Tonga eruption was biggest explosion ever recorded, dwarfing nuclear blasts

They are energetic waves in the air that travel at the speed of sound and are able to maintain their shape along a path guided by the surface of the planet.

Scientists found Lamb wave pulses produced by the Tonga eruption were seen to circle the Earth at least four times.

In Reading, England, more than 16,000 kilometers from Tonga, the pulses began arriving about 14 hours after Hunga Tonga-Hunga Ha’apai’s eruption and immediately lifted the clouds.

“At the time, we had a laser cloud-base recorder looking at the cloud base and as the wave went through the cloud was perturbed,” Professor Giles Harrison, an atmospheric physicist at the University of Reading and co-author on one of the papers, told the BBC.

“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.”

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Where the Lamb waves coupled with ocean waves after the eruption, they generated tsunamis – not just in Tonga and New Zealand and other parts of the Pacific Ocean, but in the Atlantic Ocean and the Mediterranean Sea as well.

The audible shockwaves that were heard around New Zealand were also heard by people 10,000 kilometers away in Alaska.

A global network of detectors set up to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty picked up the infrasound signal, which indicated the blast produced an atmospheric pressure wave comparable with the biggest ever nuclear explosion – the Tsar bomb detonated by the Soviets in 1961 – but lasted four times longer.

New research is still to come on the cause of the tsunamis that struck Tongan islands in the immediate aftermath. Seafloor examination will determine how much, if anything, a collapse of part of the volcano contributed to them.

Stuff.co.nz

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