Presentation Information
[O12-P28]Consideration of Tsunami Inundation Hazard Maps Incorporating Flow Contraction Effects from the Perspective of Urban Tsunami Damage
*Yuki HIKICHI1, *Aoi HAMADA1, Kosuke KATO1 (1. Miyagi Prefecture Tagajo High School)
Keywords:
urban tsunami,flow contraction,hazard map
An urban tsunami occurred in Tagajo City, Miyagi Prefecture, during the Great East Japan Earthquake. Interviews with the city officials revealed that the hazard maps did not incorporate the effect of flow contraction, which causes water levels to rise in densely built-up areas. Therefore, the objective of this study is to evaluate the necessity of incorporating flow contraction effects into tsunami hazard maps. First, a comparison of the actual tsunami inundation area with the projected area showed no significant difference, likely because the hazard maps were based on the maximum assumed damage. Next, tsunami inundation simulations revealed that the maximum inundation depth was higher with flow contraction in coastal areas, whereas it was higher without it in inland areas. This suggests that while flow contraction increases inundation depth in certain areas, it does not necessarily expand the overall inundation range. This is because the dense concentration of buildings in inland areas also creates a resistance effect similar to a seawall.