A Case of Utilizing Results

Technical support to designating the assumptions oftsunami inundation by preparing guidelines
SUWA Yoshio, HeadKATO Fuminori, Senior Researcher
Coast Division, River Department(Key words) tsunami inundation estimates, the creation of communities resistant to tsunami disasters,
the top class tsunami, tsunami inundation simulation
1. Outline
To support prefectural governors to designate theassumptions of tsunami inundation along the tsunami
prevention region development law, the Coast Division
prepared the guidelines on designating the assumptions oftsunami inundation in February 2012, and gave prefectures
technical advices, cooperatively with the Sea Coast Office ofthe Water and Disaster Management Bureau, Ministry ofLand, Infrastructure, Transport and Tourism. The guidelines
mainly introduce tsunami inundation simulations andmethods to use the results of the simulations.
2. Guidelines on designating the assumptions oftsunami inundation estimates
The assumptions of tsunami inundation present the areaand depth of inundation predicted by tsunami inundation
simulations for the top class tsunami.
The following are the major items in the guidelines.
・Designating the assumptions of tsunami inundation are aseries of setting the top class tsunami, setting calculation
conditions, simulating tsunami inundation, and outputting thearea and depth of inundation.
・The top class tsunami is set for each region’s coastline to be
the largest tsunami among the past tsunamis and theestimated tsunamis. Region’s coastline is dividing a coastal
region for shore protection basic plan into coherent coastlines
assumed the height of the tsunami is the same considering
natural conditions, past tsunami heights, and estimatedtsunami heights.
・Fault models that give the initial tsunami profile can be set
by referring reasonable models reviewed and published bypublic organizations such as the Central Disaster
Management Council and the Headquarter for theEarthquake Research Promotion.
・In tsunami inundation simulations for designating theassumptions of tsunami inundation, facility damage inducedby earthquakes and tsunamis should be considered that thetop class tsunami may occur in adverse conditions and cause
inundation from the viewpoint of protecting human life by allmeans, based on a lesson that there is no upper limit to thedisaster.
・To understand inundation induced by tsunami run up to theland, the largest area and depth of inundation etc. to be
designated in the assumptions of tsunami inundation are
output as the results of tsunami inundation simulations.
To solve issues grasped through works for the assumptions oftsunami inundation, the guidelines were revised three times(March, April, and October, 2012) to enrich explanations offacility conditions against earthquakes and tsunamis andothers.
3. Utilizing the guidelines
Together with preparing the guidelines, contact point fortechnical consultation on tsunami inundation simulations wasset up in the Coast Division, and explanatory meetings withprefectural officials and construction consultants were held inFebruary and March 2012. Besides these, to solve technicalproblems in designating the assumptions of tsunami
inundation, the Sea Coast Office of the headquarter and theCoast Division held opinion exchange meetings with officials
in prefectures and regional development bureaus in ten
regional blocks after April 2012, and responded to theconsultation of each prefecture. As of January 2013, Ibaraki,Aomori (only a part of coastlines), Tokushima, and Kochi
Prefectures have already designated the assumptions oftsunami inundation, and the other prefectures are supposed toproceed in works.
[Sources]
1) Guidelines on designating the assumptions of tsunami
inundation
http://www.mlit.go.jp/river/shishin_guideline/bousai/saigai/tsunami/shinsui_settei.pdf
2) The assumptions of tsunami inundation in Ibaraki
Prefecture
http://www.pref.ibaraki.jp/bukyoku/doboku/01class/class06/kaigan/tsunamisinnsui/l2shinsui.html
3) The assumptions of tsunami inundation in Aomori

Prefecture
http://www.pref.aomori.lg.jp/kotsu/build/tunami-sinsuisout
ei.html4) The assumptions of tsunami inundation in Tokushima

Prefecture
http://anshin.pref.tokushima.jp/docs/2012121000010/
5) The assumptions of tsunami inundation in Kochi

Prefecture
http://www.pref.kochi.lg.jp/soshiki/170201/tsunamimap.ht
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