The images from the Indian Ocean tsunami that left nearly 300,000 dead or missing last December are striking. Amateur video shot in Phuket, Thailand, for example, shows huge ocean waves ripping across beachfront swimming pools and crashing through hotel lobbies.

“All of those videos were shot from the upper floors of hotels; [the buildings] survived,” said Gerard Fryer, a geophysicist and tsunami expert at the University of Hawai’i at Manoa in Honolulu.