The rolling disaster started with a massive, magnitude–nine undersea earthquake off Indonesia, triggering monstrous walls of water.
Sri Lanka took the deadliest hit with at least 12,000 killed there and thousands more perishing in India, Thailand and Indonesia.
At least eight Americans died and hundreds are unaccounted for. All along the coast, from Asia to Africa, it's a sight of devastation and despair.
Millions of people left homeless by the tsunami are now in desperate need of shelter, clothing, and clean water. Relief efforts have begun pouring in, but so far they've only scratched the surface of what could be the costliest disaster on record.
Jan Egeland, UN Emergency Relief Coordinator said, "The cost of the devastation will be in the billions of dollars...probably many billions of dollars."
The numbers are staggering: more than 12,000 people killed in Sri Lanka, some 5,000 in Indonesia, and 4,000 in India. Red Cross officials estimate more than 23,000 deaths in the region overall, but thousands are still missing, and bodies continue to wash ashore.
The 9.0 magnitude earthquake struck off the island of Sumatra early Sunday, and unleashed deadly tidal waves. Tourists from around the world, vacationing in Thailand and Sri Lanka, found themselves trapped by the fast–moving water. Scores of travelers did not survive.
One witness said, "All we heard was this almighty bang and the next thing the place was flooded. It was up to there."
U.S. officials are still trying to contact hundreds of Americans who remain unaccounted for in the region. They're also sending at least $15 million in immediate aide.
Colin Powell, U.S. Secretary of State said, "This is indeed an international tragedy, and we're going to do everything we can to assist the nations that have been affected in dealing with this tragedy."
President Bush has sent written condolences to the leaders of nations recovering from the tragedy, as the U.S. now takes the lead in the relief operation.
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Read below for Tsunami FAQ's, Safety Tips, and Did You Know Facts
Tsunamis: Frequently Asked Questions
Q: What Is a Tsunami?
A: A tsunami (pronounced “soo-nah-mee”) is a series of waves of extremely long wave length and long period generated in a body of water by an impulsive disturbance that vertically displaces the water. The term tsunami was adopted for general use in 1963 by an international scientific conference. Tsunami is a Japanese word represented by two characters: "tsu" and "nami." The character "tsu" means harbor, and the character "nami" means wave. In the past, tsunamis were often referred to as "tidal waves." The term "tidal wave" is a misnomer. Tides are the result of gravitational influences of the moon, sun, and planets. Tsunamis are not caused by the tides and are unrelated to the tides; although a tsunami striking a coastal area is influenced by the tide level at the time of impact.
Q: What Causes a Tsunami?
A: There are many causes of tsunamis but the most prevalent is earthquakes. In addition, landslides, volcanic eruptions, explosions, and even the impact of cosmic bodies, such as meteorites, can generate tsunamis.
Q: How Do Earthquakes Generate Tsunamis?
A: Tsunamis can be generated when the sea floor abruptly shifts and vertically displaces the overlying water from its equilibrium position. Waves are formed as the displaced water mass attempts to regain its equilibrium. The main factor which determines the initial size of a tsunami is the amount of vertical sea floor deformation. Not all earthquakes generate tsunamis. To generate tsunamis, earthquakes must occur underneath or near the ocean, be large and create movements in the sea floor. All oceanic regions of the world can experience tsunamis, but in the Pacific Ocean there is a much more frequent occurrence of large, destructive tsunamis because of the many large earthquakes along the margins of the Pacific Ocean.
Q: How Do Landslides, Volcanic Eruptions, and Cosmic Collisions Generate Tsunamis?
A: Any disturbance that displaces a large water mass from its equilibrium position can generate a tsunami. Generally tsunamis caused by landslides or volcanic eruptions dissipate more quickly than Pacific-wide tsunamis caused by some earthquakes and rarely affect coastlines distant from the source.
Q: How Do Tsunamis Differ From Other Water Waves?
A: Tsunami waves are shallow-water waves with long periods and wave lengths. (A wave is classified a shallow-water wave when the ratio between the water depth and its wavelength gets very small. The speed of a shallow-water wave is equal to the square root of the product of the acceleration of gravity (32ft/sec/sec or 980cm/sec/sec) and the depth of the water.) Shallow water waves are different from wind-generated waves (the waves many of us have observed on the beach). Wind-generated waves usually have period (time between two succesional waves) of five to twenty seconds and a wavelength (distance between two successional waves) of about 50 to 600 feet (15 to 200 meters) A tsunami can have a period in the range of 10 minutes to 1 hour and a wavelength in excess of 700 km (430 miles).
Q: What Happens to a Tsunami as it Approaches the Shore?
A: "As the tsunami wave reaches the shallower water above a continental shelf, friction with the shelf slows the front of the wave. As the tsunami approaches shore, the trailing waves pile onto the waves in front of them, like a rug crumpled against a wall creating a wave that may rise up to 30 feet before hitting the shore. Although greatly slowed, a tsunami still bursts onto land at freeway speeds, with enough momentum to flatten buildings and trees and to carry ships miles inland." (From: Waves of Destruction by Tim Folger, Discover Magazine, May 1994, pp. 69-70)
Q: What Are the Impacts of a Tsunami?
A: Tsunamis can savagely attack coastlines, causing devastating property damage and loss of life.
Q: Are Tsunamis All the Same?
A: No. U.S. coastal communities are threatened by tsunamis that are generated by both local earthquakes and distant earthquakes. Local tsunamis give residents only a few minutes to seek safety. Tsunamis of distant origins give residents more time to evacuate threatened coastal areas but increase the need for timely and accurate assessment of the tsunami hazard to avoid costly false alarms. Thus, U.S. residents in Alaska can experience a local earthquake and tsunami while residents of Hawaii and the west coast may experience this disaster as a distant tsunami. Similarly, west coast residents can experience a local tsunami that may also have an impact on the distant states of Alaska and Hawaii. Of the two, local tsunamis are more devastating.
Q: Can Tsunamis Be Predicted?
A: Since science cannot predict when earthquakes will occur, they cannot determine exactly when a tsunami will be generated. But with the aid of historical records of tsunamis and numerical models, scientists can get an idea where tsunamis are most likely to be generated.
Tsunami Safety Tips
Did You Know?
Source: http://www.noaa.gov (National Oceanic and Atmospheric Administration Web site) contributed to this report.