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.
The Hunga-Tonga-Hunga-Ha’apai submarine volcano erupted in mid-January with the power equivalent to hundreds of atomic bombs, causing a 15-meter high tsunami.
Three people were killed during this disaster which led to the destruction of homes and the breaking 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.
Mango Island in the Tonga archipelago before the volcano erupted. [Maxar Technologies – Keystone] Mango Island of the Tonga Archipelago after the volcano eruption. [Maxar Technologies – Keystone]
beyond the stratosphere
According to a study carried out by the New Zealand National Institute for Water and Atmospheric Research (NIWA), 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 in Indonesia, 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 an underwater volcano and that partly explains why there were tsunami waves too. important,” added Kevin Mackay.
huge plume
The team of scientists listed three quarters of the material projected during the eruption. The rest is 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 2000 km from Tonga.
His team also discovered that the volcano’s crater is now 700 meters deeper.
The pyroclastic flows, formed by volcanic projections reaching 1000 degrees 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.
>> NIWA New Zealand explanatory video on the volcanic eruption in Tonga:
ats/rad