You all have heard the word Tsunami, right? The tsunami is one of the most devastating natural disasters. Maybe before the tsunami disaster in the western tip of Indonesia, namely in Aceh precisely on December 24, 2004, the word tsunami is a foreign word for the people of Indonesia. And since that time, Indonesian people are getting to know the name of the tsunami. Even the word tsunami if alighted on the ear can cause trauma and deep sadness for the families left behind.
Tsunami is a type of natural disaster in the form of waves of sea water which is very large and hit the mainland. The word Tsunami comes from Japanese, which is "Tsu" which means harbor and the word "Nami" which means wave. If interpreted, the word tsunami means big waves in the harbor. Scientifically, a tsunami is defined as a displacement of water bodies caused by sudden changes in sea level vertically.
A tsunami wave is a type of wave that can move in all directions up to a distance of thousands of kilometers. The damage caused by the tsunami waves will be stronger if in an area close to the center of the disturbance. Tsunami wave height at first in the high seas was not too high at only about one meter. However, the speed possessed by this wave can reach 500 to 1000 kilometers / hour, of course this speed is the same as the speed of the jet plane. Because of this incredible speed, the ship that was in the ocean until not felt the presence of this wave.
Conversely, when getting closer to shore, the speed of this tsunami wave decreases which is only about 35 to 50 kilometers / hour. However, the height of the waves will increase even reaching a height of 20 meters. With these heights, of course it is very easy for tsunami waves to strike land to distances of miles. Now that's a brief overview of the tsunami waves.
Then the question is why is the name of this disaster called a tsunami taken from Japanese? This is because the country of Japan is a country that is very vulnerable to an earthquake, the earthquake was the one that caused a big sea wave or tsunami.
Factors Causing Tsunamis
The tsunami was a terrible natural disaster. We cannot deny that the portion of land affected by the tsunami will be destroyed because of the strength possessed by the tsunami waves. The occurrence of a tsunami is usually not a single natural disaster. That is, usually a tsunami does not come on its own suddenly. But usually there is a cause, so there was a tsunami. Several natural events caused the tsunami. The factors that cause a tsunami include the following:
1) Underwater Earthquake
Underwater earthquakes are the most common causative factor that can cause tsunamis. Underwater earthquakes cause a lot of vibrations that will drive a tsunami wave. Underwater earthquakes are the main cause of tsunamis in the world. Nearly 90% of tsunami disasters that occur in the world are caused by earthquakes that occur under the sea. This earthquake that occurs under the sea is a type of tectonic earthquake caused by the tectonic plates meeting. Although underwater earthquakes are the main cause of tsunamis, it does not mean that all underwater earthquakes can cause tsunamis.
2) Underwater Volcano Eruption
The occurrence of volcanic eruptions under the sea is one of the main causes of the occurrence of the Tsunami. The ocean that fills two-thirds of the earth's surface holds many secrets. Actually not only on land that has active volcanoes, but under the sea has many active volcanoes. Volcanoes that are still active under the sea really have a great potential to explode. As a result of a large explosion of an underwater volcano this can certainly cause a tsunami.
Several tsunami events caused by volcanic eruptions in Indonesia such as the eruption of Mount Krakatau in 1883. These events caused a terrible tsunami that swept the area around the Sunda Strait.
3) Occurrence of Underwater Landslides
The occurrence of landslides under the sea is one of the causes of the Tsunami. Tsunamis caused by landslides under the sea are often called Tsunami Dynamic Submarine Landslides. The shape of the surface of the sea resembles land, just as on land we can find hills and ravines, well in the ocean we can find it. Underwater landslides are generally caused by tectonic earthquakes or underwater mountain eruptions. This strong vibration caused by a landslide can cause a tsunami. In addition to tectonic earthquakes and volcanic eruptions, collision plates that are under the sea can also cause landslides.
4) The existence of a Meteor Hit
The cause of the tsunami that is likely to occur is due to the impact of meteors or celestial bodies. Although there has never been a document that states that there was a tsunami due to a meteor hit, but this certainly can happen. As simulated by sophisticated computers, that if there are large meteors (because small meteors will usually burn out in the earth's atmosphere) for example more than a kilometer in diameter, it can cause devastating natural disasters. If a meteor falls at sea it will cause a very large tsunami that has a height of up to hundreds of meters.
Signs of a Tsunami Disaster
There are several signs that indicate that a tsunami will occur. Therefore, the community must be vigilant and take appropriate actions immediately. Some signs of a tsunami are as follows:
The occurrence of an earthquake or vibration centered from under the sea The water suddenly recedes. Unusual signs of nature, such as strange animal behavior. For example a swarm of bats comes out in the daytime with an unnatural amount, birds fly whose baisas are never like that and so on. There was a loud roar from inside the sea.
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