Probabilistic volcanic hazard and impact assessment for the Auckland Volcanic Field, Aotearoa New Zealand

Volcanic eruptions can be particularly complex events capable of producing multiple hazards simultaneously and/or consecutively, causing eruptions to have compounding impacts on society. Comprehensive volcanic risk assessments are, therefore, required to inform appropriate disaster risk and resilience strategies.

We present a conceptual framework for probabilistic volcanic multi-hazard impact assessments of societal elements. We develop this framework within a case study of the Auckland Volcanic Field (AVF), Aotearoa New Zealand, utilising existing eruption scenarios. This probabilistic approach will reduce the potential for bias that scenarios inevitably suffer from, and allow easier comparison with other similarly assessed risks (e.g. seismic).

We use existing dynamic eruption scenarios for the AVF, which include multiple volcanic hazards and transitions in eruptive style, for which we have relative likelihoods at every location in the field based on the matching of environmental factors and eruption styles. We combine these with detailed location-specific modelling of hazard phenomena to produce pseudo-probabilistic hazard and impact estimates. We anticipate producing results that can be interpreted as the site-specific probability of various hazard impacts, including combinations of hazard impacts arising from the entire suite of scenarios, weighted by likelihood of occurrence.

The results of this framework application should inform short- to long-term planning and mitigative strategies in Auckland, and for nationally significant sectors. The framework and case study will be incorporated as a module for broader national volcanic risk assessment and management frameworks.