Volcano Is a Volcano That the Scientific Community Thinks Will Never Erupt Again
The Kingdom of Tonga doesn't frequently attract global attending, but a trigger-happy eruption of an underwater volcano on January 15 has spread daze waves, quite literally, around half the world.
The volcano is commonly not much to look at. It consists of two small-scale uninhabited islands, Hunga-Ha'apai and Hunga-Tonga, poking well-nigh 100m above sea level 65km due north of Tonga'southward capital Nuku'alofa. Simply hiding below the waves is a massive volcano, effectually 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/xv hot jets of magma and steam exploded through the waves. Just these eruptions were pocket-size, dwarfed in scale by the January 2022 events.
Our research into these before eruptions suggests this is one of the massive explosions the volcano is capable of producing roughly every thousand years.
Why are the volcano'southward eruptions then highly explosive, given that bounding main water should absurd the magma downwards?
If magma rises into bounding main water slowly, even at temperatures of nigh 1200℃, a thin flick of steam forms between the magma and h2o. This provides a layer of insulation to allow the outer surface of the magma to cool.
Only this process doesn't work when magma is blasted out of the footing full of volcanic gas. When magma enters the h2o rapidly, any steam layers are quickly disrupted, bringing hot magma in direct contact with cold water.
Volcano researchers call this "fuel-coolant interaction" and information technology is akin to weapons-grade chemical explosions. Extremely fierce blasts tear the magma autonomously. A concatenation reaction begins, with new magma fragments exposing fresh hot interior surfaces to water, and the explosions echo, ultimately jetting out volcanic particles and causing blasts with supersonic speeds.
Baca juga: The 'pulse' of a volcano tin can be used to assistance predict its next eruption
Two scales of Hunga eruptions
The 2014/xv eruption created a volcanic cone, joining the ii old Hunga islands to create a combined island about 5km long. Nosotros visited in 2016, and discovered these historical eruptions were merely curtain raisers to the main event.
Mapping the sea flooring, we discovered a hidden "caldera" 150m below the waves.
The caldera is a crater-similar low around 5km across. Small eruptions (such every bit in 2009 and 2014/xv) occur mainly at the edge of the caldera, but very big ones come up from the caldera itself. These big eruptions are so large the meridian of the erupting magma collapses inward, deepening the caldera.
Looking at the chemical science of past eruptions, we now think the small eruptions represent the magma organization slowly recharging itself to fix for a big outcome.
We found evidence of two huge by eruptions from the Hunga caldera in deposits on the old islands. We matched these chemically to volcanic ash deposits on the largest inhabited island of Tongatapu, 65km away, and and then used radiocarbon dates to show that big caldera eruptions occur about ever yard years, with the last one at AD1100.
With this knowledge, the eruption on January 15 seems to be right on schedule for a "large ane".
Baca juga: Why White Island erupted and why there was no warning
What we can await to happen at present
Nosotros're still in the eye of this major eruptive sequence and many aspects remain unclear, partly considering the island is currently obscured by ash clouds.
The two earlier eruptions on December 20 2021 and January thirteen 2022 were of moderate size. They produced clouds of upward to 17km elevation and added new land to the 2014/15 combined island.
The latest eruption has stepped upwardly the scale in terms of violence. The ash plume is already about 20km loftier. Almost remarkably, information technology spread out almost concentrically over a distance of about 130km from the volcano, creating a plume with a 260km diameter, earlier information technology was distorted by the current of air.
This demonstrates a huge explosive power – one that cannot be explained by magma-water interaction alone. Information technology shows instead that big amounts of fresh, gas-charged magma have erupted from the caldera.
The eruption besides produced a tsunami throughout Tonga and neighbouring Fiji and Samoa. Shock waves traversed many thousands of kilometres, were seen from infinite, and recorded in New Zealand some 2000km away. Soon after the eruption started, the sky was blocked out on Tongatapu, with ash beginning to autumn.
All these signs suggest the large Hunga caldera has awoken. Tsunami are generated past coupled atmospheric and ocean shock waves during an explosions, simply they are besides readily acquired past submarine landslides and caldera collapses.
Information technology remains unclear if this is the climax of the eruption. Information technology represents a major magma pressure release, which may settle the system.
A alert, however, lies in geological deposits from the volcano's previous eruptions. These circuitous sequences testify each of the m-year major caldera eruption episodes involved many split up explosion events.
Hence we could be in for several weeks or even years of major volcanic unrest from the Hunga-Tonga-Hunga-Ha'apai volcano. For the sake of the people of Tonga I hope non.
Source: https://theconversation.com/why-the-volcanic-eruption-in-tonga-was-so-violent-and-what-to-expect-next-175035
0 Response to "Volcano Is a Volcano That the Scientific Community Thinks Will Never Erupt Again"
Post a Comment