Volcanic city

Auckland, New Zealand, is built on top of more than fifty volcanoes.

Auckland from Maungawhau / Mount Eden
Etherbug, Alan Collins, CC BY 3.0, via Wikimedia Commons

Humans have a love/hate relationship with volcanoes. On the one hand, volcanic soils are some of the most fecund on Earth, and most volcanoes almost never explode while we’re on top of them. On the other hand, sometimes they do.

Several cities around the world are built very close to volcanoes: Seattle, Naples, Batangas, Goma… but Auckland, the largest city in New Zealand, is the one that takes the cake. Auckland is built not just next to a volcanic field, but directly on top of it. Underneath this city of one and half million people lie more than fifty volcanoes.

If you look at any map of Auckland, you will see dozens of park-like outcroppings, little hills in the midst of the suburbs:

Epsom, Auckland
Prosperosity, CC BY-SA 4.0, via Wikimedia Commons

These hills are extinct volcanoes. Some are scoria cones, others are tuff rings, and others have blown out completely, leaving only craters. The entirety of the city is built on a volcanic field that is dormant, but not extinct:

Auckland volcanic field
Ferdinand von Hochstetter (1829-1884), Public domain, via Wikimedia Commons

The first eruption was about 200,000 years ago in Pupuke. (Incidentally, I live only a few minutes away from Pupuke. It’s a nice place to take the kids.) The latest eruption – just six hundred years ago – formed the spectacular Rangitoto Island. That was recent enough to have been seen by the Māori inhabitants of the area; nevertheless they and later European settlers stayed and built New Zealand’s largest city.

Because of the nature of the volcanic field, most of these volcanoes are unlikely to erupt again. Instead, the magma bubbling away under the surface will probably create an all-new volcano at some point in the future. Where and when is impossible to predict.

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