How to Cite

Kaida, H., & Kihara, N. (2020). FRAGILITY EVALUATION METHODOLOGY FOR TSUNAMI-BORNE DEBRIS IMPACT. Coastal Engineering Proceedings, (36v), currents.9.


In the safe design and risk assessment of structures in coastal area, it is important to consider tsunami-borne debris impact. Recently, probabilistic analysis has become the preferred form of analysis because of the large aleatory and epistemic uncertainties associated with tsunami effects, which are not captured in deterministic scenario-based assessments. By performing both a probabilistic tsunami hazard assessment (PTHA) and a tsunami fragility assessment (TFA) on structures, their annual failure frequency can be determined. The TFA involves evaluation of the response (e.g. debris impact force exerted on the structure) and the capacity of the structure to resist tsunami effects. Then, a fragility curve shows conditional damage probability of the structure for the tsunami magnitude (e.g., discrete tsunami height around the focused area). This study proposes a TFA methodology for tsunami-borne debris impact, as this has not yet been sufficiently established. Evaluation of the impact speed and impact probability of debris considering various uncertainties in the response evaluation are described in particular detail. Moreover, an assessment of a coastal industrial site was performed and fragility curves and the annual failure frequency of structures against debris impact were shown.

Recorded Presentation from the vICCE (YouTube Link):


Kihara, N., Kaida, H., Kimura, T., Fujii, D,, and Iizuka, K. (2018): Probabilistic tsunami hazard assessment (PTHA) and PTHA-based tsunami scenario at a Pacific coast of Tohoku, Coastal Engineering Proceedings, No.36.

Kihara, N., and Kaida, H. (2019): Applicability of tracking simulations of floating debris in tsunami inundation flow toward probabilistic assessment, Coastal Engineering Journal, Taylor & Francis, submitted.

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