Auckland's iconic landmarks Mount Eden, One Tree Hill, and Rangitoto are all evidence of the 360 km2 volcanic field that lies beneath our largest city. The field has erupted at least 53 times in the past 250,000 years, each time in a new location, resulting in many small hills and pits across the Auckland landscape. Volcanologists have been studying the magma source deep beneath the city to get clues to where the next eruption might occur. The chance of an eruption is very small but the consequences for residents would be large. GNS volcanologist Graham Leonard is co leader of the DEVORA programme which has been assessing the risk.