Tsunami: The killer wave
Tsunamis are one of the most dangerous natural disasters, because they transfer so much energy with them that they can knock down entire buildings. One of the strongest tsunamis recorded ever was the tsunami in 2004 in the Indian Ocean, it had such force that it could compare to 23,000 Hiroshima type atomic bombs. The earthquake wasn’t sudden it was building up for 100 years, and were released on December 26. Not only one wave was released but an entire series of killer waves, the scientists couldn’t have predicted this tsunami because the energy was being stored up for 100 of years and it didn’t have the energy to be on the radars on the scientists. There were a large number of deaths, 150,000 people were dead or missing, and millions of people were left homeless in 11 countries.
Because tsunamis are surface waves they need a medium to travel through. They also have elements of positive interference because they combine the energy of several waves; this creates a large and deadlier wave. Tsunamis are classified by scientists as shallow water surface waves; this means that it is a surface wave, which is a wave that occurs on the surface of liquid , and the shallow water waves means that the wave occurs in depths of less than or one half of their wavelength. The interesting thing is that a tsunami will always be a surface no matter how deep the water below it is ,this is so because its wavelength is always greater than its wave height. Shallow water waves differ from deep water waves by one mayor thing, for shallow water waves their speed is controlled only by the water depth. In the open ocean, a tsunami can travel up to 470 kilometers per hour, but because of their low height (usually less than 1 meter) and very long wavelength, ships rarely ever notice them. However the opposite goes for when the killer wave moves into the shore, because of the friction with the shallow ocean floor the speed is decreased and so is the wavelength, but the height increases greatly. The energy in a wave has to be redistributed; this means that the wave height increases while the speed and the wavelength decreases. The best way to simulate this would be to observe small waves on the beach, they are small until they reach the shore where their height increases and the eventually break. On a tsunami when its wave height increases, the wave forms a “wall” of water; if the wall is high enough it can be very destructive and cause tremendous damage. Witnesses say that tsunamis can reach tremendous heights of 65 meters, and can continue miles inland.
Tsunamis are dangerous and unpredictable; a modern day scientist can predict a tsunami on the day it is going to occur or 2-3 days before. This doesn’t leave the local authorities much time to evacuate all of the citizens. Earthquakes are a driving force behind tsunamis, an underwater earthquake is the starting point of the tsunami, and because of the shaking in the ground large waves start to form on the ocean. Unfortunately there is no way to stop a tsunami once it is set into motion; this means that there aren’t any barricades or other ways of stopping it. When officials detect an earthquake that is shallow and is underwater they send distress signals to the endangered area. The seismologists and the tsunami department can only rely on the seismograph and seismometer to warn them of earthquakes. There is however one flaw that could be fatal in this plan that is that not all underwater earthquakes trigger tsunamis, this leaves the seismologists with the toughest decision, weather to warn local authorities and tell them to evacuate the area or is the earthquake a hazardless underwater earthquake.
1965 was a big year for the development of tsunami warning systems, the United Nations scientific, educational and cultural organization decided to expand their current tsunami system at Ewa beach, Hawaii. This decision initialized the PTWC or the Pacific Tsunami Warning Center, a group that operated with the help of different weather services, especially those of the US. The job of this organization is to detect major earthquakes in the Pacific Ocean and determine whether or not tsunamis are going to generate from those movements, they also must warn the people in the potentially affected region so that they can minimize the damage. Currently the two mayor organizations for tsunami warning systems are the ITWS, the international tsunami warning system and the PTWC. They both use a common way of detecting tsunamis. They have carefully positioned seismic stations that measure the movement in the earth’s crust, if the movement is strong enough to generate a tsunami. They also monitor wave patterns and pressure gauges are placed in the ocean to detect changes of more than 1 cm.
Even though the way the ITWS monitors tsunami activity may sound perfect it does have some flaws. The system is constantly updated but can always miss a tsunami that has been building up for months and then when it starts to develop into a full scale tsunami it is too late to evacuate the region. This mistake has happened in the past and will probably happen in the future, the largest consequence of this flaw happened in 2004 when the largest tsunami in history struck in the Indian Ocean. Hopefully researchers will be able to develop an even more effective way of foreseeing tsunamis and potentially even preventing them.
Bibliography
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3:"Tsunami and Predicting Tsunamis." Science.jrank.org. Web.
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