Kamis, 07 April 2011



Tsunami (derived from Japanese, literally means "big waves in the harbor") is a wave that occurs after an earthquake, seismic sea, volcanic eruption, or meteor hit the ocean. Power every tsunami is fixed, the function of altitude and fast. With that, when the wave approached the shore, its height increases while fast decrease. The wave is moving at high speed, almost no effect can be felt by a ship (for example) when crossing the water in, but increased to a height of 30 meters or more. Tsunamis can cause erosion damage and fatalities in coastal areas and islands. Most cities around the Pacific Ocean, mainly in Japan but also in Hawaii, have warning systems and evacuation procedures if the tsunami had been predicted.

Tsunami will be observed by various seismological institutions around the world and its development is monitored via satellite. Evidence suggests mega tsunami not impossible occurrence, which caused some islands to sink. Tsunamis can occur if an interruption occurs that causes the movement of large amounts of water, such as volcanic eruptions, earthquakes, landslides or meteorite that fell to earth. However, 90% of the tsunami is an earthquake under the sea. In recording the history of some of the tsunami caused by the volcano eruption, for example when the eruption of Mount Krakatoa. Vertical movement on the earth's crust, can lead to the ocean floor rise or drop suddenly, which resulted in disruption of water balance that is above them. This resulted in the energy flow of sea water, which when it reached the coast into a large wave that caused the tsunami. This vertical motion can occur on the earth fault or the fault. Earthquakes also occurred in many areas subduction, where oceanic plates go down the continental shelf.

The landslide that occurred on the seabed and volcanic debris can also lead to disruption of sea water which can generate a tsunami. 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. Bottom pressure recorder that uses a "buoy" as a communication tool, can be used to detect the waves that can not be seen by human observers at sea. Simple system that was first used to provide early warning of impending tsunamis ever attempted in Hawaii in the 1920s. Later, a more sophisticated system was developed again after the great tsunami of April 1, 1946 and May 23, 1960.

The United States makes the Pacific Tsunami Warning Center in 1949, and connecting to data networks and international commemoration in 1965. One of the system to provide early warning tsunami, CREST Project, installed at the West coast of the United States, Alaska, and Hawaii by the USGS, NOAA, and the Pacific Northwest Seismograph Network, and by three university seismic networks. Now, in Aceh also has installed a tsunami early warning tool, but the performance is still questionable. Because some day yesterday, the alarm sounds and tools the Acehnese cause panic. The alarm was false and no tsunami was coming. These events occurred twice and was otherwise damaged equipment. Until now, the tsunami forecast system is still an imperfect science, in the sense of not fully detect the tsunami event. Epicenter of an earthquake under the sea and the possibility of tsunami events can be quickly calculated. Modeling tsunami that both have successfully estimate how big the mass transfer of water occurs. However, due to natural factors that often unmodelled and unpredictable, frequent false warnings.

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