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・TsunamiTohoku region Pacific Ocean earthquake (the name of the earthquake) or East Japan great earthquake disaster (the name of the disaster) occurred at 14:46:18 on March 11, 2011.The Japan Meteorological Agency revised up magnitude (M) indicating the scale of the earthquake to 9.0 from 8.8 at about 0:55 on the afternoon of 13th. In the damage of the disaster destruction of this casualties and the building, the tsunami was a big cause. Therefore, I place the findings about the tsunami here. ＜ Wave energy ＞ Wave energy Wave Coastal Engineering＞Wave energy The energy of the wave is proportional to square of the wave height from the site mentioned above. Wave height is vertical length between the valley of the wave and the heap of waves. In other words the energy is 4 times if height is double. In other words the power of the tsunami means that it can be measured in height. But this energy is average energy per unit area of water surface of 1 wavelength. The wave height of the tsunami is inversely proportional to 4 roots of the depth of the water and 2 roots of the waterway width. When depth is deep, and the width of the waterway is large, the tsunami height is low, and the power of the wave weakens. Oppositely, when depth of the water is shallow, and the width of the waterway is narrow, the tsunami height is high, and the power of the wave strong. The biggest tsunami in Japan was said to be Meiji Sanriku tsunami of 1896. It has been estimated that the height at that time is about 38.2m. The height of this tsunami is 38.9 meters in Miyako-shi, Iwate. The height of tsunami of this earthquake was biggest in Japan in observation history. ＜ Difference between usual wave and tsunami. ＞ Mentioned above wave energy is average energy per unit area of water surface of 1 wavelength. More the wavelength and numbers of the wave besides height, are necessary to store more vast energy of earthquake. In other words, it is necessary to expand the surface area of the wave in entire surface of sea. The tsunami is caused by large-scale seabed upheaval or subsidence for short time. Therefore it is supposed that the number of waves are few early in the tsunami outbreak. In other words, wavelength is needed for expanding the surface area of the wave. The wavelength of the tsunami is actually longer than usual wave. It is difference of usual wave and the tsunami. Therefore, the sea level seems to rise visually. And wave continues to surge continuously. As a result, it is thought that breakwater is got over. And it is thought that the wave surges to the inland. In other words, tsunami is not sporadic like normal wave. It is continuous. In other words, the wave height of tsunami is higher than normal wave, and wavelength of tsunami is longer than normal wave. ＜ Picture of the tsunami ＞ East Japan great earthquake disaster. Massive tsunami attacked the town of Kamaishi. Tsunami. "The car seems to be consumed by wave!" The car which runs away. Tohoku region Pacific Ocean earthquake. The picture that the car which the woman got into is likely to be swallowed for a tsunami. 【East Japan great earthquake disaster.】Moment of the tsunami. Most shocking. Earthquake tsunami in Japan Tsunami 1 that swallows everything. （2011.3.11 Iwate prefecture. Noda village.） Tsunami TSUNAMI - Earthquake (3/11) 20110411 The moment that Kesennuma city is swallowed by massive tsunami. Massive tsunami. Tsunami in japan. Oirase town. Moment of the tsunami.avi The momentary picture that the tsunami which an on-site person photographed desperately comes. 【Iwate, Ofunato】 The picture that the car which ran at front is swallowed for a massive tsunami. Patrol boat Matsushima climbing over a tsunami, provided by the Japan Coast Guard. Asian Tsunami Videos.com 2011.3.11 The massive tsunami animation which is not yet broadcasted in TV. ＜ Question and answer about the tsunami of the Japan Meteorological Agency. ＞ Question and answer about the tsunami of the Japan Meteorological Agency. The tsunami is greatly different from the normal wave that only the surface undulates like. Tsunami moves everything from the bottom of the sea to the sea surface. It is wave of having big energy and very fast speed. It is a custom to announce the tsunami warning in the shore when tsunami is predicted that the tsunami exceeds 0.2m. When the tsunami exceeds 1m, damage begins to appear in wooden houses. Tsunami warning (tsunami) is announced in the shore that predicted tsunami exceeds around 1m. Tsunami warning (massive tsunami) is announced in the shore that predicted tsunami exceeds around 3m. At this time, please evacuate to the safe hills immediately. Waves caused by the wind in the sea area is phenomenon of vicinity of surface of sea. The wavelength is from several meters to several hundred meters. On the other hand, the tsunami is generated by transformed seafloor topography by earthquakes. On the other hand, the tsunami is generated by transformed seafloor topography by earthquakes. As a result , the entire seawater in a wide peripheral range lifts and falls in short time. And, the wave that occurred is spread to the peripheral range, and it go. The wavelength of the tsunami is very long. It is from several kilometers to hundreds kilometers. Therefore, the tsunami surges in succession without force declining. Thereby tsunami runs up to altitude more than the height of the tsunami in the coast. Besides, tsunami have the characteristic that the height suddenly rises when it come in vicinity of shallow shore. Moreover, tsunami can continue to pull everything for a long time by strong power when tsunami retreat into sea. Therefore tsunami pulls in to underwater at a stretch the wreckage which tsunami destroyed. I heard that the tide goes down before the tsunami by all means, but it is a mistake. Depending on a way of the outbreak of earthquake, big wave may surge suddenly. As an example, there is the tsunami caused by the Tokachi offing earthquake of 2003. As another example, there are Sri Lanka tsunami and an Indian tsunami caused by the Sumatra offing earthquake of 2004. It varies according to building methods, but, about the house damage, begins to cause partial destruction from inundation around 1m in the wooden house. The inundation reaches the full-scale destruction at 2m. However, damage may be given by a direct hit of wreckage or ship or the wood even if the inundation is around 50cm. ＜ Personal opinion by having watched a picture. ＞ It was the feeling that sea level rose to rather than wave. The sea surface took time and gradually rose. It seemed that first wave calmed down. However, the second wave covered the first wave. And the tsunami added to force and height of sea level more and climbed over a dike at a stretch. Plural waves surged in a short time. The tsunami does not readily retreat. Many waves come and thereby the tsunami increases force and height and it goes to the inland. If it is plains, the wave seems to considerably reach to the inland. As a result, the ambulance and the fire engine was swallowed by tsunami. The tsunami swallows a town. In other words, tsunami swallowed debris, car, garbage, house, everything of town. And, it surged to the several kilos inland. In other places, the tsunami flowed backward along river. In other words, it is necessary to evacuate not only persons of seaside but also persons of inland low land. Fire and Disaster Management Agency：Preparedness to tsunami disaster ＜ Lesson of this tsunami. ＞ ・On plains of Natori-shi, tsunami surged to 6 kilometers of inland. In other words, on the plains, caution is necessary for inland on several kilos. ・The undertow is strong, and there is the power that even a cargo boat washes away. ・we have to wait for many hours until canceled the warning alarm of the tsunami. Because the following example exists. It is a Chile earthquake in 1960. The tsunami raided the Sanriku-kaigan coast about 22 and a half hours after the outbreak of the earthquake. The maximum height of the tsunami was 6m. Thereby 142 people died. It is state that transmit the tsunami of the earthquake of Peruvian coast in 2007. It is state that transmit the tsunami of the Tokachi-oki Earthquake in 2003. ・It is necessary to criticize to hill. Wooden house has been washed away or has been destroyed, by this tsunami. It was flooded up to the third floor also in the building of concrete. |
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