A Volcano Erupts In Auckland.... In Theory

Lava, super-heated gas and ash clouds pour over New Zealand’s largest city, displacing many thousands of residents, and destroying an area 5 km in diameter. A doomsday scenario? Certainly. But it’s one that scientists at GNS Science , the University of Canterbury , and
Massey University have investigated, in the hope that if such an event came, Auckland’s infrastructure and services would be ready.
Their findings appear in the latest issue of the
Journal of Volcanology and Geothermal Research ($) . The authors describe this paper as the first in a series that will use “…a credible scenario of evolving volcanic activity in an urban center to explore both urban evacuation implications and the consequences…on critical services.” This includes an analysis of the physical damage wrought by the eruption and the related earthquakes, as well as the by-products, such as ash. As the eruption of an unpronounceable Icelandic volcano in 2010 showed, volcanic ash can effectively shut down the airspace of entire countries. And like the gases emitted during an eruption, ash can also pose a significant health hazard to those in the affected area, as well as having an impact on agricultural areas, important in food production.
Before we look at the scenario in detail, if you’ve been to the city, and find yourself wondering where Auckland’s volcano is, the answer is: pretty much everywhere. The entire city sits on what’s called a monogenetic volcano field – a vast area of many small, singly-erupting volcanic vents – so it doesn’t look like the traditional pointy volcano. Rather, its existence is the result of magma oozing from various pores at various locations, at different points throughout history.
Auckland’s volcano field covers an area measuring 360 km 2 , and includes more than 50 vents. Volcanoes have erupted in the field more than 55 times in the past 190,000 years, producing a cumulative volume of ~2 km 3 of volcanic deposits. However, all this has happened without any obvious pattern. In fact, the oldest vent, called Pupuke, and the youngest, Rangitoto [Island], are located next to each other. The researchers say that the field “will almost certainly erupt again,” but that the size of the next eruption is difficult to forecast. In addition, the lack of existing pattern means that “it is very likely that the next vent will erupt in a new location within the field.” Information that’s unlikely to comfort the ~1.4 million people living there.
THIS IS NOT AUCKLAND... but this aerial view shows lava spouting out of the Piton de la Fournaise volcano on February 1, 2017, on the French island of La Reunion in the Indian Ocean. (Image credit: RICHARD BOUHET/AFP/Getty Images)