CHENNAI: The chilling visuals of tsunami devastating Japan on Friday brought back memories of December 26, 2004 to Chennaites-- and questions like how good our tsunami alert system is.Thanks to a global network of tsunami monitoring systems, Indian shores may not be caught unawares, but if maintenance of our tsunami buoys are anything go by, the Indian tsunami alert system is in a bad shape. As fishermen continue to vandalise tsunami buoys in the open seas, all that remains in the Bay of Bengal are two such buoys and one other in the Arabian Sea. These buoys sense tidal variations and send out signals to a satellite that alerts the ground stations.Several buoys deployed in the Indian seas in last decade had been vandalised by fishermen who break open the buoys to take away metal parts. The Hyderabad-based Indian National Centre for Ocean Information Services (INCOIS), which runs the national tsunami warning centre, depends on tsunami buoys, among other things, for forecast.An NIOT official said 42 of the 50 meteorological buoys deployed for weather predictions in Arabian sea and Bay of Bengal were vandalised by fishermen. Over 160 meteorological, wave and tsunami buoys were retreived out of 240 by NIOT, mostly because of vandalism. In 2009, four damaged buoys were replaced, but those too were rendered useless soon. Fishermen pull out the glittering solar panel and the data collection systems based on a Bottom Pressure Recorder (BRP)."Ideally we should have 12 tsunami buoys in the Bay of Bengal and six in the Arabian Sea. Now we have just one in the Arabian Sea and two in the Bay of Bengal," an official said.NIOT director MA Atmanand confirmed that only three tsunami buoys were functional in the Indian waters, but maintained that they were sufficient. T Srinivasa Kumar, head, advisory services and satellite oceanography, INCOIS said tide guages also help in tsunami alerts. "Buoys and guages are deployed with enough redundancy to ensure a foolproof system. As we expect possible tsunami threats from locations like Sumatra which are well monitored, we don't need to worry," said Kumar. National Institute of Oceanography director SR Shetye said deployment and maintenance of tsunami buoys is a costly affair. "So far the earthquakes have happened in identified subduction areas far away from the Indian waters. Hence we may not need many tsunami buoys. Moreover, tide guages located along the Indian coast can also detect changes and send alerts," he said.The buoys transmit alerts through a real-time geo-stationary satellite INMARSAT to NIOT and INCOIS, which analyse the data. The ministry of home affairs shares the information through communication networks including telephone, e-mail and SMS.