16:00 〜 18:00
[HDS08-P01] Risk evaluation of hypothermia caused by tsunami inundation due to large earthquakes around the world
キーワード：津波、低体温症、リスク評価
A large tsunami generated by the 2011 Tohoku great earthquake (Mw 9.0) caused a catastrophic disaster along the Pacific coast of northern Japan with about 16000 fatalities. The earthquake was occurred at 14:46 on March 11, 2011. The average and lowest temperatures during the 24 hours after the earthquake in Sanriku were 0.8 and -1.3°C, respectively. Furukawa, et. al., (2014) surveyed 134 patients who received medical care at the hospital within 72 hours after the earthquake in Miyagi prefecture. They showed that hypothermia caused by tsunami accounted for 76.3% (45/59) of all admissions, most patients arrived at the hospital within 24 hours. More than 80% of those patients were mild hypothermia or cold stressed (patients with core temperature 35-35.9℃) at initial stage, and 72.5% of those required hospitalization. They also showed that in-hospital mortality rate of hypothermia patients arriving at hospital within 72 hours was low (4.4%). However, Oshiro et al. (2022) indicated that hypothermic patients without vital signs (hypothermia stage IV) unlikely received emergency care or were transferred to a hospital because of triage in the catastrophic disaster. In this situation, the cause of cardiac arrest cannot be easily determined as drowning or hypothermia. Therefore, it was difficult to identify victims as candidates for extracorporeal life support, ECLS.
There are large cities along the Pacific coast in northern Japan, Hokkaido, where the temperature in January or February is always below zero. In those cities, a risk of hypothermia IV caused by a large tsunami inundation should be much higher than that for the 2011 Tohoku case. However, the situation should be improved when the response capabilities of the disaster area are large enough and when the medical staffs are well prepared. A wider range of victims can access medical resources, so victims with hypothermia IV can more likely receive medical treatment such as ECLS rewarming for arrested hypothermic patients. To prepare for saving a large number of victims with hypothermia, it is important to evaluate risks of tsunami hazards for hypothermia.
In this study, at first, monthly average minimum temperatures in the world provided by the climate view tool in the web site of Japan Meteorological Agency are used to identify places which had less than 0 ºC in the tables of 2020. The places along the coast of the Pacific and the Japan Sea are selected as candidates of vulnerable places for hypothermia due to tsunami. The places along the coast of Europe or the Atlantic are not selected because large tsunami disasters are only concerned along the coast of the Mediterranean Sea. Source areas of the historical giant earthquakes which occurred near those candidate places and generated large tsunamis (>10m) are selected. Then, large cities, with population of more than 50000, along the Pacific coast of Canada, Alaska, Kamchatka, and northern Japan, and also cities along the coast of Japan Sea including Japan, Russia and Korea are evaluated in terms of tsunami inundation risks.
The result suggested that 9 cities in Japan, Kushiro, Tomakomai, Hakodate, Hachinohe, Ishinomaki, Sendai, Akita, Sakata, and Niigata were identified as high-risk cities for hypothermia due to tsunami disasters. One city, Sokcho, in Korea is identified as a candidate, but a tsunami inundation risk is not evaluated previously. Therefore, we numerically computed tsunami inundation at Sokcho using the source of the 12th century earthquake occurred in southwestern Hokkaido, Japan (Ioki et al., 2019). The tsunami was propagated through Japan Sea and arrived at Sokcho about 2 hours after the earthquake. Tsunami was inundated in the populated area in Sokcho. Therefore, we found that Sokcho in Korea is also a high-risk city for hypothermia due to tsunami disasters.
There are large cities along the Pacific coast in northern Japan, Hokkaido, where the temperature in January or February is always below zero. In those cities, a risk of hypothermia IV caused by a large tsunami inundation should be much higher than that for the 2011 Tohoku case. However, the situation should be improved when the response capabilities of the disaster area are large enough and when the medical staffs are well prepared. A wider range of victims can access medical resources, so victims with hypothermia IV can more likely receive medical treatment such as ECLS rewarming for arrested hypothermic patients. To prepare for saving a large number of victims with hypothermia, it is important to evaluate risks of tsunami hazards for hypothermia.
In this study, at first, monthly average minimum temperatures in the world provided by the climate view tool in the web site of Japan Meteorological Agency are used to identify places which had less than 0 ºC in the tables of 2020. The places along the coast of the Pacific and the Japan Sea are selected as candidates of vulnerable places for hypothermia due to tsunami. The places along the coast of Europe or the Atlantic are not selected because large tsunami disasters are only concerned along the coast of the Mediterranean Sea. Source areas of the historical giant earthquakes which occurred near those candidate places and generated large tsunamis (>10m) are selected. Then, large cities, with population of more than 50000, along the Pacific coast of Canada, Alaska, Kamchatka, and northern Japan, and also cities along the coast of Japan Sea including Japan, Russia and Korea are evaluated in terms of tsunami inundation risks.
The result suggested that 9 cities in Japan, Kushiro, Tomakomai, Hakodate, Hachinohe, Ishinomaki, Sendai, Akita, Sakata, and Niigata were identified as high-risk cities for hypothermia due to tsunami disasters. One city, Sokcho, in Korea is identified as a candidate, but a tsunami inundation risk is not evaluated previously. Therefore, we numerically computed tsunami inundation at Sokcho using the source of the 12th century earthquake occurred in southwestern Hokkaido, Japan (Ioki et al., 2019). The tsunami was propagated through Japan Sea and arrived at Sokcho about 2 hours after the earthquake. Tsunami was inundated in the populated area in Sokcho. Therefore, we found that Sokcho in Korea is also a high-risk city for hypothermia due to tsunami disasters.