The Impact of the 2011 Tohoku Tsunami Disaster and Implications to Tsunami-resilient Community

Abstract

Abstract. Having passed more than three years since the 2011 Tohoku tsunami attacked the coastal communities, the devastated areas have moved forward to reconstruct their communities. Though the recovery processes are still underway, local municipalities completed the draft of reconstruction plan including infrastructure design, transportation, land use management, urban design, relocation, and economic and industrial outlooks. This study aims to summarize the impact of the 2011 Tohoku tsunami disaster, with particular regard to structural vulnerability, to understand the lessons towards reconstruction of Sendai city, Miyagi Prefecture. First, to identify the tsunami impact, the author’s team conducted an integrated study of field inspection, remote sensing and numerical modeling with the approach of spatial
information sciences. The findings lead to understandings of structural vulnerability with a form of tsunami fragility curve, i.e. the tsunami flow depth over 2 m will cause severe damage on houses and more than 6 m flow depth will cause total devastation, and to obtain an implication for land use management to reconstruct resilient coastal communities. Second,
we conducted the tsunami numerical modeling to evaluate Sendai city’s reconstruction plan with the concept of multiple protection which consists of the combination of structural prevention/mitigation, urban planning, preparedness, and suggest their land use management, relocation, housing reconstruction and tsunami disaster mitigation plans. We found that the multiple protections with 7-meter sea wall and 6-meter elevated prefectural road will contribute on substantial reduction of the tsunami inundation zone and flow depth on Sendai plain. Using this result, Sendai city determined the land used plan and the area of housing reconstruction and relocation.

Keywords: Tsunami, coastal, land use management