Scientists find tsunami clues, no final answer

The scientists presented their findings over the weekend to Sri Lanka’s Minister of Science and some 100 engineers, academics and other dignitaries after a hectic week of observation and analysis amid chaos and misery.

One location on the other side of the planet with a similar risk profile kept coming up in the discussion — the Pacific Northwest. Bruce Jaffe, a US Geological Survey scientist from Santa Cruz, California, on a US team that assessed the east coast, showed the Sri Lankans slides depicting research that revealed ancient tsunami sand deposits on Washington’s coast. Jaffe noted that these findings, made less than two decades ago, ultimately awakened Northwest residents to their own risk of major subduction quakes and killer waves.

The Sri Lankans have no definitive written record of a previous tsunami, but the scientists emphasised that this doesn’t mean it hasn’t happened before here.

Many in the crowd came hoping that the visiting scientists would provide them with information and specific recommendations on how to accurately predict a tsunami and completely protect against the next one. But without better sea-floor mapping and near-shore topography, Liu said, it will be difficult to completely explain the variable and unpredictable behaviour of the killer wave.

Undersea canyons off the coast of Sri Lanka, one near Galle in the south and another near Trincomalee in the northeast, may have played major roles in the tsunami’s behaviour, Liu said. In the especially tragic case of Galle, he said, such a canyon likely focused the wave into a greater force for destruction.

Of interest more to the scientists, perhaps, than for this crowd seeking immediate were all the reports that the ocean here in Sri Lanka receded before the arrival of the deadly high walls of water. Given the assumed nature of the quake and the standard theory of tsunami behaviour, Liu said, this should have happened only in Indonesia or other areas east of the fault. ‘‘According to many eyewitnesses, this isn’t what happened,’’ Liu said. ‘‘Maybe, the standard model is not quite right.’’

Costas Synolakis, a University of Southern California tsunami researcher, who will be visiting India next, cited deep-ocean tsunami detectors as a critical element for a warning system in the Indian Ocean. — NYT News Service