A national-scale assessment of population and built-environment exposure in Tsunami evacuation zones

Abstract

Evacuation zones are a critical tool for mitigating loss of life in tsunami events. In New Zealand, tsunami evacuation zones are implemented by emergency management agencies at regional or sub-regional scales, providing national coverage for populated coastlines at risk to tsunami inundation. In this study, we apply the exposure component of a risk model framework (RiskScape) to deliver a first national-scale assessment of New Zealand’s population and built-environment exposure in tsunami evacuation zones. Usually-resident populations, buildings, land and transport network components are identified at an asset level and enumerated at national and regional scales. Evacuation zones are occupied by just under 10% of New Zealand’s population, residing in 399,000 residential buildings. These are supported by a further 5400 critical buildings and 6300 km of road transport network. Approximately 40% of exposed populations and buildings occupy evacuation zones expected to be inundated once every 500 years. This includes over 150,000 people in highly vulnerable age groups, i.e., children and elderly. The complex arrangement of built environments highlights a need for disaster risk managers to proactively identify and prepare populations for evacuation based on their vulnerability to harm from tsunami and ability to access resources for recovery after the event.