Environmental Engineering Reference
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Fig. 10.12 The results of the maximum tsunami fl ow depths and affected ratios in Owase City.
Gray dots in ( a ) indicate locations of the observed fl ow depths from historical data
by the M 9 class earthquakes (which are less likely to occur). M 8 class earthquakes
in the southern part of Japan have an 88 % occurrence probability in Tokai (in the
next 30 years) and a 72 % in the Tonankai region (Earthquake Research Committee
2005 ). In this context, by referring to the defi nition of the tsunami inundation area
Level 1, the zone indicated by the red color in Fig. 10.12c should be considered a
Level 1 area and the area indicated by the yellow color Level 2. However, it should
be noted that the Level 1 area still has a 20 % ratio of being impacted by tsunamis
generated by M 9 class earthquakes, which amplifi es the risk in this area. Given the
existing conditions, therefore, the red-colored area should only be considered as the
tsunami inundation area Level 1 in terms of the affected ratio variable. In terms of
the hazard intensity, a range of tsunami fl ow depths generated by M 7 to M 9 class
earthquakes should be considered. In this context, the improvement of the structural
quality of buildings and other built environments in the Level 1 tsunami area may
be urgently needed. Nevertheless, public education and exercises, which are already
conducted in this city (e.g., Katada et al. 2006 ), should be continuously improved to
obtain a more effective and effi cient evacuation plan.
Although land use modifi cations and the construction of physical inland counter-
measures may be diffi cult in a populated city in a pre-disaster situation, the results
highlighted in this study may change if there are new countermeasures applied in
Owase City.
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