Seventy-one municipalities in 10 prefectures, including Tokyo, on the Pacific coast could be hit by tsunamis that are at least 3 meters high within 30 years if a huge earthquake happens in the Nankai Trough (see below), according to estimated probabilities of tsunamis by the government's Earthquake Research Committee.
The tsunami probabilities on a regional basis, which were released Friday by the committee, shows that tsunamis that destroy wooden houses could reach 71 municipalities in 10 prefectures, including Shizuoka, Kochi and Wakayama, with an "extremely high" possibility of 26% or higher.
This is the first time that the government has presented tsunami probabilities. The committee has called on municipalities to use the estimates to strengthen their disaster prevention measures, while asking individuals to utilize the estimates to prepare for their evacuation.
The committee calculated the tsunami possibilities as of Jan. 1, 2020 with reference to magnitude-8 or 9-class earthquakes along the Nankai Trough that had happened once in about 100 or 200 years.
In 2012, the government released its estimates on the highest tsunamis in case of the Nankai Trough earthquake. But this time, it showed the degrees of urgency for tsunamis that have a high possibility of occurring.
According to the committee, it estimated about 350,000 patterns of tsunamis that could be caused by the Nankai Trough earthquake. Based on the estimates, it calculated probabilities of tsunami "at least 3 meters," "at least 5 meters" and "at least 10 meters" hitting 352 municipalities in 24 prefectures from Fukushima to Kagoshima within 30 years.
The committee announced the tsunami probabilities calculation results in three phases in the order of urgency -- "26% or higher" (extremely high), "6% or higher, but lower than 26%" (high) and "lower than 6%" (alarm needed).
The 26% possibility means that the event is expected to happen once in 100 years, while 6% means that the tsunami is expected to occur once in 500 years, the committee said.
As a result, the areas that could be hit by tsunamis that are at least 3 meters high with a possibility of 26% or higher would cover islets from Tokyo to Miyazaki Prefecture. They are a total of 71 municipalities in 10 prefectures, including all coastal cities, towns and villages in Kochi Prefecture. The areas that tsunamis at least 5 meters high could reach are 29 municipalities in seven prefectures.
The results of the calculation shows that the probabilities became higher in the areas of deeply indented coastlines.
-- Nankai Trough earthquake
An earthquake that is estimated to happen in 30 years with a probability of 70% to 80% in the areas along the Nankai Trough that stretches from Suruga Bay in Shizuoka Prefecture to the sea off Kyushu. According to estimates of damages reviewed in May 2019 by the government's Central Disaster Management Council, the number of deaths and missing persons if the quake occurs could be up to 231,000, while that of buildings destroyed or burned could be up to 2.094 million.
Read more from The Japan News at https://japannews.yomiuri.co.jp/
