Tsunami vulnerability of critical infrastructure : development and application of vulnerability models for impact assessment.

Abstract

As coastal populations continue to grow and develop globally, so does the exposure to the impact of tsunamis. Critical infrastructure provides services that underpin the everyday operation of society and is particularly important for post-disaster response and recovery efforts. Tsunamis can be highly damaging and disruptive to critical infrastructure, causing considerable consequences for impacted communities. With increasing development in coastal areas and associated expansion and reliance on complex critical infrastructure networks, tsunami risk assessments are becoming essential for informing disaster risk reduction initiatives. However, there are many challenges, particularly as this field is relatively new and has been dominated by tsunami hazard modelling. Tsunami vulnerability assessment has been comparatively understudied, especially the development of quantitative vulnerability models for critical infrastructure. Although there are documented observations of critical infrastructure impacts following previous tsunami events, vulnerability data tend to be mostly qualitative. There remains considerable opportunity to advance the tsunami risk assessment field by developing quantitative vulnerability models for critical infrastructure. This in turn can underpin robust risk-based information for tsunami risk management strategies and improve the resilience of critical infrastructure networks.

This thesis firstly reviews relevant policy, practice and academic literature to establish a theoretical and practical framing of tsunami risk assessment for critical infrastructure within the field of disaster risk reduction. It then presents quantitative empirical vulnerability assessments of tsunami impacts on critical infrastructure components, with a focus on transportation infrastructure. It does this by analysis of post- event tsunami field survey datasets, supported by remote sensing techniques, from the 2011 Tōhoku (Japan), the 2015 Illapel (Chile) and the 2018 Sulawesi (Indonesia) tsunami events. These vulnerability datasets are used to develop vulnerability curves, which are the first suite of empirical tsunami vulnerability models for critical infrastructure components. These vulnerability models broadly encapsulate a range of vulnerability factors including: tsunami depth, topography, distance inland (as proxy for energy deterioration), contraction scour, and asset type and design. These vulnerability models are then applied to a deterministic tsunami scenario case study in Christchurch, New Zealand, which models tsunami damage (roads and electricity), outage, and disruption and restoration time (roads). A collaborative engagement approach is taken, with local road and electricity network operators, to develop a framework for estimating tsunami damage and service disruption to network end-users affected by a large damaging tsunami in Christchurch. The overall contribution of the thesis is it provides the first public quantitative empirical vulnerability models for assessing tsunami impacts on infrastructure, and the first public tsunami impact assessment for infrastructure to consider direct tsunami damage with service outage, disruption and restoration time.