I think on the west coast of the United States they have buoys that can detect a tsunami. If a tsunami is detected, they relay that warning to stations on the coast. There wasn't any such system in the Indian Ocean, nor is there one in the Atlantic, at least on the U.S. east coast.

>I was wondering - the tsunami was said to advance at a speed of ca. 500 km/h. Wouldn't that give enough time to warn people in coastal regions to move to higher areas? I think it should be possible to observe such a monster from sattelites or something - or perhaps suspect that something might happen, as soon as the earthquake is detected.