Tsunami (Japanese: tsu = port, nami = wave, which literally means "big waves in the harbor") is the transfer of water bodies caused by changes in sea surface vertically with a sudden. Changes in sea level can be caused by an earthquake centered under the sea, underwater volcanic eruptions, underwater landslides, or or a meteor hit the ocean. Tsunami waves can propagate in all directions. Power contained in the tsunami wave height is fixed to the function and kelajuannya. 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 caused 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 name that links the tsunami by an earthquake under the other. But until the 20th century, knowledge about the cause of the tsunami is still very minimal. Research is still underway to understand the causes of tsunamis.
The texts of geology, geography, and oceanography in the past called tsunamis as "seismic sea waves".
Some of the meteorological conditions, such as tropical cyclones, storm surges can cause the so-called meteor tsunami wave height several meters above normal sea. When the storm made landfall, the shape can resemble the tsunami, although not a tsunami. Wave could inundate the land. This storm surge had flooded the Burmese (Myanmar) 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 are building Indian Ocean Tsunami Warning System (IOTWS), which will be based in Indonesia.
Historical evidence suggests that megatsunami is possible, which caused some islands to sink
Table of contents
Terminology____________________________________________
The word tsunami comes from the Japanese tsu means harbor and nami means wave. Tsunamis often Japanese. Japanese history has recorded at least 195 tsunamis occurred.
On several occasions, equated with the tsunami tidal waves. In recent years, this perception has been declared no longer appropriate, particularly within the research community, because the tides have nothing to do with the tsunami. This perception is popular because the first appearance of the tsunami that resembles a high tide.
Tsunamis and tidal waves are equally produces water waves that move to the mainland, but in the tsunami, the wave motion is much larger and longer, so memberika impression as a very high tide. Although the notion that equates with "the tides" includes "resemblance" or "similar character" to surge, this understanding is no longer appropriate. The tsunami not only limited to the harbor. Because of the geological and oceanographically highly not recommend to use the term.
There are only a few local language which has the same meaning with these destructive waves. Aazhi Peralai in Tamil language, ie beuna or Alon buluëk (according to dialect) in the language of Aceh is an example. For the record, in Tagalog version of Austronesian, the main language in the Philippines, Alon means "wave." On Simeulue Island, west coast of Sumatra, Indonesia, in Bahasa Defayan, smong mean a tsunami. While in Language Sigulai, Emong mean a tsunami.
The cause of the tsunami__________________________________
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.
The speed of tsunami waves depends on the depth of the sea where the waves occurs, where the speed can reach hundreds of kilometers per hour. When the tsunami reaches the shore, its speed will be around 50 km / h and its energy is very damaging coastal areas in its path. In the midst of the tsunami wave height sea only a few centimeters to several meters, but when it reaches shore wave height can reach tens of meters due to a buildup of the water. When the tsunami reaches the coast of the mainland will crawl away from the coastline with a range of several hundred meters can even be a few kilometers.
This vertical motion can occur on the earth fault or the fault. The earthquake also occurred in the subduction area, where the oceanic plate menelusup 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. 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 megatsunami 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 a strength of at least 6.5 on the Richter Scale
- An earthquake with a pattern of reverse fault or fault down
Early Warning System____________________________________
Many cities around the Pacific, especially in Japan and Hawaii, has a tsunami warning system and evacuation procedures for dealing with the tsunami event. The tsunami can be predicted by various institutions in various parts of the world of seismology and tsunami processes can be monitored through a device that is on the basis of sea surface terknoneksi atu dengansatelit.
Pressure recorders on the ocean floor together denganperangkat floating in the sea buoy, 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.
Until now, the science of tsunamis is quite developed, although the occurrence is still a lot that has not known with certainty. Epicenter of an earthquake under the sea and the possibility of tsunami events can be quickly calculated. Modeling tsunami that both have managed to estimate how big the tsunami wave height in the source area, speed and time penjalarannya reached the coast, how the tsunami height at the beach and how far the marinade that may occur on the mainland. However, due to natural factors, such as the complexity of topography and bathymetry around the coast and the diverse patterns of land cover (both plants, buildings, etc.), the estimated tsunami arrival time, altitude and distance immersion tsunami still could not be modeled accurately.
Tsunami Warning System in Indonesia______________________
Government of Indonesia, with the help of donor countries, has developed a Tsunami Early Warning System of Indonesia (Indonesian Tsunami Early Warning System - InaTEWS). This system is centered on Meteorology, Climatology, and Geophysics (BMKG) in Jakarta. This system allows BMKG send a tsunami warning in case of an earthquake that could potentially cause a tsunami. The system is currently being refined. In the future, this system will be able to issue a warning level 3, in accordance with result of Decision Support Systems (Decision Support System - DSS).
Development of Tsunami Early Warning System involves many parties, both central government agencies, local governments, international agencies, non-governmental agencies. Coordinator of the Indonesian side is the Ministry of Research and Technology (RISTEK). Meanwhile, the designated agency and responsible for issuing INFO EARTHQUAKE and TSUNAMI WARNING is BMKG (Bureau of Meteorology, Climatology and Geophysics). The system is designed to be able to issue tsunami warnings within a period of 5 minutes after the earthquake.
Early Warning System has 4 components: Knowledge of Hazard and Risk, Forecasting, Warning, and Reaksi.Observasi (Monitoring seismic and sea level), Integration and Dissemination of Information, Preparedness.
How it Works___________________________________________
A Tsunami Early Warning System is a series of complex work systems involving many parties and international, regional, national, regional and empties into the community.
In the event of an earthquake, then the incident was recorded by means Seismograph (earthquake recorder). Earthquake Information (strength, location, time of occurrence) BMKG sent via satellite to Jakarta. Furthermore, BMG will release QUAKE INFO delivered through technical devices simultaneously. Seismic data included in the DSS to take into account whether the earthquake has the potential to cause a tsunami. The calculation is done based on millions of modeling scenarios that have been made in advance. Then, BMKG may issue TSUNAMI WARNING INFO. This seismic data will also be integrated with data from other early warning system equipment (GPS, buoys, OBU, Tide Gauge) to confirm whether a tsunami had actually been formed. This information is also forwarded by BMKG. BMKG deliver tsunami warning information through multiple intermediary institutions, which include (Local Government and the Media). These intermediary institutions that transmit warning information to the public. BMKG also convey information via SMS alerts to mobile phone users who are registered in the database BMKG. Earthquake Info delivery mode for now is via SMS, Fax, Telephone, Email, RANET (Internet Radio), FM RDS (Radio have facilities RDS / Radio Data System) and through the Website BMG (www.bmg.go.id) .
Experience as well as many field events proved that although many sophisticated equipment being used, but the most effective tool to date for the Tsunami Early Warning System is RADIO. Therefore, to the people who live tsunami-prone areas are asked to always stand prepared to listen to FM RADIO Tsunami early warning news. Other tools are also known potent Radio Communication Between People. Organizations that take care of the RAPI (Radio Inter-Population of Indonesia). Why Radio? simple answer, because when an earthquake off the lights often no electricity. The radio can operate with batteries. Also because of its small size, can carry around (mobile). Radius komunikasinyapun relatively sufficient.
Source: Wikipidea
No comments:
Post a Comment