Thursday, April 26, 2007

The Tsunami of 26 may 1983 in the se of japan

There was no sufficient time to issue a local warning. A warning was issued about 13- 15 minutes after the earthquake. It was too late. One hundred four persons died in Japan and three more in Korea. There was extensive destruction of houses, ships and port facilities.

Tsunami Generating Area and Tsunami Travel Times in the Sea of Japan and around the Japanese Islands ( in minutes) .
Subsequent surveys of the affected region along the western coast of Japan , sponsored by Japan's National Research Center for Disaster Prevention, documented the effects and runup heights of the tsunami waves. The results of these surveys are summarized here.

Tsunami Wave Heights - Estimated tsunami heights were 14 meters at Minehama, Honshu, 2-6 meters along southern Hokkaido and northern Honshu, up to 8 meters along the coast of Russia (USSR at the time), and ranged between 2-7.5 meters along the coast of South Korea.

Damages and Death Toll from the Tsunami - Many of the casualties and much of the tsunami damage occurred on the Oga Peninsula of the Akita Prefecture. Tsunami damage occurred as far away as the Yamaguchi Prefecture in southwestern Honshu, along the Japan Sea coast of Russia ( then USSR), and along the eastern and southern coasts of South Korea, where three people were killed.

The tsunami comletely destroyed Oga Peninsula in Japan
The Tsunami in the Akita Prefecture of Japan - The tsunami reached more than 11 m (max 14 m.) along the Akita Prefecture in the northern coast of Japan.There was extensive destruction of houses,buildins, ships and port facilities. It caused a number of fatalities. A total of 104 persons died. The tsunami destroyed 700 boats and 59 houses for a total of $800 million in property damage (1983 dollars).

The Effects of the Tsunami in Southern Korea - It took approximately 90 minutes for the first tsunami wave to travel across the Japan Sea and strike the east coast of the Korean Peninsula. This was the first tsunami to inflict heavy damage on the eastern coast of Korea since the 1741 Oshima-oshima tsunami. According to observations, the wave reached a height of 5 meters on Ullung Is.. Samchuk port, Geunduk, Yongwha beach and Yongwha port were also affected. Damage was particularly significant at the Imwon port, where tsunami runup height was about 3.6 m. On a coastal road close to Imwon the tsunami runup reached 5.1 m. Maximum runup of 7.5 m occurred at the upper part of the town along the river. Three persons were killed and twenty houses were damaged or destroyed.
At Wondok Town and Kangwon-do, a maximum tsunami height of 3.6-4.0m was recorded. Fishing boats were carried into the residential area, and a gas oil tank holding 130,000 litters was carried by about 10 meter. One person was killed at Tonghae City. The amount of damage in the Republic of Korea was estimated to be about 400 million won (about $500,000 - 1983 US dollars). Tide gauge recordings in South Korea showed the initial sea level movement to be rise at Pusan. Ulsan, Mukho (Tonghae City), Sokch'o, and Chodong (Ullung Island). However, at P'ohang port the tide gauge record indicates an initial drop in sea level.

Lessons Learned - Even in a country like Japan where there is considerable awareness of the tsunami danger, it is very difficult to issue local warnings when the earthquake source is so close to the coast. However, as a result of this tsunami, there was an increased effort for public education. Japan introduced a new regional system which offers a shorter lead time for tsunami warnings.

Historical Tsunamis in the Sea of JapanHistorical tsunamis generated by earthquakes along the possible boundary of the Eurasian and the North American plates, in the Sea of Japan, have been responsible for a great deal of destruction along the coastal areas of Japan, Russia and Korea. A review of archival material in Japan and Korea will undboubtedly reveal the occurrence of many historical tsunamis in the Sea of Japan - perhaps as many as 6-8 events spaced apart in time and location. Most noteworthy of the known historical events are the following.
Recent reports in the literature, quoting records of the Choson Dynasty, indicate that the Kampo earthquake of 1741 (estimated magnitude M = 7.5), off the southwestern coast of Hokkaido, in the Sea of Japan, generated a destructive tsunami that was responsible for the death of about 1,500 people and that the waves affected the entire coast of Kangwondo, destroying houses and boats.
More recently, the earthquake of 1949 (M = 7.5) - known as the Kamuizaki-Oki Earthquake - and the Tsunami it generated were destructive. In the east coast of the Korean Peninsula, the tsunami waves ranged up to 2.0m at Uljin, Kyongsang-Pukdo, and the island of Ullung

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