The eruption of the volcano near Tonga in the past 15 of January put the entire planet on alert.
The volcano Hunga Tonga-Hunga Haʻapai, in the South Pacific, caused an explosion that was heard as far away as the United States, causing waves of more than one meter to hit the Tongan coast.
In its first statement on the damage, the government described the situation on Tuesday as an “unprecedented disaster” and reported three confirmed deaths, one of two locals (a woman from 65 years old and a man of 49) and a British citizen. This is Angela Glover, from 50 years old, who according to her family was trying to save her dogs when the water took her away.
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Communications in the area are paralyzed, after the eruption and tsunami cut an underwater cable, making it difficult to establish the scale of the destruction .
But the consequences were not only felt in the archipelago. TO 10.000 km from the volcano, in Peru, the death of two women was reported due to abnormally high waves high.
And in other countries, including Japan and Chile, they generated tsunami alerts.
What are submarine volcanoes like the one in Tonga like and how do they manage to unleash such powerful events?
What is a submarine volcano?
A submarine volcano is a volcano located wholly or mostly below sea level.
They form in places where magma from the interior of the Earth seeps through suckers or fissures of the earth’s crust on the sea floor.
Slide the button to observe the changes in the northern part of the main island of Tonga
Underwater volcanic eruptions are characteristic of rupture zones where the plates of the earth’s crust are formed, as explained by the US National Oceanic and Atmospheric Administration (NOAA).
In these areas of high seismic activity the magma rises and accumulates between the cracks in the rocks of the volcano, until there is no more space and it explodes.
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According to the NOAA, three quarters of the planet’s volcanic activity corresponds to submarine eruptions.
Some oceanographers estimate that there are a million volcanoes on the floor of the Pacific Ocean alone, according to the National Maritime Museum of the United Kingdom.
What is the Hunga Tonga-Hunga Ha’apai volcano like?
The volcano consists of the union of two uninhabited islands, Hunga Tonga and Hunga Ha’apai , located at 86 km north of Nuku’alofa, capital of Tonga.
This is an area of great seismic activity.
Protrudes 100 meters above sea level, but below it extends with a length of 1.549 meters and 20 km wide, as explained in an article by The Conversation volcanologist Shane Cronin, professor of Earth sciences at the University of Auckland, New Zealand.
In 2009, 2014 Y 2015 the volcano had magma and steam eruptions, but much smaller than the one in January 2022.
According to Cronin, this volcano is capable of producing eruptions as powerful as this every thousand years.
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The volcano is inside what is known as a “caldera”, which is a crater-shaped depression that gets deeper with each eruption.
How violent was the eruption?
The 8-minute eruption was so powerful that it could listening to more than 86 km away.
The column of smoke and ashes reached 20 km altitude and 65 km in diameter.
Cronin maintains that this was one of the strongest eruptions s of the last 14 years in the region of Tonga.
The Tonga volcano is of the basaltic type, like those of Hawaii or the Canary Islands, that is, its eruptions are not as violent compared to other types of volcanoes.
Basaltic eruptions are characterized by a spill of magma that flows.
“The difference is made by the contact of the magma with the seawater“, geologist Daniel tells BBC Mundo Melnick, a researcher at the Institute of Earth Sciences of the Austral University in Chile.
The expert refers to the fact that when the magma, which can be around 1.000℃, comes into sudden contact with the water, an extremely violent reaction occurs that fragments the magma.
This phenomenon is known as “fuel-refrigerant interaction”.
A chain reaction begins there, in which the new magma fragments come into contact with the water, generating new explosions that launch volcanic particles and detonations with supersonic speeds, as Cronin explains.
The volcanologist, however, indicates that the violent explosion cannot be explained solely by the interaction of the magma with the water.
According to him, “this explosion shows that large amounts of fresh magma, loaded with gas, erupted from the caldera.”
The expert mentions that by analyzing ash from eruptions previous and radio carbon techniques, has been able to establish that these eruptions in Hunga Tonga-Hunga Ha’apai occur every 1. 000 years.
The last one had occurred in the year 800, so “the eruption of the from January seems to be just within the time frame to be “great”, Cronin writes.
Melnick, for his part, warns that it is still too early to know how the dimension of this eruption compares with those of other recent eruptions of other volcanoes.
What caused the tsunami?
According to Melnick, there could be two main causes.
The first was the eruption itself . The expert refers to an “explosive bombardment” that pushes large amounts of water.
Y the second is that the eruption caused the collapse of the volcano’s caldera. With this, an underwater collapse is produced that also pushes the water.
“That is why after the eruption only a small piece of the island remained”, explains Melnick.
In any case, Melnick and other experts agree that more studies are still needed to understand better the causes of this tsunami.
What can be expected in the next few days?
“Right now the area of the eruption surely looks like Mordor,” says Melnick, referring to the hellish-looking country from the El Lord of the Rings.
The expert explains that the smoke and ashes that spread thickly through the air interact with each other and with the atmosphere, creating electrical storms and strong winds in the area.
It may take weeks before it returns to normal, says the expert.
It also holds maybe there’s more volcanic activity, “but there will not be an eruption like this, by no means”.
“What can happen is a new collapse because all the material is unstable, there can be an underwater collapse and generate another tsunami, but with more local effects in Tonga or Fiji”.
Cronin, for his part, adds that Although this was an event that released great magma pressure, it is not known if it was the climax of the eruption.
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expert indicates that other eruptions from the caldera of this volcano have included several separate explosions.
“We could be within weeks or even years of major volcanic upheaval from the Hunga-Tonga-Hunga-Ha’apai volcano,” says Cronin.
“For the good of the people of Tonga, I hope not”, concludes the volcanologist.
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