Six and a half years down the line, India boasts of having a robust tsunami warning system, which can not only issue alerts to India but every neighbouring country within 10 minutes of any big quake, capable of triggering a tsunami.
The Rs 125-crore tsunami warning centre at the Indian National Centre for Ocean Information Services in Hyderabad encountered 25-30 major earthquakes in the last three years.
“So far we are 100 per cent right and have not issued any false alert,” INCOIS director Sateesh Shenoi told Deccan Herald. India does not face any threat from the 8.9 earthquake in Japan even though the scientists at the centre are monitoring the ocean waves round-the-clock.
“We are monitoring everything from Philippines to Hawaii and are in touch with other tsunami warning centres around the globe since 2007,” said Shailesh Naik, secretary, Ministry of Earth Sciences, who was INCOIS director when the Indian system was being built.
The data for the Indian system is being fed by a network of four bottom pressure recorders placed on sea beds and a network 50 tidal gauges, maintained by the Survey of India and National Institute of Ocean Technology (NIOT) in Chennai.
Even though the initial plan was to have 12 bottom pressure recorders, Naik said four is adequate at the moment. In case the need arises in future, more BPRs can be added to the network to further improve the quality of warning.
At the tsunami warning centre six mammoth flat panel displays and a network of 12 computers round-the-clock monitor the seismic activities in the Indian Ocean region and studies data generated by the pressure recorders and tide gauges.
An ideal tsunami warning system requires data from all sources because relying on seismic signals alone can be erroneous. Since only a small proportion of strong earthquakes produce tsunami, a warning system based solely on seismic data is prone to producing false alarms.
The data from ocean is transmitted to INCOIS using INSAT links. A high-level of redundancy has been built into the data communication system to avoid single point failure.
“For issuing alert, we follow a procedure. If there is no threat, we also inform the country that there will not be any tsunami from a particular earthquake,” Shenoi said.