A series of six tremors of moderate to severe intensity within a month in the Northeast has led seismological experts to warn of a higher magnitude earthquake in the region.
Noted scientist Prof S K Sarmah, who has conducted intensive research on the seismological trends in the Northeast, said studies on earthquake patterns indicated that strain had been building up in some parts of the region. He said there was probability of an earthquake of agreater magnitude.
The region was jolted by six earthquakes of varying intensities during August-September. The first occurred on August 11, with a magnitude of 4.8 on the Richter Scale followed by another the next day with intensity of 5.6 on August 19, another quake struck with the magnitude of 4.9 on the Richter Scale followed by another on August 31, with an intensity of 5.3.
On September 21, a 6.3 intensity quake struck the region followed by another early the next day recording 5.7 on the Richter Scale. "There is anomalous variation of compressional wave velocity ratio with time in the region and the number of small magnitude earthquakes are increasing while larger magnitudes are decreasing," Sarmah explained.
These facts, together with computed return periods for high magnitude earthquakes of the region and historical seismicity, tend to indicate the probability of occurrence of a high magnitude earthquake in the Northeast at any time within the next few years, Sarmah said. Experts, however, are unanimous that exact prediction of seismic events remain elusive.
"Earthquakes cannot be predicted by anyone, anywhere, in any country. This is a scientific truth. Seismologists are, however, in a position to indicate the possibility of quakes in potentially large areas based on palaeoseismicity, micro seismic activities and precursors," said geologist D K Barman.
Northeast India is seismically one of the six most active regions of the world, the other five being Mexico, Taiwan, California, Japan and Turkey. It is placed in Zone five, the highest zone of the seismic zone map of India. It lies at the junction of the Himalayan arc to the north and Burmese arc to the east.
The high seismicity in the region is attributed to the collision between the Indian tectonic plate and the Eurasian tectonic plate in the north and subduction tectonics along the Indo-Myanmar range in the east.
