Probabilistic estimation of time required for disaster waste disposal generated by both ground motion and tsunami

Abstract

A catastrophic earthquake over Nankai Trough is predicted in the Pacific coastal region of Japan. The ground motion and giant tsunami caused by the anticipated Nankai Trough earthquake could cause significant damage to individual structures, resulting in serious deterioration of the functionality of the infrastructure in the community. As has been observed in past natural disasters, this earthquake would cause a large amount of disaster waste, which hider the post-disaster recovery processes in the affected areas. Disaster waste also has negative impacts on environmental and public health. Therefore, disaster waste management must be established in Japan to enhance the resilience of a community subjected to the anticipated Nankai Trough earthquake. Accurate estimation of the time required to dispose of disaster waste is critical in evaluating the resilience of a community and provides fundamental information for developing disaster waste management strategies.

This study presents a novel framework for the resilience assessment of disaster waste disposal systems with incineration facilities and bridge networks under both seismic and tsunami hazards. The resilience of disaster waste disposal systems is quantified as the risk associated with a residual amount of disaster waste conditioned upon the elapsed time from the earthquake occurrence. First, failure probabilities of buildings and bridges, and functionality deterioration of the road networks are evaluated based on seismic and tsunami hazards and structural vulnerability. In addition, the time-dependent disaster waste transportation and disposal are simulated based on the minimum-cost flow assumption and the principle of mass conservation considering the recovery process of the disposal system (e.g., capacities of incineration facilities given a time after the event). Finally, the resilience of disaster waste disposal systems can be estimated by Monte Carlo simulation considering uncertainties associated with estimations of hazards, vulnerability, and recovery activities of the systems. As an illustrative example, the proposed methodology is applied to a hypothetical disaster waste disposal system in Mie Prefecture, Japan, which would be subjected to both ground motion and tsunami caused by the anticipated Nankai Trough earthquake. The results demonstrate that the resilience of disaster waste disposal systems significantly depends on road network redundancy and locations of incineration facilities.