CHIDAMBARAM: Though India is highly prone to seismic activity, it has not joined the International Federation of Digital Seismograph Networks (FDSN), Rainer Kind of Geo Forschungs Zentrum (Geo Research Centre), Potsdam, Germany has said.

Several countries, including Mexico, Iran, Thailand, Italy, the United Arab Emirates, the United States and Russia have become FDSN members while China has sought membership.

Prof. Kind, who is here to attend the 94th Indian Science Congress, told The Hindu on Saturday that the FDSN members had agreed to freely share data about seismic zones and seismic activities.

The IRIS Data Management Centre in Seattle was storing the data generated. Network codes had been assigned to the members to make the seismological data stream unique.

India was accessing the FDSN data, but was averse to contributing data to it. The FDSN's aim was to develop common minimum standards in seismography, for example bandwidth, and record statistics. Prof. Kind said a joint international mechanism would be a better bet to combat seismic-induced natural hazards than an isolated endeavour.

On the early warning system that would alert people in seismic zones to earthquake and tsunami, he said the FDSN was trying to make real-time determination both on location and magnitude. The warning could be made within seconds or minutes,depending upon the intensity and the facilities available. But, determining the magnitude was difficult. A breakthrough would be achieved, possibly by March 2007.

Within seconds of an earthquake, the rupture would spread to thousands of kilometres and wreak havoc; so, the determination of time factor was critical.

Much headway had been made in determining the epicentre of the earthquake.

Early warning system

Prof. Kind said countries in vulnerable areas ought to have a realistic real-time estimate of seismic events, for which installation of an early warning system was of utmost importance.

This called for setting up of as many real-time stations as possible.

As for the possibility of forewarning the people about tsunami, Prof. Kind said though seismic activity might trigger the tsunami, all seismological occurrences would not result in it. Therefore, the watchword was "preparedness." Again this depended upon the security policy of the countries concerned.

Earlier, in a presentation on `seismic hazards' at the Science Congress, Andrzej Kijko, Unit Head, Seismic Hazard Assessment and Mine Seismology, Council for Geoscience, Republic of South Africa, said the seismic catalogue was incomplete and uncertain. Over-estimation or under- estimation of seismic activity would be dangerous.

S.J. Duda, Institute of Geo Physics, University of Hamburg, Germany, dwelt on the linear and non-linear propagation of waves.

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