Eruption of the Hunga Tonga volcano | An explosion “of rare violence”

The eruption of the Hunga Tonga volcano on January 15 is already considered one of the most important of the XXI^and century, and can be studied by experts for years. Explanations.

Nicolas Berube
The Press

Like hundreds of Hiroshima

According to NASA, the eruption of the Hunga Tonga volcano released around 10 megatons of energy, or as much as a few hundred bombs like the one that destroyed Hiroshima. Fiona Ann Darbyshire, professor in the Department of Earth and Atmospheric Sciences at the University of Quebec in Montreal (UQAM), notes that “significant quantities of material were projected, and the shock wave of the he eruption crossed the entire globe several times. We are talking about a super-powerful explosion”. More than 100,000 people in Tonga have been cut off from communications. The magnitude of the cloud is comparable to the eruption of Pinatubo in the Philippines in 1991, according to NASA.

Distance Montreal-Rimouski

An hour after the explosion, the cloud of debris and dust reached a width of 640 km. That’s more than the distance between Montreal and Rimouski! The ash cloud was propelled into the stratosphere, about 50 km from the ground.

Many hours

Satellite images broadcast on the Net showed a rapid and gigantic explosion, but they were greatly accelerated to illustrate the event. In fact, the explosion took place at 5:10 p.m. local time. Quickly, the ash cloud reached a width of 38 km. Half an hour later, at 5:40 p.m., the cloud was 340 km wide, or about the distance Montreal-Montmagny. An hour after the eruption, the cloud was 650 km wide.

tsunami warning

The explosion obviously caused a violent movement in the water of the Pacific Ocean: evacuations took place in particular in Japan. In Peru, nearly 10,000 km from the site of the eruption, two women were swept away by the waves and died. Unlike Chile and Ecuador, Peru had not closed its beaches in anticipation of the arrival of the waves caused by the explosion. In Tonga itself, 3 dead and 14 injured are reported, while people are still missing.

Best Instruments

“The duration of the eruption and the volume of material projected are not abnormal, but it is the force of the explosion which was really impressive, explains Fiona Ann Darbyshire. With the new ways of observing from satellites, it would seem that several aspects of this eruption have never been seen before by scientists, in particular with regard to the shock waves which crossed the globe. During the last comparable large explosions, the instruments were not so advanced. » M^me Darbyshire notes that, unlike past eruptions, the material ejected in this explosion was not large enough to alter Earth’s climate. “The eruption was of rare violence, but it was short-lived. To have an impact on the climate, duration is important. In the case of the Mount Pinatubo eruption in the Philippines in 1991, it was not as explosive, but the long duration of the eruption injected a lot more material in total into the atmosphere. This is what has had an impact on temperatures and climate. »