Implementing RiskScape 2.0 for Tsunami Impact Assessment: A Case Study of Canterbury, Aotearoa New Zealand

Abstract

This study applies a risk assessment workflow through the RiskScape software to estimate direct damage and losses to buildings and roads from three damaging tsunami scenarios in the Canterbury region, Aotearoa New Zealand. The impact assessment case study (Canterbury) included three different tsunami hazard models: a 5 m wave height at the coast, a credible worst-case South-American-sourced tsunami and a credible worst-case Hikurangi-Trench-sourced tsunami.

The results of these impact assessments estimate that the total building loss from the 5 m, South American and Hikurangi Trench tsunami scenarios is >$500M (across ~6600 buildings), $3.5B (across ~28,600 buildings) and $2.1B (across ~18,500 buildings), respectively. The total length of tsunami-damaged roads for the 5 m, South American and Hikurangi Trench scenarios is estimated at 326, 654 and 588 km, respectively. The five most impacted areas, with respect to buildings (loss), are Sumner, South Brighton, Rawhiti, Moncks Bay and North Beach. The five most impacted areas, with respect to roads (total length damaged), are Styx, Ferrymead, Akaroa Harbour, Banks Peninsula Eastern Bays and Avondale. While tsunami impact-assessment methodologies are implemented to assess the tsunami impacts to buildings and roads, a proposed methodology is also provided for human casualty estimation to be implemented in RiskScape.

Key areas for future work include Aotearoa-New-Zealand-specific vulnerability models, implementation of casualty estimation models and all-infrastructure vulnerability models that consider service disruption and interdependencies.