Is India prepared to tackle earthquakes?

Bangalore: Despite the chorus of assurances from Prime Minister Manmohan Singh downward that Indian nuclear plants are safe because they are away from geological faults that can generate earthquakes or tsunamis, some of India's leading geologists voiced concern in the wake of the devastation caused by the 9-magnitude quake in Japan.

K.S. Valdiya, a renowned geologist at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bangalore, is one of those who believe that complacence will be harmful.

It is true the Dec 26, 2004, Indian Ocean tsunami did not result in any damage to the Madras Atomic Power Station at Kalpakkam except causing some flooding, but Valdiya says this was because the tsunami originated from the subduction zone near Sumatra some 1,400 km away from India.

"The same subduction zone (where two oceanic plates come together, one riding over the other), as deep as near Sumatra, continues north towards the Andaman Islands," Valdiya pointed out.

According to him, had the tsunami originated from near the Andaman Islands, instead of Sumatra, the waves would have lashed India's eastern coast with much greater ferocity and travelled much farther inland.

Many tsunami-generating earthquakes had taken place near the Andaman Islands and there is no guarantee that in future such mega-events will not take place there closer to the eastern shore of mainland India, he maintained.

Valdiya warned that India's west coast is also not immune to tsunamis. He recalled that in 1945, Mumbai, then known as Bombay, was lashed by tsunami waves triggered by an earthquake on the Makran coast, which is another subduction zone in the Arabian Sea.

Most experts have grown up with the belief that there is no geological fault in peninsular India. But Valdiya said this is not true.

He said his latest work had confirmed that many of the so-called "lineaments" that have been identified by remote sensing and field work along the western coasts of Kerala, Karnataka and Maharashtra "are actually geological faults" potentially capable of causing earthquakes.

"Some of these faults are active, some inert and some are 'locked,' meaning there is no movement taking place," Valdyia said.

There are hundreds of faults with no movement, "but certainly stresses and strains are accumulating there and when the limit is exceeded there will be an earthquake," he said.

According to Valdiya, "one cannot simply locate nuclear plants on the basis of today's hazard zoning map that is based on past occurrences of earthquakes".

"Just because a fault has not been identified, it doesn't mean the fault does not exist," he stressed.

Valdiya added that his work has also led to the discovery of a seismic "hotspot" in the Indo-Gangetic plain that needs to be addressed. His findings will soon be published in the journal of the Geological Society of India.

According to C.P. Rajendran of the Centre for Earth Sciences at the Indian Institute of Science in Bangalore, the biggest earthquake threat to India is from the Himalayas.

"One of our major concerns should be the 2,500-km long Himalayan plate boundary that extends from the northwest to northeast, a zone that hosts potential fault lines that could generate both large and great earthquakes (magnitude-7 and above)," he said.