Tonga Volcano Eruption: This is what we know so far

by time news

Satellite images of the Tonga volcano showcase the huge eruption column, and the volcanic transformation that covered large parts of the country. The photos of Honga-Tonga-Honga-Apaai are indeed impressive, but as of today, they are the bulk of the documentation in our possession to try and understand what happened there.

Yesterday (Sunday), with the eyes of the world still married to the capital Nuku’alofa, a huge cloud of volcanic ash continued to cover the entire region. The surveillance flights sent from New Zealand to estimate the extent of the damage had to be returned empty-handed. In contrast, the impact of the eruption on the ocean was quite clear, and was felt in the form of waves of about half a meter to 80 cm, not only in the island state of Tonga, but also in Peru and the west coast of the United States.

Photo: AP

Today, after some clearing of the sky, New Zealand and Australia were able to send military surveillance flights again. These will assess the damage from the eruption and tsunami that came immediately after it. New Zealand hopes to later also deliver supplies of essential products, including drinking water, that desperate Tonga residents desperately need. Significant damage to property has already been recorded, but fortunately no casualties or casualties have been reported, except for a British citizen who is still defined as missing. Meanwhile, the lines of communication with the kingdom remain rather limited; The only company that operates the submarine fiber optic network, the one that connects Tonga to the rest of the world, explains that repairing the damage caused to the cables will probably take weeks.

What do we know so far?

Honga-Tonga-Honga-Apai is an underwater volcano, which usually erupts underwater. It is estimated that there are hundreds of thousands of underwater volcanoes. They, like terrestrial volcanoes, are located near the tectonic plate connections, where they form. According to the International Ocean Research Foundation about three-quarters of all volcanic activity on Earth occurs underwater. The Tonga Volcano, about 65 km from the capital, has a history of eruptions. Ash to a height of about 17 km. Which even led to the formation of a small island. On December 20, and again on January 13, the Tonga volcano erupted again, the ash cloud was seen from one of the islands in the kingdom.

Volcano eruption on Tonga Island (Photo: News)
Photo: News

The last eruption on Saturday was more significant than what we were used to seeing there, with an eruption column rising to a height of 20 km (a few hundred meters to a few kilometers, as usually happens). The height of the tsunami wave hitting the shoreline was about 80 centimeters. Dr Robin George Andrews, a British volcanologist who has written extensively on the subject, says that an eruption of this magnitude when it comes to underwater volcanic mountains is quite rare, and occurs once every 1,000 years. “It’s the amount of time it takes him to ‘fully charge.’

What caused the tsunami waves?

Submarine volcanic eruptions can lead to a tsunami, a series of ocean waves caused by the displacement of large amounts of water. The more headwinds and trends – the greater the potential for a tsunami – also increases. However, the process is not yet agreed upon by scientists, and there is a debate on this issue. Even in the case of the Tonga eruption on Saturday, especially when the details have not yet been fully clarified, it is not clear what exactly caused the tsunami. It could be that it was part of the volcano that collapsed in the ocean and caused the huge movement, or it was actually the explosion that took place underwater, or maybe both.

Tsunami hits Tonga Island (Photo: News)
Photo: News

Not just a tsunami and dirt

The supersonic boom was absorbed by measurements made in Alaska and England, notes Prof. Yishai Weinstein of the Department of Geography and Environment at Bar-Ilan University, and it is estimated that this is one of the most powerful explosions in the 21st century to date.

Prof. Weinstein explains that according to these signs, it is very possible that the caldera of Honga, a depression of a mighty explosion of an ancient volcano, was involved in the eruption in question. In fact, “I have no reason to think it will end in this eruption. Outbreaks of this kind usually do not end in a few hours.” Weinstein explains that most of the time in eruptions in submarine volcanoes like the one in Tonga, only part of the trend and pressure that is building up in the underground reservoir is released. In contact with water, at temperatures above 1,000 ° C, a relatively moderate reaction occurs between the water and the trend; The water cools the trend, steam is formed from the tray between them, which is what accompanies the eruption.

Prof. Yishai Weinstein, Bar Ilan University (Photo: Private Photography)
Prof. Yishai Weinstein, Bar Ilan University | Photography: Private photography

It usually occurs at shallow depths, and amounts to a medium-sized eruption. This time, the picture is as stated different, grandiose and more turbulent than usual. The heavy, ancient bottom of the Pacific Ocean descends beneath the surrounding bottoms. These connecting lines, the fragments in the ground, are called replicas. Displacement of the bottom in replicas confirms a situation where water penetrating inside allows the basalt rock inside to lower its melting temperature. More and more trend is sinking to depths, over the years, and in combination with volcanic gas – more and more pressure is being built. Thus, Prof. Weinstein explains, it probably happened in Tonga, which led to the powerful eruption on Saturday.

Hundreds of lightning bolts per second

“As a volcanologist,” says Prof. Weinstein, “the understanding that there are still quite a few missing in this story is disturbing, and of course we will continue to examine what is happening there in the coming weeks and months, and the picture is likely to become clearer.” Another fascinating phenomenon that Weinstein points out is the accumulation of lightning that appeared in the area and was visible in the distance. “Lightning is a characteristic of powerful eruptions, those that involve throwing dirt into the air, as indeed happened in this case. It happens because of the collisions of those particles in the air, combined with the ice particles in the atmosphere.

This process produces electric charges, the negative ones are separated from the positive ones and this is how the flash is created, “explains Weinstein. Once recorded. 340,000 lightning strikes recorded over an entire week in 2018, in the eruption of the Anak Krakata volcano in Indonesia, pale in front of the 200,000 lightning strikes in just one hour absorbed in the Tonga eruption. “What is the exact explanation for this huge amount? We still do not know. “

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