It was in mid-January earlier this year when people across the world woke up to strange occurrences, all caused by a single volcano that erupted in the Pacific island nation of Tonga.
Now that scientists have had enough time to study the eruption they confirmed it as the biggest explosion ever recorded in the atmosphere!
How big? Bigger than any 20th Century volcanic event, or even any of the atom bomb tests conducted after World War II.
The science community currently thinks that the Tonga volcanic eruption of January 15, 2022, is close in its intensity to another one that happened hundreds of years ago in Krakatoa in 1883. They believe that in terms of atmospheric disturbances that were caused, these two are actually quite similar. Fortunately, in 2022 scientists have access to advanced technology and amazing instruments, giving us a chance to understand these large-scale events like never before. So after months of studying the data and conducting assessments with modern instruments, scholars of the matter have finally released their findings for us to better understand what happened, why, and how!
Did you know that the gigantic explosion in Tonga did not happen all of a sudden? Before the volcano erupted, scientists had already been observing changes for several weeks caused by increased activity at the seamount, or underwater mountain where the eruption happened.
They were able to note several types of atmospheric pressure waves, along with other indicators like repeated booms that were heard by the people of Alaska 10,000km away from Tonga.
Thanks to the global network of detectors set up to monitor nuclear activity worldwide that ensures Nuclear-Test-Ban treaties are being followed, scientists were able to observe infrasound signals coming from the eruption site. Since infrasound has frequencies that are below what humans are capable of hearing, these modern instruments helped immensely in understanding this global event.
The Tonga volcano blast created an atmospheric pressure wave that can be compared to the biggest ever nuclear explosion – the Tsar bomb detonated by the Soviet Union (now Russia) in 1961, but lasted four times longer!
One of the key points that scientists observed is to do with something called the Lamb waves. Lamb waves, named after the early 20th Century mathematician Horace Lamb, are energetic waves in the air which spread at the speed of sound, along a path that is guided by the surface of the planet. These waves are also what scientists call ‘non-dispersive,’ which simply means that they hold and maintain their shape as they move through large distances. This makes them really easy to spot and record. After observing the collected data, scientists have confirmed that the Lamb wave pulses from the Tonga eruption circled the Earth at least four times.
Even the UK, a country that is 16,500km from Tonga, felt these pulses arriving on the evening of January 15. This was about 14 hours after the volcano actually erupted all the way on the other side of the planet. When these pulses arrived, they were so powerful they actually lifted the clouds over the UK for some time.
When the Lamb waves were combined with the powerful ocean waves, together they were able to generate tsunamis. No, not just one, and not just in the Pacific Ocean which is close to Tonga. Tsunamis were recorded even in the Atlantic Ocean and the Mediterranean Sea. All caused by this massive eruption on the seafloor.
Although we understand a lot more about underwater explosions, atmospheric activities and details of the incident, scientists are still investigating parts of it. – For example, getting a better understanding of the the generation of tsunamis that reached coastlines in the Tongan islands, for example better. Scientists are certain that some of these Tsunamis were caused by pressure waves from the volcano that pushed down on the water surface with considerable force. New projects that map the seafloor are now being started to help us all better understand the history of this incident and its future impact on the environment and us.
Prof Giles Harrison who is an atmospheric physicist at the University of Reading and one of the main scientists studying the explosion said it best, “If ever you wanted evidence that the atmosphere is a remarkably interconnected thing, this was it. And what happens on one side of the planet can propagate around to the other side at the speed of sound.”
We can’t deny that the incident has proved to all of us again how much the earth and its systems are connected to one another!
Did you learn something new today? Do you have any other cool facts about volcanic explosions that you want to share with us? Tell us in the comments section below.
Interested in geography? Well here is something that might interest you. Did you know that scientists have discovered the 8th continent Zealandia?
Read more about the Earth’s fascinating geography and ecology in our Science Feed:
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