Tsunamis are natural disasters which can cause massive destruction. They are very fast and very large series of waves created when a large volume of water is shifted. The only way this can normally happen is a when a major earthquake, underwater landslide, or an equally high energy event occurs. They range from just a few inches to over 30 metres.
(Curiosity, Discovery. 2007)
Tsunami is a Japanese word which means “harbour wave” in English, but these terms were proved to be misleading. In the past, tsunamis were also called “tidal waves” and “seismic sea waves”.
The energy creating the tsunami travels under the water unlike normal waves which travel above the water. This makes tsunamis hard to detect as they make little appearance above the water. (Oracle ThinkQuest. 2011) The tsunami will only start appearing when it is closer to the shore, where the water is shallower. This gives the people at the shoreline little time to react to the impending tsunami. (Australian Government, Bureau of Meteorology. 2013) A tsunami can be generated by large disturbance in the ocean that moves and displaces large water mass. Some examples of these disturbances are volcanos, meteorites, explosions, and the most common, earthquakes. The earthquake must be at least a 6.75 magnitude on the Richter scale to cause a tsunami. (Enchanted Learning. 2010) In the case of earthquake-generated tsunamis, the water column is disturbed by the uplift of the sea floor. The water column will then travel in a ripple formation around the epicentre of the earthquake. The column will travel until it reaches a shoreline or it loses its energy. When the tsunami approaches a coastline, the column will grow in height, as the water get shallower. Almost 80% of the world's tsunamis occur in the Pacific Ocean. Tsunamis occur most often along countries which border the Pacific "Rim of Fire", or "Ring of Fire'. (Squidoo. 2013) One end of this region of high seismic and volcanic activity begins at New Zealand, heading northwest to Indonesia (completely bypassing Australia) and then west to Papua New Guinea and Indonesia, northeast along the Asian coastline, east to North America and then south along the western North American coastline.
A “Ring of Fire” is a roughly horse-shoe shaped, the Ring of Fire extends about 40,000km long. It is located along the Pacific Rim, surrounding the Pacific Ocean. (Squidoo. 2013) It runs from the tip of South America, up the coast of Chile, Peru, and Ecuador, through Central America and the west coast of Mexico, the United States and Canada. It extends to the southern coast of Alaska and along the Aleutian Islands, going on to Japan and the Philippines, ending in New Zealand. Indonesia is also part of the Ring of Fire, although some of its islands, such as Sumatra, are located in the Indian Ocean rather than the Pacific. (National Geography. 2013)
As tsunamis often occur due to underwater earthquakes, you can predict a tsunami when a earthquake strikes. Also, if the water is receding quickly and unexpectedly from a beach, also known as a drawback, there may a tsunami coming.( University of Washington Earth Space and Sciences, ESS. 2013)
There are different type of wave breakers found in many places to reduce the impact of waves and tsunamis. One of the wave breaker that can be found is the breakwater. The breakwater is a large piece of granite that is place in the middle of the ocean so as to reduce the energy of incoming waves and lessen the impact of tsunamis or waves on land. We can use this information to have a rough idea of what our wave breaker should be like.
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