This is the third tremor to have jolted the region so far this month - an earthquake measuring 4.9 on the Richter scale took place Aug 19, while another measuring 5.6 shook the region Aug 11.

'Our study shows that a big earthquake is due in this region within a short time,' said Surjya Kanta Sarmah, a professor of geophysics at the Guwahati University in Assam.

The seven northeastern states -- Assam, Meghalaya, Mizoram, Tripura, Nagaland, Arunachal Pradesh and Manipur, considered by seismologists as the sixth major earthquake prone belt in the world, experienced India's worst earthquake, measuring 8.7 on the Richter scale, in 1897, killing 1,600 people.