TSUNAMI


Tsunami

A tsunami or tidal wave is a series of water waves (called a tsunami wave train) caused by the displacement of a large volume of a body of water, usually an ocean, but can occur in large lakes. Tsunamis are a frequent occurrence in Japan; approximately 195 events have been recorded.[3]  Due to the immense volumes of water and energy involved, tsunamis can devastate coastal regions. It caused by changes in sea surface vertically with a sudden. Changes in sea level could be caused by an earthquake centered under the sea, underwater volcanic eruptions, underwater landslides, or meteor hit the ocean. Tsunami waves can propagate in all directions. Power contained in the tsunami wave height is fixed to the function and speed. In the deep ocean, tsunami waves can propagate with the speed of 500-1000 km per hour. Equivalent to the speed of aircraft. Deep-sea wave height is only about 1 meter. Thus, the wave speed is not felt by the ship which was in the middle of the sea. When approaching the coast, the tsunami wave velocity decreases to about 30 km per hour, but its height was increased to reach tens of meters. Tsunami waves can go blow up to tens of kilometers from the beach.  Damage and casualties that occur because of the Tsunami can be caused by a blow of water and materials carried by the flow of tsunami waves.
The negative impact causes by tsunamis are destroying everything in its path. Buildings, plants, and resulted in human casualties and causing inundation, salt water contamination of agricultural land, soil, and clean water.
The Greek historian Thucydides was the first to relate tsunami to submarine earthquakes,[4][5]  but understanding of tsunami's nature remained slim until the 20th century and is the subject of ongoing research. Many early geological, geographical, and oceanographic texts refer to tsunamis as "seismic sea waves."
Some meteorological conditions, such as deep depressions that cause tropical cyclones, can generate a storm surge, called a meteotsunami, which can raise tides several meters above normal levels. The displacement comes from low atmospheric pressure within the centre of the depression. As these storm surges reach shore, they may resemble (though are not) tsunamis, inundating vast areas of land. Such a storm surge inundated Burma in May 2008.
The area around the Pacific Ocean has the Pacific Tsunami Warning Centre (PTWC) issued a warning that if there is threat of a tsunami on this region. The area around the Indian Ocean is building Indian Ocean Tsunami Warning System (IOTWS), which will be based in Indonesia.
Historical evidence suggests that mega tsunami is possible, which caused some islands to sink
The landslide that occurred on the seabed and volcanic debris can also lead to disruption of sea water which can generate a tsunami. The earthquake caused perpendicular movement of the earth layer. As a result, the sea rose and fell abruptly so that the balance of sea water which is above them disturbed. Similarly, cosmic objects or meteor that fell from above. If the size of a meteor or landslide is big enough, can occur mega tsunami reach hundreds of meters high.

The quake that caused tsunami

     * An earthquake centered in the middle of the sea and shallow (0-30 km)
     * An earthquake with strength of at least 6.5 on the Richter scale.
     * An earthquake with a pattern of reverse fault or fault down.



Examples of tsunami that have occurred:

• 1 November 1755 - The tsunami destroyed Lisbon, the capital of Portugal, and claimed 60,000 lives.
• 1883 - On August 26, Krakatoa eruption and tsunami killed more than 36,000 inhabitants.
• 2004 - On 25-26 December 2004, the massive earthquake that caused the tsunami claimed over 250,000 lives in South Asia, Southeast Asia and Africa. The height of the tsunami of 35 m,
• 006-17 July, the earthquake that caused tsunami in southern Java, Indonesia, and the maximum was found 21 meters tall on the island of Nusakambangan. People lives of more than 500 people. And comes from the southern town of Ciamis
• 2007 - 12 September, Bengkulu, Eating deaths of 3 people. The height of Tsunami is 3-4 meters.
• 2010-27 February, Santiago, Chile
• 2010-26 October, Mentawai Islands, Indonesia






































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