Earthquakes and hurricanes make headlines more often, but tsunamis are often deadlier. They mostly happen around the edges of the Pacific, set off by earthquakes and volcanoes. Ninety-five percent of the world's seismic activity happens in the Pacific, which is why Sunday's devastation around the Indian Ocean was such a surprise.
The disaster began a few hundred miles off the coast of Indonesia, with a magnitude 9 earthquake. That quake was the largest recorded since one in 1960 in Chile.
If it had happened on land, it would have caused massive devastation, but the effects, most likely, would have been fairly local.
Instead, the shock wave — spreading from beneath the ocean floor — sent a giant bulge of water all the way to the surface, six miles above. The ripple effect quickly spread, reaching Sri Lanka in two hours, the coast of India in three hours and the easternmost parts of Africa in six.
On the open ocean, a tsunami can move at 500 miles an hour, but the waves are surprisingly small. If you are on a ship you might not even feel them as they race by.
As they get into shallow water, though, they are slowed dramatically by friction from the bottom — and the force has nowhere to go but up.
"In the open ocean it was about 3 feet; on the coastline it's about 20 [feet] to 30 feet," said Eddie N. Bernard, director of the Pacific Marine Environmental Laboratory, part of the National Oceanic and Atmospheric Administration.
The people affected by this atrocity are in desperate need of aid. If you are interested in helping, please feel free to visit http://www.usaid.gov/, and http://www.networkforgood.org/topics/international/earthquake/tsunami122604.aspx.