Are frequent tremors in Gujarat's Saurashtra region a precursor to an earthquake similar to the killer one that devastated the state in 2001?This is the question the Gandhinagar-based Institute of Seismological Research (ISR) has been researching for the past two years.Set up under the department of science and technology after the 2001 earthquake in Kutch, ISR has been conducting round-the-clock study on seismic activity in the state since 2005. The tremors in Saurashtra have once again come into focus after two consecutive ones that hit the region yesterday."We have been conducting a detailed study of the tremors and the subterranean booming sounds, which have been emanating from different parts of the Saurashtra peninsula," ISR Director General B K Rastogi said."In 2006 alone, there were more than 200 such shocks of which 50 of them had a magnitude of 1.5 or more on the Richter Scale," he said."These shocks were largely confined to the Kalavad taluka of Jamnagar district.""However, this year, the area from where the shocks emanated have grown and spread in an area measuring about 20 km," he said, while explaining how the frequency of seismic activity in Saurashtra has increased and spread to a larger geographical area."This year alone, we have already felt 200 such mild shocks and tremors," Rastogi said, adding "most of the seismic activity has been concentrated around Lalpur (in Jamnagar district), about 30 km southeast of Jamnagar city. In the event of such development, a large, damaging earthquake cannot be ruled out in Saurashtra region."He said similar activity was also witnessed before the devastating earthquake, which struck Latur in Maharashtra in 1993.Describing the seismic activity pattern in Saurashtra as "swarm-type", Rastogi said: "These shocks have occurred in a swarm, very near to each other at different intervals of time."According to him, Saurashtra region is surrounded by three of the eight major geological faults that exist in Gujarat, making it more susceptible to a major earthquake."Earthquakes are caused mostly by rupture of these faults. They also sometime happen along hidden faults," he remarked.Rastogi said ISR has set up a network of 22 permanent seismological observatories with state-of-the-art digital broadband seismographs in different parts of Gujarat.ISR, which records round-the-clock data of seismic activity in Gujarat, has also set up another network of 40 strong motion accelerographs to record strong motions occurring on the ground."Though the exact date of an earthquake cannot be predicted, by studying the seismic data, some sort of a model for forewarning can be developed."Rastogi said seismic data can also be used to design and construct quake-resistant buildings.(Reporting by Avinash Nair)
