Auckland, New Zealand is the economic hub and the most populous city in New Zealand. Problematically, it is also built on the monogenetic Auckland Volcanic Field (AVF), meaning a future volcanic eruption is possible anywhere within the 360 km2 areal extent. When compared to other perils (e.g. earthquakes, floods, and hurricanes), volcanic impact and risk assessments are poorly developed. This is primarily due to volcanic eruptions having the potential to last for long durations with multiple interacting hazards occurring during an eruption sequence. To explore the consequences of an AVF eruption, we developed the ‘Mt Rūaumoko’ geophysical scenario lasting one month in duration to evaluate impacts and restoration time for various critical infrastructure sectors. To describe and quantify the impact of “Mt Rūaumoko” to Auckland’s infrastructure, we applied vulnerability models developed from 20 years of New Zealand-led volcanic impact reconnaissance trips, historical volcanic impact documentation and controlled laboratory testing. Importantly, we met with over 20 Auckland Lifelines Group members (a voluntary group of infrastructure providers in Auckland) who have a profound knowledge of Auckland’s infrastructure networks, systems requirements, and capabilities to check our level of service estimates for the entirety of the scenario. We present rail as an example of the work carried out for all infrastructure sectors. Our study is the most comprehensive consideration to date of the societal consequences of an AVF eruption and highlights the wide-ranging and surprising impacts such an event could impose on New Zealand’s largest city. Our findings will be used as a case study for the economic modelling, which will inform public policy on choices for new infrastructure resilience investments.