With 30 aftershocks felt since the massive 7.8 temblor rocked Nepal around noon on Saturday, the `unsteady' Earth in the region continues to cause fear among people and poses a challenge to seismologists.

A couple of the aftershocks have touched a magnitude of 6, which most often results in damage and also can be felt in large areas. "We expect the activity to go on for a few weeks or even a month. Our scientists (geologists) will in the next few days assess the damage and understand the mechanism of the large earthquake," said N Purnachander Rao, Principal Seismologist at the CSIR - National Geophysical Research Institute (NGRI) here.

An aftershock in simple terms is the adjustment of the earthquake zone. The energy released by the big jolt gets settled over a period. The NGRI will also study the expression of the quake on the surface of the earth and collect data from the Indian side of the Himalayan region, where it has established an extensive network of seismic centres which have collected valuable data, Rao told BusinessLine today.

For seismologists, who have been expecting a big earthquake in the region, especially after the Tsunami triggered, 2004 Sumatra-Andaman earthquake measuring 9.1, the Saturday event offers experts a rare chance to thoroughly analyse and study the earthquake mechanism thanks to the technology advancements made so far.

The last big event in 1934 on the Nepal-Bihar border of a magnitude of 8 and the 1950 Arunachal Pradesh quake (8.5 magnitude) caught people and earth scientists off-guard with the latter ill-equipped to study nature's fury. There are few scientific recordings of the events.

The NGRI is planning to deploy GPS (Global Positioning Systems) instruments along the fault zones of the earthquake-hit region to understand the movement of the blocks post the event. The devices which have an accuracy of millimetres have proved useful in the study in the Andaman region after the 2004 earthquake. The NGRI gathered crucial data which helped in piecing together some of the movements and mechanisms of the earthquake, Purnachander Rao said.

The NGRI is a key national institute studying earthquakes and has established a modern globally networked Seismology Centre in Hyderabad. It has several field stations in the Indo-Gangetic plains and the Himalayan region where the collision of the tectonic Indo-Eurasian plates makes it an active seismic zone prone to big earthquakes.

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