New Zealand is a geologically diverse group of islands on a plate boundary, resulting in beautiful views and high exposure to natural hazards including landslides. There have been over 1,500 recorded landslide-related fatalities in New Zealand (more than from earthquakes and tsunami combined) since 1760, and an economic impact of at least NZ $250–$300 M/year.
In January and February 2023, a series of severe storms triggered over 150,000 landslides, killed fifteen people (six in Auckland), and cost New Zealand over NZ$15 billion. Historically central and local government in New Zealand held a limited role in supporting homeowners after an event of this magnitude; typical involvement would be to manage imminent risk to life, while leaving private insurance to deal with remaining issues. However, in 2023 the New Zealand government recognised that the scale of the event required additional support, and saw an opportunity to reduce future risk by enabling a form of managed retreat. They developed a categorisation scheme for residential properties, which was implemented by local councils to classify properties by their risk level and remove people from intolerable risk.
This paper describes the scheme and its development, how it was implemented in Auckland, and some of the lessons learned that may be applicable to future scenarios of this scale.