WASHINGTON: Just two years after a tsunami devastated communities around the Indian Ocean, U.S. scientists say another giant wave could strike off Sumatra within a few decades.

The December 26, 2004 tsunami that originated near Sumatra claimed nearly a quarter-million lives in 12 countries including India.

Researchers reported in Tuesday's issue of Proceedings of the National Academy of Sciences that they have found evidence that wave-causing earthquakes have occurred in the region regularly, and parts of Sumatra south of the 2004 event could be threatened within 30 years.

The sea floor fault that caused the tsunami previously ruptured in 1797 and in 1833 and the researchers found a pattern or quakes about every 230 years. The results "confirm a substantial exposure of coastal Sumatran communities to tsunami surges," senior author Jose Borrero of the University of Southern California (USC) said in a statement. In particular, the coastal city of Bengkalu, with a population of 350,000, could face flooding up to several kilometres inland, he said. The study said offshore islands appear to somewhat shield the larger city of Padang, but it, too, could have a powerful wave.

In addition to USC, the study included researchers from California Institute of Technology.

Just last week the U.S. National Oceanic and Atmospheric Administration (NOAA) announced that it and the Government of Thailand had launched the first Deep-ocean Assessment and Reporting of Tsunami buoy station in the Indian Ocean to assist in detecting tsunamis. The buoy, funded by the U.S. Agency for International Development, will be followed by another next year as part of a set of 22 planned for the Indian Ocean to become part of a tsunami warning system. Until the regional tsunami warning capability is established, the NOAA's Pacific Tsunami Warning Centre in Hawaii and the Japan Meteorological Agency are providing tsunami advisory and watches alerts to 27 Indian Ocean countries. The individual countries then determine if and how they issue a warning to their people.

On the Net, PNAS is at http://www.pnas.org AP

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