Éruption du volcan des Tonga

Tonga eruption equals ‘hundreds of Hiroshima bombs’, NASA says

On January 15, a volcano in the kingdom of Tonga, which is located in the South Pacific, exploded with a power the Earth has not seen in the past 30 years. NASA scientists estimated that the explosion had a power exceeding that of 100 “Hiroshima bombs”.

To get an idea of ​​the power of the eruption, scientists combined satellite data and surface data about the volcano. They also considered the amount of rock displaced during the explosion, the apparent height of the eruption cloud, and many other parameters.

However, the researchers said this is still a preliminary estimate. According to Jim Garvin, chief scientist at NASA’s Goddard Space Flight Center, the amount of energy released by the eruption was between 4 and 18 megatons of TNT. For information, a megaton is the equivalent of a million tons.

More powerful than a nuclear bomb

The uninhabited island of Hunga Tonga-Hunga Ha’apai formed the highest part of a massive underwater volcano. The island rose to a height of 1.8 kilometers from the seabed and had a diameter of 20 kilometers. The volcano began experiencing small eruptions towards the end of December 2021 before erupting violently a few weeks later.

The researchers compared the power of the volcanic eruption with the nuclear bomb that the United States dropped in August 1945 in Hiroshima, Japan. If this atomic bomb had, at the time, exploded with 15 kilotons of energy, the eruption of Tonga would, according to them, be a hundred times more powerful. It would be the most powerful volcanic eruption recorded since Mount Pinatubo in 1991.

An “ultra Surtseyan” eruption

Since 2015, Garvin and his colleagues have been closely monitoring the volcano in Tonga. At the time, the volcano’s magma was creating new land above the surface of the water, which connected the islands of Hunga Tonga and Hunga Ha’apai.

According to Garvin’s explanations, it is common for eruptions to appear on volcanoes like that of Tonga, in particular because of the contact of liquid water with high-temperature magma. This contact produces violent steam explosions called “Surtseyan eruptions”.

Garvin said the January 15 eruption was much more violent than a typical Surtseyan eruption. He thinks the cause could be the large amount of water involved in the phenomenon.

Because of the uniqueness of the Tonga eruption, Garvin and his fellow volcanologists decided to informally call it an “ultra Surtseyan” eruption.

SOURCE: Livescience

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