Aftershocks may cause further damage

By S. Nagesh Kumar

HYDERABAD, JAN. 26. Global seismological data when matched with recordings taken by the National Geographical Research Institute here has revealed that the devastating earthquake that struck Gujarat early this morning measured 7.9 on the Richter scale.

Dr. Harsh K. Gupta, Director of NGRI, told The Hindu that international data showed that the quake was marginally short of 8 on the Richter scale, which would have classified it as a ``great earthquake'', and was now termed ``a major earthquake''.

This makes it one of the biggest earthquakes in India. Only the earthquakes at Kangra in Himachal Pradesh in 1905 (8.2 on the Richter scale), Bihar-Nepal earthquake in 1934 (8.4) and the Shillong earthquake in 1897 (8.7) were bigger.

Asked why they had been unable to predict such a great earthquake, NGRI scientists said the Rann of Kutch, where the epicentre lay, was already classified as Zone V from the point of view of vulnerability to earthquakes. The Rann of Kutch experienced a quake of eight plus magnitude in 1819 but there was no great loss of human life because the epicentre was in the desert. But it left a six-metre high scar which can seen even today as it runs to a length of nearly 100 km. The Rann of Kutch lies in the Narmada-Son lineament, a fault which caused a major earthquake in Jabalpur a few years ago. (According to a PTI report, the last recorded earthquake in the Rann of Kutch was on June 16, 1819. Measuring 7.5 on the Richter scale, it created a 90-km long wall ``Allah Bund'' (wall of God), with a height of 4.3 metres and width of about 20 km.)

Till late in the afternoon, the residents of Bhuj experienced four or five aftershocks, some of them measuring over 5 on the Richter scale, Mr. Gupta said. He also did not rule out the possibility of aftershocks reaching a magnitude of 7.0 and causing further damage. People should take necessary precautions.

He said it was difficult to fix a time limit for the aftershocks as there were instances when they had continued for as along as one year. The NGRI was in touch with the Department of Science and Technology to pass on data from its seismological stations, he added.

Another seismological scientist said global data showed that the magnitude was ``8.0 on the Richter scale, confirmed''. The tremors were felt nearly 1,500 km away from the epicentre - as far as Nepal in the northeast, Pakistan in the northwest and Chennai in the south.

Ironically, the only earthquake of nearly equal magnitude also occurred on a day of national celebrations. On August 15, 1950 Assam was rocked by a quake of 8.0 magnitude but the population in the State being sparse and the dwelling structures largely quake-proof, the death toll was restricted to 1,526.

Dr. Indra Mohan, scientist (seismology), NGRI, said the epicentre of the Gujarat earthquake in geographical terms was 23.4 degrees north and 17.3 degrees east. It was located 20 km north-east of Bhuj, which bore the brunt of the tremors.

The two recent killer earthquakes at Killari village in Maharashtra's Latur district and Uttarkashi in what is now Uttaranchal measured 6.3 and 6.5 on the Richter scale. While the Killari quake claimed over 10,000 lives, the one in Uttarkashi left 1,500 dead. The biggest-ever earthquake in the earth's history occurred in the ocean off Chile in South America in 1960 when seismographs recorded a magnitude of 9.5 on the Richter scale.

`Collision of tectonic plates'

PTI reports:

The Himalayas may be far away from Gujarat, but the distant collision of tectonic plates under the mountain range may have played a role in causing today's devastating quake in Kutch, scientists say.

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