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Kutch quake was more than 180 years
in the making: Expert

It took Mother Nature more than 180 years to cook the Republic Day earthquake, spread over a volume of 4.5 million cubic kms.

The first inkling that the quake was ready to strike came exactly a month ago. The Allah Bund, which emerged out of the earth's womb as a five-metre-high, 20-metre-deep and 60-km-long landmark following the 1819 earthquake in western Kutch, was rocked by a 'precursor' tremor of 4.2 magnitude on the Richter Scale on December 26 last year.

The Gujarat government should have set up monitoring stations soon after this quake, said Dr J G Negi, eminent geophysicist and former Director-grade scientist at the National Geophysical Research Institute, Hyderabad.

Dr Negi said just a few seconds before the major quake, Kutch was rocked by multiple tremors.

The focus of the killer quake was located 20 km below the surface and its 'built-up' area (or volume) was 4.5 million cubic kms spread in the form of a triangle, at one end of which was Delhi, at another the Aravali Ridge with the Gulf of Kutch and Cambay making up the third corner.

Dr Negi, who studied the 1967 Koyna earthquake and was subsequently awarded the prestigious Shantiswaroop Bhatnagar Award, the highest honour in the scientific arena in India, said the Republic Day quake was being studied by scientists and seismologists all over the world.

Four days after the event, the Geological Survey of the United States calculated that the January 26 quake measured between 8.0 and 8.1 on the Richter scale. The figure was later revised to 7.7.

The June 16, 1819 quake had submerged an area of nearly 5,000 sq kms while raising 1,500 sq kms of land in Kutch district. Since the latest quake measured 7.9 on the Richter Scale, the changes wrought by it would be several times more extensive, he added.

Dr Negi said this would change the state's very complexion in terms of the earth underneath.

For example, Ahmedabad, with its alluvial, sedimentary terrain of sand up to a depth of 20 kms, has now been 'softened up', in what is a case of 'partial collapse'. It will take some time to ascertain the quake-triggered changes in the topography of Gujarat, he added.

Studies have shown that there was a very important discontinuity in Gujarat's crust, making the areas around it crystalline or brittle. This ensures building up and storing of energy over a long period of time, which triggers earthquakes of devastating magnitudes, Dr Negi explained.

UNI

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