How are tsunamis tracked

How are tsunamis tracked?

In 1965, after a tsunami hit the pacific coastline in the United States, a warning sytem was created. The headquarters for this is known as the Pacific Tsunami Warning Center (PTWC) located in Honolulu, Hawaii. Its responsibility is to issue warnings on any tsunami like activity to any Pacific Ocean emergency centers. Although the risk of tsunamis are possible in the Atlantic and Indian Oceans, the Mediterrean, Caribbean, and Black Seas, there are no warning systems for these oceans!

The first step of a tsunami warning system is keeping track of seismic waves and the sea level. The next step is to compare all data on any previous tsunamis that may have happened in the area before.The last step is to make sure there is good communication between monitoring stations, the warning centre and at-risk states.

A good example of needing tsunami warning systems all over the world is when the tsunami hit Sri Lanka in December 2004. By chance, this tsunami was recorded by the Jason satellite that was flying over the Indian Ocean. Scientists did not know that the satallites could pick up low wave amplitudes of the tsunamis until that day. The satallite is designed for ocean research so it was not able to send warning before the tsunami hit Sri Lanka. This tsunami was caused by a major shift in a well known fault lnecausing increased pressure on other parts of the fault. This tsunami had the same amount of energy as 23,000 atomic bombs and caused 150,000 people to die in one day.

just a cool picture oh a tsunami

deadliest tsunami in history

Giant forces that had been building up deep in the Earth for hundreds of years were released suddenly on December 26, shaking the ground violently and unleashing a series of killer waves that sped across the Indian Ocean at the speed of a jet airliner.

By the end of the day more than 150,000 people were dead or missing and millions more were homeless in 11 countries, making it perhaps the most destructive tsunami in history.

The epicenter of the 9.0 magnitude quake was under the Indian Ocean near the west coast of the Indonesian island of Sumatra, according to the USGS, which monitors earthquakes worldwide. The violent movement of sections of the Earth's crust, known as tectonic plates, displaced an enormous amount of water, sending powerful shock waves in every direction.
The earthquake was the result of the sliding of the portion of the Earth's crust known as the India plate under the section called the Burma plate. The process has been going on for millennia, one plate pushing against the other until something has to give. The result on December 26 was a rupture the USGS estimates was more than 600 miles (1,000 kilometers) long, displacing the seafloor above the rupture by perhaps 10 yards (about 10 meters) horizontally and several yards vertically. That doesn't sound like much, but the trillions of tons of rock that were moved along hundreds of miles caused the planet to shudder with the largest magnitude earthquake in 40 years.

tsunami facts

Beginning of a tsunami wave
Sometimes plate boundaries abruptly deform and displace the overlying water vertically. Subduction earthquakes are efficient in generating a tsunami. In the 1940s, an earthquake measuring 7.8 on the Richter scale gave rise to a tsunami. Explosive volcanic action, landslides and impact events can also start a tsunami. The water wave may reach 50 to 150 meters and cover a height of 500 meters on local mountains. A "megatsunami" is caused by large landslides. The displaced water mass moves under the effect of gravity. This water radiates across the ocean similar to ripples in a pond.

Signs that a tsunami is approaching

• if an earthquake takes place near a body of water, it means that a tsunami will follow in a short time
• if the water along the shoreline recedes dramatically and exposes usually submerged areas it should be inferred that this is the trough of the tsunami and a crest will follow after a few seconds or minutes
• some large animals like elephants hear the noise of the tsunami and move in the opposite direction towards inland
• computer models can also foresee tsunami arrival and impact depending upon knowledge of the event that caused it and the shape of the oceanbed
• there is a loud roar similar to a train or aircraft

Tsunami warning system
Such systems comprise of two parts:

• a network of sensors to detect tsunamis
• a communications infrastructure to provide alarms for evacuation of coastal areas

There exist international and regional tsunami warning systems. The underlying principle used in both is that tsunamis move at a speed of 0.14 to 0.28 km/sec while seismic waves of 4 km/sec. Thus, when an earthquake is confirmed, there is sufficient time to predict a tsunami.

Reducing the effect of a tsunami

• Japan builds tsunami walls of 4.5 meters height in populated coastal areas
• floodgates and channels are built to redirect the water from the tsunami
• a tree cover is made on the shore

These measures slow down and moderates a tsunami. However, they cannot totally prevent the destruction and loss of life.

Records related to tsunami

• The maximum death toll due to tsunami has been 283,000 in 2004 in the Indian Ocean.
• The second largest has been 100,000 in 1755 in Portugal, Morocco and the United Kingdom.
• The third largest is 70,000 in 1908 in Italy.

In the Indian Ocean, an earthquake of 9.0 magnitude on the Richter scale took place. The epicenter was close to the west coast of the Indonesian island of Sumatra. The Earth's tectonic plates moved violently and displaced a large quantity of water. Powerful shock waves were sent in all directions. At some places, these waves reached a height of 9 meters. Within a span of some hours, killer waves hit the coasts of 11 Indian Ocean countries and devastated properties from Thailand to Africa.

Other tsunami facts
At the deepest point in the ocean, Tsunamis can have a speed of 600 mph. Close to the shore, this speed reduces to 30 to 40 mph. This energy of the wave's speed is transformed to increased height and sheer force. These waves can be as long as 100 kilometers and one hour apart. They can cross huge oceans without much loss of energy. Tsunamis can take place at any time in night or day. They can move up the rivers and streams that end up in the ocean. Tsunamis move faster than a human being.

Megatsunami
If the waves range from 40 meters to more than 100 meters, they are called as a "megatsunami". When they reach land, they acquire more height due to the force of impact. They are also called as "iminami" or "wave of purification"

what is a tsunami

The term tsunami comes from the Japanese, meaning "harbor" (tsu, ) and "wave" (nami, ). (For the plural, one can either follow ordinary English practice and add an s, or use an invariable plural as in the Japanese.) Tsunami are common throughout Japanese history; approximately 195 events in Japan have been recorded.

Tsunami are sometimes referred to as tidal waves. In recent years, this term has fallen out of favor, especially in the scientific community, because tsunami actually have nothing to do with tides. The once-popular term derives from their most common appearance, which is that of an extraordinarily high tidal bore. Tsunami and tides both produce waves of water that move inland, but in the case of tsunami the inland movement of water is much greater and lasts for a longer period, giving the impression of an incredibly high tide. Although the meanings of "tidal" include "resembling" or "having the form or character of" the tides, and the term tsunami is no more accurate because tsunami are not limited to harbours, use of the term tidal wave is discouraged by geologist and oceanographer.

A tsunami can be generated when convergent or destructive plate boundaries abruptly move and vertically displace the overlying water. It is very unlikely that they can form at divergent (constructive) or conservative plate boundaries. This is because constructive or conservative boundaries do not generally disturb the vertical displacement of the water column. subduction zone related earthquakes generate the majority of all tsunamis.

Tsunamis have a small amplitude (wave height) offshore, and a very long wavelength (often hundreds of kilometers long), which is why they generally pass unnoticed at sea, forming only a slight swell usually about 300 mm above the normal sea surface. They grow in height when they reach shallower water, in a wave shoaling process described below. A tsunami can occur at any state of the tide and even at low tide will still inundate coastal areas if the incoming waves surge high enough.