Difference between revisions of "Tsunami"
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A tsunami, tidal wave, or seismic (related to earthquakes) sea wave is a larger-than-normal wave that is created by the displacement of water. The term tsunami comes from the Japanese word for "harbour wave" and can be caused by several things that quickly displace huge amounts of water. These include earthquakes, volcanic eruptions, underwater landslides, meteorite impacts, glacier calvings (when a piece of an glacier breaks off to form an iceberg) or explosive detonations. Although many people may call them tidal waves, this name is not a true description of what they are. Tsunamis might appear to be very rapidly incoming and high tides, but tides are produced by the gravitational pull of the moon while tsunamis are produced by water displacement. We use the Japanese term because Japan has the longest recorded history of tsunamis.
How they Work
Tsunamis can be started by several different things that quickly displace huge amounts of water. The most common of these is an underwater earthquake. Others include volcanic eruptions, underwater landslides, meteorite impacts, glacier calvings, or explosive detonations. The earthquake (or other cause) pushes a great volume of water out of its way, creating a large wave that can travel more than 800 km/h! Although the length of the waves is long and far-traveling, the height may be no more than 1 meter. This means that tsunamis can be undetectable in deep water.
As the wave approaches shallow water and the shore, it slows down and gets higher, creating a high wall of water that has a powerful smashing force. The water crashes into the shore and damages or destroys anything in its way. It also floods the land, causing flood damage and carrying debris with it for kilometers.
- 2004 - The Indian Ocean earthquake and tsunami killed 230,000 people
- 1908 - The Messina earthquake and tsunami killed more than 123,000 people
- 1783 - The Calabrian earthquakes and tsunamis killed more than 40,000 people
- 1755 - The Lisbon earthquake and tsunami killed more than 40, 000 people