The deadly volcanic eruption that hit the Tonga Islands earlier this year was the strongest on record with modern equipment, a New Zealand-led team of scientists revealed on Monday.
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The Hunga-Tonga-Hunga-Ha’apai submarine volcano erupted in mid-January with the power equivalent to hundreds of atomic bombs, causing a 15m high tsunami.
Three people were killed during this disaster which led to the destruction of homes and the rupture of the communications cable linking the archipelago to the Internet network. This small Pacific nation found itself cut off from the rest of the world for weeks, which complicated relief operations.
According to a study carried out by the New Zealand National Institute for Water and Atmospheric Research, almost 10 km3 of material were thrown, the equivalent of 2.6 million Olympic swimming pools. Debris was propelled to an altitude of more than 40 km, in the part of the atmosphere called mesosphere, beyond the stratosphere.
“The eruption has reached a record height, it’s the first we’ve seen cross the mesosphere,” said marine geologist Kevin Mackay.
The Hunga Tonga-Hunga Ha’apai eruption rivals the 1883 Krakatoa disaster that claimed tens of thousands of lives in Indonesia at a time when modern measuring devices did not exist.
“Although this eruption was significant – one of the largest since Krakatoa – the difference is that it is an underwater volcano and that partly explains why there were tsunami waves too. important,” Mr. Mackay added.
The team of scientists identified three-quarters of the material projected during the eruption, the rest being made up of debris dispersed in the atmosphere.
According to the geologist, the plume that rose above the volcano contained nearly 2 km3 of particles that remained in the atmosphere for “months, resulting in beautiful sunsets” that were even visible in New Zealand, more than 2,000 km from Tonga.
His team also found that the volcano’s crater is now 700m deeper.
The pyroclastic flows, formed by volcanic projections reaching 1000°C and a speed of 700 km/h, transported debris from the volcano to the seabed at least 80 km further.
“But the pyroclastic flows seem to extend beyond, perhaps up to 100 km,” said Emily Lane, the team’s research director.