Tsunami magnitude difficult to predict

Scientists can do a very good job of tracking the progression of a tsunami and predicting when it will arrive, but they have much more difficulty predicting how big it will be, experts said Saturday.

That disparity has become apparent following the magnitude 8.8 earthquake off the coast of Chile. Researchers from the Pacific Tsunami Warning Center in Hawaii predicted to within a few minutes when the tsunami -- a massive influx of water rather like a flash flood -- would arrive at Hilo. They also predicted that the wave height would range from 2 to 8 feet, and they were correct. But when the waves proved to be at the low end of the range, they were widely perceived as having blown the prediction.

Tsunami expert Harry Yeh of Oregon State University said the forecasters had to err on the side of caution. "Even if they knew deep in their heart that it probably wouldn't be large, it could be large," he said. "If they lost one life [because they underestimated the size of the tsunami], that would be a problem."

The biggest problem in predicting the size of a tsunami is in determining exactly how much energy was put into the ocean by an earthquake, and that is something that cannot be determined in the immediate aftermath of the event.

Continue reading Tsunami magnitude difficult to predict by Thomas H. Maugh II.