This endowed research division is established based on the agreement between Tohoku University and Tokio Marine & Nichido co., ltd for collaborative research on earthquake and tsunami risk evaluation in 2012. The objective of the collaboration is to apply advance knowledge and data on disaster science to improve the understanding on earthquake and tsunami risk assessment in terms of insurance business and develop and strengthen human resources for both sides. The collaborative research results will be contributed to public such as academic research papers and symposiums.
As of 2014, several results from the three main researches have been developed by this division namely tsunami hazard assessment using fragility functions, tsunami evacuation, and disaster mitigation education.
The classical method for tsunami hazard assessment is enhanced using the stochastic method to quantitatively estimate the probable maximum tsunami height along the Japanese coast with the consideration of uncertainty. In addition, tsunami hazard maps for different earthquake return periods are also proposed as one option to quantify the tsunami risk. High accuracy of tsunami fragility functions are developed using detailed building damage data in the case of the 2011 Great East Japan tsunami in Ishinomaki city and Kesennuma city and applied with the advanced statistical method in earthquake engineering field. In addition, data of damaged fishing boats are also analyzed to first developed the fragility functions for fishing boat by taking into account the tsunami flow velocity, floating debris and other impact. (Fig. 1 and 2)
Fig.1: Inundation map for each return period based on probabilistic tsunami hazard analysis
Fig.2: Fragility surfaces representing the probability of reaching or exceeding “collapse” for the affected wooden buildings in Kesennuma, during the 2011 Great East Japan Tsunami with and without considering impact from floating debris (Upper and lower figures). Individual points represent the expected probability for each individual building, given the tsunami flow depth, and velocity.
In terms of tsunami evacuation, this division supports tsunami evacuation drills in Miyagi prefecture with the closed collaborative work with local governments to develop tsunami evacuation plans and drills. These works are scientifically evaluated such as utilizing questionnaires to understand tsunami evacuation behavior and to obtain statistical data for each evacuation drill event. This evacuation project referred to as `Kakeagare Japan`, is a collaboration which includes counterparts outside of IRIDeS which acts as a model for tsunami evacuation drill to be developed not only in Japan, but in other countries such as in Phuket, Thailand (Fig. 3).
Fig.3: Tsunami evacuation drill utilizing the evacuation stairs along the Sendai-Tobu expressway
For activities related to disaster mitigation education, special classes were held in both many tsunami affected schools in Miyagi prefecture and beyond such as in Izu-Oshima Island in Tokyo. Classes were also organized in the state of Hawaii, USA and Bangkok and Phuket, Thailand (Fig. 4).
Fig.4 Upper-left: Disaster mitigation program in Phuket, Thailand
Upper-right: Disaster mitigation program in Miyagi, Japan
Lower-left: Disaster mitigation program in Hawaii, United States
Lower-right: Tsunami evacuation drill for students in Phuket, Thailand
In the future, this division plans to continue and strengthen our research especially on earthquake induced tsunami risk assessment and other related activities.