Probabilistic Assessment of Seaport Disruptions under Tsunami Events

Seaports are critical coastal infrastructures whose disruption during tsunami events can trigger major economic losses and cascading impacts across global supply chains, including indirect effects on ports that are not directly impacted but are operationally and logistically linked to affected ports through inter-port dependencies. Existing approaches to assessing their operational vulnerability often fail to simultaneously capture both component-level and system-level effects, as well as the inherent uncertainties in port operations. This study presents a comprehensive framework using a Bayesian network (BN) to assess disruption at affected ports and the resulting indirect business loss at other ports under varying tsunami intensities. The proposed approach considers offshore wave height and amplification to derive the probability distribution of inundation depth as the primary hazard intensity measure, which is then propagated through interconnected port subsystems and port-to-port dependencies to enable probabilistic inference of both direct and indirect disruptions. The 2011 Great East Japan Tsunami is used as a case study to assess port disruptions in the Tohoku region and the associated indirect impacts on other ports. Our preliminary results indicate that a tsunami inundation depth of 2.0-4.0 m leads to significant operational impacts, with a 55% probability of port disruption exceeding 90 days and a cumulative 84% probability of the disruption lasting at least 50 days. Stress testing is also employed to evaluate how port functionalities respond under a spectrum of tsunami scenarios. This probabilistic approach provides port authorities and coastal planners with a decision-support tool to evaluate potential direct and indirect disruptions and optimize recovery strategies, thereby enhancing maritime infrastructure resilience against future tsunami hazards.