Tsunami are a terrible natural disaster. Tsunamis are images of very large waves that crash into the land area. It cannot be denie that the land area affected by the wave sweep will be destroyed due to the strength of the wave. The occurrence of this tsunami is usually not a single natural disaster. That is to say, usually a tsunami does not come alone suddenly. But there is usually a delivery, so there was a tsunami. Some natural events are the cause of the tsunami. The things that delivered the tsunami included the following:
An earthquake is the most common thing that can cause a tsunami. The earthquake in question is certainly an underwater earthquake. Submarine earthquakes cause a lot of vibrations that will trigger tsunami waves. Submarine earthquakes are the majority cause of tsunami in the world. Nearly 90 percent of tsunami events in the world are caused by earthquakes that occur under the sea. The earthquake that occur under the sea is a type of tectonic earthquake that arises due to a meeting or collision of a tectonic plate. Although underwater earthquakes are the main cause of tsunamis, this does not mean that all underwater earthquakes can cause tsunamis. Submarine earthquakes will cause a tsunami if they meet several conditions, including the following:
The epicenter is located at a depth of 0 to 30 kilometers below sea level
An underwater earthquake that has the potential to cause a tsunami is when the epicenter is at depths between 0 and 30 meters below sea level. The more shallow the epicenter, the greater the chance for a tsunami. In other words, the more shallow the epicenter of the earthquake is, the greater the chance of a tsunami occurring. This is because the vibrations that are felt are also getting bigger and stronger, so the chances of a tsunami also getting stronger.
The earthquake that occurred on the scale was 6.5 on the Richter scale
The next criterion is that an earthquake must have a strength of more than 6.5 on the Richter scale. So for example there is a shallow earthquake, but the earthquake is small, it probably will not provide an opportunity for the tsunami. The earthquake that occurred with a minimum force of 6.5 on the Richter scale was considered to have been able to influence the waves of the sea water, which would eventually cause a tsunami. The experience of the disaster that occurred in Aceh in 2004, the earthquake that occurred has a power of about 9 on the Richter scale. To find out the magnitude of the earthquake used a measuring device for earthquake vibration.
The type of earthquake fault is an up and down fault
Another criterion that also supports the occurrence of tsunami waves is the type of fault. The magnitude of an earthquake that can cause a tsunami wave is a type of up and down magnification. The existence of these ups and downs can create a new wave which, if it moves to land, can produce a tsunami. This will be worsened if there is a fracture on the seabed, so that it will cause sea water to drop suddenly and become the forerunner of the tsunami.
Well, that’s some earthquake criteria that can cause a tsunami. Underwater earthquakes that do not comply with the above criteria then the chance of causing a tsunami is also small.
Submarine volcanic eruptions
The cause of the subsequent tsunami was the eruption of volcanoes under the sea. An ocean that fills two thirds of the earth’s surface holds a lot of secrets. We do not know much about the appearance of the underwater, that in fact not only land has active mountains, but also underwater has many active mountains. Some active mountains under the sea can potentially explode or erupt at any time. As a result of a large or strong eruption from this underwater volcano, it cause a tsunami.
One of the major events that described the tsunami caused by a volcanic eruption was in Indonesia, precisely to the west of the island of Java. The name Krakatoa erupted in 1883. This event cause a massive tsunami wave that swept the area around the Sunda Strait. In addition to the events of Mount Krakatau, in Indonesia there was also an eruption of Mount Tambora in 1815 which was in East Nusa Tenggara to result in the occurrence of the Maluku islands. Indonesia is a country that has many volcanoes so it is call the Ring of Fire. This makes Indonesia must always be vigilant because volcanic eruptions can occur at any time.
Underwater landslides occur
The cause of the next tsunami wave was the occurrence of landslides under the sea. A tsunami cause by an underwater landslide is called the Tsunami Submarine Landslide. Apparently landslides don’t only occur on land. As previously explained, the shape of the lower surface is like land. if on land we find hills and ravines, then in the sea too, so there is the potential for landslides. This underwater discharge is generally cause by a tectonic earthquake or a volcanic eruption. The strong vibration generated by this cycle can cause a tsunami. In addition to tectonic earthquakes and volcanic eruptions, collisions of plates beneath the sea can also cause landslides.
In 2008 a study was carries out in the Indian Ocean which mention the existence of a sea trough stretching from the island of Siberut to the coast of Bengkulu Beach where if the trough landslides there will be a tsunami on the west coast of Sumatra