Taupō supervolcano and caldera – Ōruanui eruption, 25,500 years ago

Our biggest volcano isn’t a cone, it’s a lake, formed about 25,500 years ago in the massive Ōruanui eruption shown in this video. The volcano spat out so much magma that the ground collapsed kilometres downward.

That huge hole – a caldera – now contains Lake Taupō.

The Pacific Plate plunges beneath the eastern North Island, 4cm every year. Pressure builds. Rock melts. Hot magma rises and feeds a long chain of volcanoes.

The Earth’s crust is unusually thin in the Taupō Volcanic Zone. Magma gets close to the surface – and sometimes breaks through. Every now and then, huge eruptions leave giant holes in the landscape.

A huge eruption here spat out so much magma that the ground collapsed kilometres downward and left a caldera – a gigantic collapsed block of land – in its wake.

Water filled the hole, and Lake Taupō was formed.

The volume of erupted material was 8–9 times the volume of water in Lake Taupō today.

Volcanic material filled the air. Most fell on the North Island, but some landed as far away as the Chatham Islands.

How much ash fell?
Ahuriri | Napier 2m
Tūranga-nui-a-Kiwa | Gisborne 1.2m
Whakatāne 1m
Te Papaioea | Palmerston North 50cm
Tauranga 40cm
Pōneke | Wellington 20cm
Rēkohu/Wharekauri | Chatham Islands 18cm
Ngāmotu | New Plymouth 15cm

Still active – After an eruption in the central North Island, volcanic ash could cover the entire island and beyond.

Since Ōruanui, there’ve been 28 smaller eruptions of Taupō. No super eruption will happen in your lifetime – the magma takes too long to build.

Thanks to monitoring by GNS Science, we can expect some warning before the next one.

Taupō is a global star – the world’s most active supervolcano. It’s studied by scientists everywhere.


Credit:
Reference landscape image courtesy of LINZ. CC BY 4.0, Rūaumoko illustration by Ben Te Aika

Read more about the Taupō caldera on our website: https://tepapa.nz/caldera