<
https://theconversation.com/why-the-volcanic-eruption-in-tonga-was-so-violent-and-what-to-expect-next-175035>
"The Kingdom of Tonga doesn’t often attract global attention, but a violent
eruption of an underwater volcano on January 15 has spread shock waves, quite
literally, around half the world.
The volcano is usually not much to look at. It consists of two small
uninhabited islands, Hunga-Ha’apai and Hunga-Tonga, poking about 100m above sea
level 65km north of Tonga’s capital Nuku‘alofa. But hiding below the waves is a
massive volcano, around 1800m high and 20km wide.
The Hunga-Tonga-Hunga-Ha'apai volcano has erupted regularly over the past few
decades. During events in 2009 and 2014/15 hot jets of magma and steam exploded
through the waves. But these eruptions were small, dwarfed in scale by the
January 2022 events.
Our research into these earlier eruptions suggests this is one of the massive
explosions the volcano is capable of producing roughly every thousand years.
Why are the volcano’s eruptions so highly explosive, given that sea water
should cool the magma down?
If magma rises into sea water slowly, even at temperatures of about 1200℃, a
thin film of steam forms between the magma and water. This provides a layer of
insulation to allow the outer surface of the magma to cool.
But this process doesn’t work when magma is blasted out of the ground full of
volcanic gas. When magma enters the water rapidly, any steam layers are quickly
disrupted, bringing hot magma in direct contact with cold water.
Volcano researchers call this “fuel-coolant interaction” and it is akin to
weapons-grade chemical explosions. Extremely violent blasts tear the magma
apart. A chain reaction begins, with new magma fragments exposing fresh hot
interior surfaces to water, and the explosions repeat, ultimately jetting out
volcanic particles and causing blasts with supersonic speeds."
Via Christoph S.
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
