Tsunami

A tsunami is a series of large waves that are created in the ocean or another large body of water, usually caused by an earthquake, a landslide, a volcanic eruption, or meteorite impact into the body of water. When a tsunami hits a coastline, it capable of causing a massive amount of destruction. Many people refer to tsunamis as “tidal waves” but since tsunamis are not created or effected by tide, this is not a proper term to use.

Tsunami waves are different from a typical wave that are seen on the shoreline. Most normal waves are formed from wind that occurs offshore and are very small. Tsunamis, on the other hand, can be about 100 km across while they are in the middle of the ocean. Tsunamis are very fast too, traveling at about 700 km an hour and can be very hard to spot because in the open ocean, they are roughly a meter high. As a tsunami approaches the shore and comes to shallow water, the wave slows down and grows a great deal in height. Even though tsunamis are not easily seen at sea, they will grow many meters tall and hold a great deal of energy. When tsunamis reach the coast line, a rapid fall in tide may occur and the illusion of the tide rising may be seen. Eventually, a series of waves will hit the shore at a height of up to 30 meters.

Minutes before a tsunami hits the shore, the water will retreat further than usual (called drawback), making the ocean floor visible. When the first wave hits, it is usually followed by a series of other waves that can be larger and more powerful than the first. When the tsunami reaches land, the temporary rise in sea level is called a “run up”. Tsunamis reach the shoreline anywhere from ten to sixty minutes apart. The danger of further tsunamis after the first one hits can last for several hours. About 80 percent of all tsunamis occur in the Pacific Ocean, but they are possible in any large body of water, including lakes.

Tsunami Warnings:
When a person observes drawback, this can be a fair warning that a tsunami is about to hit a shoreline. Many people who have observed drawbacks have survived by immediately running for higher ground or high floors on close buildings. Drawback does not always occur however, such in the case of the 2004 Indian Ocean Tsunami. There was no draw back experienced on the African coast because the wave moved downwards on the eastern side of the fault line that it originated.

Tsunamis cannot always be predicted, even when earthquakes occur in the ocean. Based upon factors observed by scientists about the earthquake, they may or may not issue tsunami warnings to the surrounding coasts. Automatic systems using cutting edge technology can detect whether or not an earthquake has caused a tsunami, giving ample time to save many lives.