It’s new, it’s exciting, and while it kind of sounds like a dance move, the Tangaroan style is in fact the newly classified third type of eruption style. We’ve got eruptive and effusive and now this.
It was classified by a team of researchers from the National Oceanography Centre (Southampton, UK) and Victoria University (Wellington, New Zealand) who studied Macauley volcano in the south west Pacific.
The news appeared in this month’s edition of Nature Geoscience. The paper is called ‘Highly vesicular pumice generated by buoyant detachment of magma in subaqueous volcanism‘.
So what’s the deal?
Well, the Tangaroan style is specifically an underwater eruptive style. If it had happened subaerially it would be intermediate – somewhere between effusive and eruptive. And the main defining feature of this style is its foaminess. See, lots of vesicles form in the magma, and as it bubbles up it turns into a kind of foam, which detaches as packets of pumice and rises. Because of the effects of decreasing water pressure, the bubbles continue expanding so you end up with various sized bubbles by the end of it.
Pumice (which is usually a sign of explosive activity in subaerial volcanoes) is quite common in underwater volcanoes, and this new research means that underwater volcanoes currently marked as having explosive eruptions in the past may be reassessed under this new category. Exciting stuff!
The style is called Tangaroan after the Maori god of the sea, but it also acts as a homage to the ship used to collect samples, which shares the name. Fun fact: Tangaroa is also part of the Cook Islands’ mythos and has yellow hair, so when Europeans first visited, they were considered the children of Tangaroa.