The Hindu : Kerala News : Fresh tsunamis unlikely: Met

Online edition of India's National Newspaper
Wednesday, Dec 29, 2004

Kerala

Kerala

Fresh tsunamis unlikely: Met

By M. Harish Govind

THIRUVANANTHAPURAM, DEC. 28. The intensity of the aftershocks of Sunday's massive quake off Sumatra has come down and the likelihood of tsunami waves striking the Kerala coast again is very remote, according to the Met authorities here.

As many as 27 shocks had been reported on Sunday with an average magnitude of up to 7.5 on the Richter scale, but this dropped to 12 aftershocks on Monday, the average magnitude being between six and 6.5.

Today, as many as five aftershocks with magnitudes ranging between five and 5.5 were recorded till late in the evening. One tremor, recorded at 4.52 p.m., occurred 2,110 km away, close to the epicentre.

A bulletin said aftershocks of a magnitude of five to 5.5 on the Richter scale are unlikely to cause tsunami waves. However, those living in the coastal belt have been asked to stay away from vulnerable areas till 6 p.m. tomorrow. The sea would be moderately rough and fishermen were advised to refrain from venturing out into the sea in small fishing boats.

`No system to predict'

The Met Director, M. D. Ramachandran, said there is no system at present for predicting tsunami waves in the Indian Ocean. All undersea quakes of a high magnitude need not trigger such waves. Only if the quake generates a vertical upward or downward motion, thus displacing large volumes of water, do tsunami waves arise.

Sunday's quake, measuring nine on the Richter scale, was recorded on the seismic network, but without wave sensors, there was no way to determine whether it had triggered tsunami waves, or if it had, in which direction the waves would travel, Mr. Ramachandran said.

"In order to predict a strike, we would have to constantly monitor whether waves have been generated with the help of wave sensors mounted on buoys with the backup of a satellite network. At present, this is done only in the Pacific Ocean, where undersea quakes occur frequently," he said. According to a seismologist based in the Centre for Earth Science Studies (CESS) here, the tsunami disaster had highlighted the need for an early warning system on the lines of the system set up for the Pacific rim nations in 1965. This could be through regional cooperation among the South East Asian countries likely to be affected by future quakes in the Indian Ocean.

Lack of protocol

The official said scientists here simply lacked the experience or skill to respond to a tsunami event because a quake of such a magnitude had not occurred in the Indian Ocean before. Even a protocol on who should issue a warning, in what way it should be issued and what the nature of the warning should be, has to be evolved.

According to him, this lacuna becomes evident not only during a tsunami event, which is very rare, but also during a cyclone. "The super cyclone which hit Orissa in 1999 was being monitored and we even knew in which direction it was moving. Despite this, we could not warn the population in time or take adequate precautionary measures," he said.

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