The DEVORA scenarios: multi-hazard eruption scenarios for the Auckland Volcanic Field

Abstract

Auckland is the most populous region in New Zealand with 1.6 million residents and accounts for over one third of New Zealand’s Gross Domestic Product (GDP). The Auckland metropolitan area is built upon the intraplate Auckland Volcanic Field (AVF), which poses a considerable threat due to the highly exposed people and infrastructure of Auckland. The Determining Volcanic Risk in Auckland (DEVORA) research programme was established in 2008 as a collaborative effort between GNS Science, numerous New Zealand based universities, and both local and central government agencies to improve volcanic hazard and risk management in Auckland. Since DEVORA’s inception, substantial advances have built on earlier research by using tools and approaches from geological, volcanic hazard, engineering, and societal risk disciplines. Volcanic eruption scenarios can integrate findings from each of these disciplines and produce outputs that benefit stakeholders. The ‘Mangere Bridge’ eruption scenario illustrated the impact an AVF eruption could have on Auckland’s urban functionality in a series of papers published in the Journal of Volcanology and Geothermal Research. However, this is but one scenario: the impacts of an AVF eruption could differ substantially depending on the specific area of Auckland that is affected by an eruption. The geologic record shows that eruption size, duration, style and sequence vary considerably within the AVF. Here, we build upon the Mangere Bridge eruption scenario and present seven new eruption scenarios that cover the spectrum of credible eruption phenomena expected from a future AVF eruption. The scenarios are based on research on AVF volcanic hazards and analogous eruptions from around the world. Our expectation is for the scenarios to be used within AVF volcanic impact and risk studies and to support volcanic risk mitigation and asset management practices.