(1)An Undersea Earthquake - is the most common form of tsunami formation, typically generating the most destructive tsunamis. The earth is constantly moving on large tectonic plates. When these tectonic plates move past each other, collide and/or slide under one another (subduction), an earthquake results. This is what happened with the recent tsunami that devastated Southern Asia. Here, a massive earthquake in the Indian Ocean measuring 10.0 on the Richter scale jolted the seabed causing the sudden displacement of a very large volume of water. The earthquake temporarily produces a fluctuation in the mean sea level of a specified area. Waves quickly form as the displaced water tries to recapture equilibrium by filling the vacuum that was created. It should be noted that not all earthquakes generate tsunamis. Usually, it takes an earthquake with a Richter magnitude exceeding 7.5 to produce a destructive tsunami.
(2)Landslides – resulting in rockfalls, icefalls, or underwater (submarine) landslides or slumps can generate displacement of water to create a tsunami. More often than naught, submarine landslides are often caused by earthquakes, large and small, therefore strengthening the force of an earthquake induced tsunami. The most notable example of a landslide-induced tsunami can be traced to Southern France in the 1980’s where the movement of a significant amount of earth for the construction of an airport triggered an underwater landslide, which resulted in destructive tsunami waves hitting the harbor of Thebes.
(3)Volcanic Eruption - Although relatively infrequent, violent volcanic eruptions represent also impulsive disturbances, which can displace a great volume of water and generate extremely destructive tsunami waves in the immediate source area. Volcanic disturbances can generate waves by the sudden displacement of water caused by a volcanic explosion, by a volcano's slope failure, or more likely by a phreatomagmatic explosion and collapse and/or engulfment of the volcanic magmatic chambers. The majority of tsunamis that occur in the Pacific Ocean happen around the “Ring of Fire” Area surrounding the Hawaiian Islands. The periphery has also been dubbed the 'Ring of Fire' because of the extraordinarily high number of active volcanoes and seismic activity located in the region. Since 1819, over 40 tsunamis have struck the Hawaiian Islands. One of the largest and most destructive tsunamis ever recorded was generated in August 26, 1883 after the explosion and collapse of the volcano of Krakatoa (Krakatau), in Indonesia. This explosion generated waves that reached 135 feet, destroyed coastal towns and villages along the Sunda Strait in both the islands of Java and Sumatra, killing 36, 417 people.
(4)Extraterrestrial Collision – Tsunamis caused by extraterrestrial collision (i.e. asteroids, meteors) are an extremely rare occurrence. Although no meteor/asteroid induced tsunami have been recorded in recent history, scientists realize that if these celestial bodies should strike the ocean, a large volume of water would undoubtedly be displaced to cause a tsunami. Scientists have calculated that if a moderately large asteroid, 5-6 km in diameter, should strike the middle of the large ocean basin such as the Atlantic Ocean, it would produce a tsunami that would travel all the way to the Appalachian Mountains in the upper two-thirds of the United States. On both sides of the Atlantic, coastal cities would be washed out by such a tsunami. An asteroid 5-6 kilometers in diameter impacting between the Hawaiian Islands and the West Coast of North America, would produce a tsunami which would wash out the coastal cities on the West coasts of Canada, U.S. and Mexico and would cover most of the inhabited coastal areas of the Hawaiian islands.
Ed tech
Wednesday, June 23, 2010
Tsunami
A tsunami (Japanese: 津波 [tsɯnami], lit. 'harbor wave'; English pronunciation: /(t)suːˈnɑːmi/ (t)soo-NAH-mee) or tidal wave is a series of water waves (called a tsunami wave train[1]) caused by the displacement of a large volume of a body of water, such as an ocean or a large lake. Tsunamis are a frequent occurrence in Japan; approximately 195 events have been recorded.[2] Due to the immense volumes of water and energy involved, tsunamis can devastate coastal regions.
Earthquakes, volcanic eruptions and other underwater explosions (detonations of nuclear devices at sea), landslides and other mass movements, bolide impacts, and other disturbances above or below water all have the potential to generate a tsunami.
A tsunami (Japanese: 津波 [tsɯnami], lit. 'harbor wave'; English pronunciation: /(t)suːˈnɑːmi/ (t)soo-NAH-mee) or tidal wave is a series of water waves (called a tsunami wave train[1]) caused by the displacement of a large volume of a body of water, such as an ocean or a large lake. Tsunamis are a frequent occurrence in Japan; approximately 195 events have been recorded.[2] Due to the immense volumes of water and energy involved, tsunamis can devastate coastal regions.
Earthquakes, volcanic eruptions and other underwater explosions (detonations of nuclear devices at sea), landslides and other mass movements, bolide impacts, and other disturbances above or below water all have the potential to generate a tsunami.
Tsunami
A tsunami (Japanese: 津波 [tsɯnami], lit. 'harbor wave'; English pronunciation: /(t)suːˈnɑːmi/ (t)soo-NAH-mee) or tidal wave is a series of water waves (called a tsunami wave train[1]) caused by the displacement of a large volume of a body of water, such as an ocean or a large lake. Tsunamis are a frequent occurrence in Japan; approximately 195 events have been recorded.[2] Due to the immense volumes of water and energy involved, tsunamis can devastate coastal regions.
Earthquakes, volcanic eruptions and other underwater explosions (detonations of nuclear devices at sea), landslides and other mass movements, bolide impacts, and other disturbances above or below water all have the potential to generate a tsunami.
A tsunami (Japanese: 津波 [tsɯnami], lit. 'harbor wave'; English pronunciation: /(t)suːˈnɑːmi/ (t)soo-NAH-mee) or tidal wave is a series of water waves (called a tsunami wave train[1]) caused by the displacement of a large volume of a body of water, such as an ocean or a large lake. Tsunamis are a frequent occurrence in Japan; approximately 195 events have been recorded.[2] Due to the immense volumes of water and energy involved, tsunamis can devastate coastal regions.
Earthquakes, volcanic eruptions and other underwater explosions (detonations of nuclear devices at sea), landslides and other mass movements, bolide impacts, and other disturbances above or below water all have the potential to generate a tsunami.
Tuesday, June 15, 2010
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