Hokkaido Nansei-Oki Tsunami, July 12, 1993
A large 70-m long barge was moved 75 m from the harbor by the flooding tsunami waves. The crane on the barge is used to lift concrete units from the nearby fabricating area to breakwaters and protective bulkheads surrounding the harbor area.
An earthquake occurred off the west coast of Hokkaido and the small offshore island of Okushiri in the Sea of Japan. In two to five minutes the tsunami, one of the largest in Japan's history, engulfed the coastline of Okushiri Island and the central west coast of Hokkaido. Almost two hundred fatalities were associated with the event, with more than half attributed to the tsunami. The $600 million in property losses were attributed primarily to the tsunami. This tsunami caused spectacular localized damage, especially on the southwestern shores of Hokkaido and on Okushiri Island. This slide set shows damage to ships, dwellings, and businesses, and unique views of clocks stopped in time by the tsunami.On July 12, 1993, at 22:17 local time (13:17 GMT), a magnitude 7.8 earthquake occurred off the west coast of Hokkaido and the small offshore island of Okushiri in the Sea of Japan (42' 47'N, 139' 12'W). In two to five minutes the tsunami engulfed the coastline of Okushiri Island and the central west coast of Hokkaido. Almost two hundred fatalities were associated with the event, with more than half attributed to the tsunami. The death toll on Okushiri Island was 165. The $600 million in property losses were attributed primarily to the tsunami. This 1993 earthquake filled a previously identified seismic gap. This tsunami caused spectacular localized damage, especially on the southwestern shores of Hokkaido and on Okushiri Island.West Coast of Okushiri Island: This area experienced the highest runup measurements. All twelve houses in the village of Monai were destroyed, killing 10 persons. Runup measurements around the village were 20 m and in a small valley north of Monai on the southwest coast the runup was measured at 31 m, the maximum for this event. South of Monai, tsunami runups along the coast ranged from 15 to 20 m. Vegetation was stripped off the hillside, and large boulders up to one-meter in diameter were deposited on the flooded vegetation. These data suggest that the initial wave arrived from west of Okushiri Island.Southern Coast of Okushiri Island: The tsunami was refracted by the shoaling bathymetry at both ends of the island. The town of Aonae (population 1,600) at the southern tip of Okushiri was hardest hit.About four to five minutes after the main earthquake shock, the first tsunami wave arrived, flooding the southern tip of the island and the entire first row of houses nearest the coast. Two fires started on the damaged fishing vessels after this first wave. The tsunami appeared to arrive from the northeast, with flooding of between three and seven meters throughout the town.About seven minutes after the first wave, a second, larger wave hit from the east carrying the burning boats into the main town. The second wave advanced further ashore than the first and completely flooded the first three rows of houses with a runup of between five and ten meters throughout the town.The combination of a strong, northeast wind, the burning boats, and an ample supply of heating propane and kerosene spread the fire quickly and destroyed 340 homes. However, only two of the 114 deaths in Aonae were caused by fire. The houses in the central part of Aonae were flooded by tsunami waves that ran up to a height of five meters. Further from the shore the structures were destroyed by fire. The tsunami destroyed a portion of the sea wall, and fishing boats were left "high and dry" in the inundation zone.Northern and Eastern Coasts of Okushiri: At Inaho, on the northern point of Okushiri Island, 13 people were killed and all houses were destroyed by the 10-m waves. The eastern side of Okushiri Island appeared to be sheltered from the waves, and the measured tsunami runup was between two and five meters.Hokkaido: Severe damage was caused by the earthquake and accompanying fires, landslides, and the tsunami on southwestern Hokkaido-540 houses were destroyed and 1,834 others were damaged. The tsunami also hit the Island of Hokkaido, arriving at Ota Bay within five minutes of the main shock and destroying five homes. Runup in this area was nine meters. Damage also occurred at Setana from the six meter waves. The coastline from Suttsu to south of Ota Bay was hardest hit with runup values of five to nine meters. Outside this area, the tsunami intensity tapered off rapidly, and runup values were below five meters.Other Areas: After 90 minutes, the tsunami struck the coast of the Republic of Korea, where a maximum tsunami runup of two meters was recorded. One person on a fishing boat was killed near Aomori, Honshu. A runup of nearly one meter was recorded there. Three people from the southeast coast of Russia were missing after the tsunami. The tsunami affected much of the southeastern coast of Russia and also caused damage to a factory at Kamenka, Sakhalin Island.The tsunami traveled to Russia within 30 minutes, causing runups of one to four meters. Damage estimates were over $6 million (U.S. Dollars). Approximately 700 fishing boats were damaged or lost off western Japan, southeastern Russia, the Republic of Korea, and the Democratic People's Republic of Korea.
Metadata Last Modified: 2011-04-06
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