Tsunami Science

What is a Tsunami?



So you've come to research some tsunami science or have been wondering, "What is a tsunami?" If you want to make an oceanographer cringe, try calling a tsunami a "tidal wave". This is scientifically incorrect. Unlike a tidal wave, tsunamis are very different in how they are formed and travel at sea. A tsunami is not the result of changes in the tides.

A tsunami is caused by underwater land movement, most often earthquakes. When sudden land movement displaces water vertically, a tsunami is formed. Out at sea and far away from the coast, a tsunami is relatively unnoticed. In a sense, one can almost think of it as a wave traveling under the sea. On the surface, one may notice a swelling of the ocean. But as the tsunami approaches shoreline, and the depth of the ocean decreases, the tsunami can take on the appearance more of an onrushing wave, but with much more water behind it.

Unfortunately, it is difficult to have much of a warning of an incoming tsunami. Tsunami science has become more intriguing as scientists and oceanographers today are developing tools and models that help to track potential tsunamis, but the leadtime of the warning is still quite short. There are a few ways to recognize a potential tsunami threat:

  • You are near the coast and feel an earthquake.
  • You notice the water level on the shoreline begins to fall dramatically. This happens just prior to a tsunami reaching shore. Unfortnately, if you are witnessing this event firsthand, it usually means you only have seconds or possibly minutes before the tsunami makes land.
  • There are often a series of smaller tsunami waves prior to the largest one rolling in. The largest wave is often follow by a series smaller one as well. The term "smaller" is relative to the largest wave however. These "smaller" waves can still do serious damage.
  • You notice animals along the coast begin to retreat inwards. This has been observed in areas that are subject to tsunami threats. It is believe that many types of animals can either sense the oncoming wave or hear it.
  • As noted for the animals above, you actually hear the wave coming. Again, at this point it is often too late to take much action.

Tsunami's travel at incredible speeds, so visual or audio clues to an inbound wave are usually going to be too late to allow you to prepare for it. To fully comprehend the impact of a tsunami, take some time to research the 2007 Indian Ocean Earthquake on the internet. This event on December 26, 2004 sent 100ft tsunamis crashing against many of the shorelines boarding the Indian Ocean, killing over 225,000 people.


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