, he said that the duration of an earthquake depends on its magnitude. The jolt of an earthquake lasts longer if it is of a greater magnitude. Then again, aftershocks – the jolts that follow the main jolt – occur because of the adjustment efforts of the tectonic blocks after the earthquake, he said.
He maintained that some significant incidents of release of the accumulated strain energy have taken place in the western part of the Eastern Himalayas, covering Nepal, Sikkim and Bhutan. But the eastern part of this tectonic belt seems to be comparatively dormant after the great August 15, 1950 earthquake.