The Tsunami of 2004

The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred on December 26, 2004, off the west coast of Sumatra, Indonesia. The quake itself is known by the scientific community as the Sumatra-Andaman earthquake. The resulting tsunami itself is given various names, including the 2004 Indian Ocean tsunami, Asian Tsunami, Indonesian Tsunami, and Boxing Day Tsunami. The earthquake was caused by subduction and triggered a series of devastating tsunami along the coasts of most landmasses bordering the Indian Ocean, killing more than 225,000 people in eleven countries, and inundating coastal communities with waves up to 30 meters high. It was one of the deadliest natural disasters in recorded history. Indonesia, Sri Lanka, India, and Thailand were the hardest hit. With a magnitude of between 9.1 and 9.3, it is the second largest earthquake ever recorded. This earthquake had the longest duration of faulting ever observed, between 8.3 and 10 minutes. It caused the entire planet to vibrate as much as 1 cm and triggered other earthquakes as far away as Alaska. The plight of the many affected people and countries prompted a widespread humanitarian response. In all, the worldwide community donated more than $7 billion in humanitarian aid.

The History of Tsunamis

There have been about 25 Tsunamis occuring in the past century, and they are not rare either. Out of these 25, most were reported in the Asian-Pacific region- more commonly known as Japan. The Tsunami in 2004 caused around 350,000 deaths and all lot more injuries. As early as 426B.C. the Greek historian Thucydides inquired in his book "History of the Peloponnesian War" about the causes of Tsunamis and argued that it could be only be explained as a consequence of ocean earthquakes. He was the first in history to correlate quakes and waves in terms of cause and effect. The Roman historianThe Roam historian Ammianus Marcellenus described the typical sequence of a tsunami, including an incipient earthquake, the sudden retreat of the sea and a following gigantic wave, after the 365 A.D. tsunami devastated Alexandria.

Characteristics of a Tsunami

All storms and weather conditions have characteristics. Well, so do Tsunamis. These are a few of the big characteristics of a Tsunami. Normal everyday wind waves have the wavelength (from crest to crest) of about 100 meters and a height of about 2 meters. But, a Tsunami in the deep ocean is about 200 kilometers and travels at 800 kilometers per hour. As the Tsunami approaches the coast and the water gets shallow, the wave is compressed due to wave shoaling and its forward travel slows below 80 kilometers per hour.

Signs of an Approaching Tsunami

In almost all weather conditions, there are signs as to say "uh oh a storm is coming" or "warning a tornado is coming this way", so you would think there are signs of an approaching tsunami. Well there are actually no signs of Tsunami's, but there are other things that just might help you guess that a Tsunami might be coming. A few things to watch out for are: if a earthquake occurs near shallow water, then likely you will get a Tsunami. Another thing to watch out for is, if you are in a coastal area and the water starts to drawback more then normal, and you hear a sucking noise then that is another sign. If the first part of the Tsunami is a trough (drawback) and its not the crest of the wave, then you will likely see parts of the waters that would normally be submerged.

The causes of Tsunamis

Tsunami's have been around for many years, they are deadly water waves that kill many people and demolish cities. Just a few years ago in 2004, we had a terrible Tsunami that did so much damage that they are still repairing. Some causes of Tsunami's are when the destructive plates move abruptly and vertically displace the overlying water. Subduction zone related earthquakes generate the majority of all Tsunami's. At the beginning of all Tsunami's, the water level only swells 300mm above normal sea level. A Tsunami can occur at any state of a tide, and even at low tide will still inundate coastal areas if the incoming waves surge high enough. Some Tsunami's can reach all the way across an ocean. There are some smaller Tsunami's that happen in Japan that can devastate nearby coasts within 15 minutes. Could you imagine, a small Tsunami can completely demolish a coast in 15 minutes, could you imagine how fast a big Tsunami could demolish a coast! In the 1950's it was hypothesized that larger Tsunami's were created by landslides, explosive volcanic eruptions, and impact events when they contact water.