by Eva Amsen

It didn’t take long for the world to realize the devastating effects of the tsunami that hit the coasts of southern Asia on December 26, 2004. Fund raisers quickly collected money to rebuild life at the miles of shore line that were hit. Natural disasters such as this are, sadly, unavoidable. The only possible preventive measure is an early warning system.
There was no warning system in place in the Indian Ocean at the time of the tragedy, but calculations afterwards have been able to map what happened, and this can be an important aide in developing a warning system.

The December tsunami started as an earthquake at the ocean floor near Sumatra, miles away from the places where it caused the most damage. At the point of the earthquake, the sea floor moved 5 meters vertically, and 11 meters across.

An earthquake at the bottom of the ocean causes a water displacement: the tsunami waves are small out on the ocean and travel fast in the deep water. Once they get in shallower waters closer to the coast, the waves move slower, and can reach heights of up to ten or twenty meters. However, even tsunamis that are not as high can do a lot of damage due to the direction they’re traveling in. Unlike regular waves that come and go, the tsunami hits once and hits hard.

Simulations and calculations are unfortunately not accurate enough to predict exactly where and if a tsunami will hit. Although it seems obvious in retrospect that this earthquake (of magnitude 9.0!) resulted in such devastating waves, not all earthquakes on the sea floor lead to a tsunami. On top of that, it’s hard to predict exactly where a tsunami will hit. Any warning system where an earthquake at sea triggers an alarm would probably lead to many false alarms. Nevertheless, a warning system for the Indian Ocean, much like the system currently used in the Pacific Ocean, is in the works right now. This may seem a bit redundant, but in the long term a tsunami will hit again. Maybe the next one will not be as violent, maybe it will hit somewhere else, but it will happen, and timely warnings can save a lot of lives.

Read more:
Tsunami! (second image)
How the shape of ocean floors can affect speed and height of tsunami
In Wake of Disaster, Scientists Seek Out Clues to Prevention

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