The deadly volcanic eruption that hit Tonga earlier this year was the strongest ever recorded with modern equipment, a New Zealand-led team of scientists revealed on Monday.
The underwater volcano Hunga-Tonga-Hunga-Ha’apai exploded in mid-January with the equivalent power of hundreds of atomic bombs, causing a 15-meter-high tsunami.
Three people died during this disaster which led to the destruction of homes and the breaking of the communication cable that connects the archipelago to the Internet. This small Pacific nation has been cut off from the rest of the world for weeks, complicating rescue operations.
beyond the stratosphere
According to a study by the New Zealand National Institute for Water and Atmospheric Research, almost 10 km3 of material were thrown away, the equivalent of 2.6 million Olympic swimming pools. The debris was blown up to an altitude of more than 40 km, in the part of the atmosphere called the mesosphere, beyond the stratosphere.
“The eruption reached a record height, it’s the first we’ve seen to cross the mesosphere,” said marine geologist Kevin Mackay.
The Hunga Tonga-Hunga Ha’apai eruption rivals Indonesia’s 1883 Krakatoa disaster, which claimed tens of thousands of lives 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 a submarine volcano and that partly explains why there were also major tsunami waves,” Mackay added.
The team of scientists listed three-quarters of the material spewed out during the eruption. The rest is airborne debris.
According to the geologist, the plume that rose above the volcano contained almost 2 km3 of particles that remained in the atmosphere for “months, giving rise to stupendous sunsets” visible even in New Zealand, more than 2000 km from Tonga.
His team also found that the volcano’s crater is now 700 meters deeper.
The pyroclastic flows, formed by volcanic projections reaching 1000°C and speeds of 700 km/h, carried debris from the volcano to the seabed at least 80 km further on. “But the pyroclastic flows appear to extend beyond that, perhaps as far as 100km,” said Emily Lane, research director on the team.