Perhaps that is why the powerful volcanic eruption in Tonga was so explosive

(ORDO NEWS) — By any measure, the Hunga-Tonga-Hunga-Hapai volcano eruption in January 2022 was massive.

It created a swirling plume of gas, dust and ash that rose 58 kilometers (36 miles) into the sky, atmospheric waves that circumnavigated the globe several times, and a tsunami in the Caribbean on the other side of the world.

A recently published study suggests why the scale of this volcanic explosion was so massive: a smaller eruption the day before prepared the volcano for a larger explosion, plunging its main vent below the ocean’s surface.

This meant that the molten rock was erupting directly into the sea water, vaporizing it along the way and amplifying the eruption. Evaporating sea water caused the lava to break into small pieces of ash, the researchers suggest.

Combined with ice crystals in the upper atmosphere, this cloud created static charges that led to lightning. The frenzy of electrical activity was so intense that it accounted for 80 percent of all lightning on Earth during its peak hour.

“We were really just trying to figure out what happened,” says volcanologist Melissa Scruggs of the University of California, Santa Barbara. “So we gathered all the information we could, all that was available during the first few weeks.”

Scruggs and her colleagues believe that almost 2 cubic kilometers (0.48 cubic miles) of material – weighing about 2,900 teragrams, or 2.9 thousand million metric tons – were sent halfway into space, causing strong ripples that were felt around the world.

The researchers found that the first two hours of the eruption were especially turbulent: it began at 5.02 p.m. local time. Approximately 12 hours later, activity at the facility faded. This is the largest eruption we’ve seen since the explosion of Mount Pinatubo in the Philippines in 1991, the researchers say.

The shockwaves that traveled across the Pacific caused numerous tsunamis around the world that often came earlier than expected because the models used to calculate them were based on earthquake activity rather than volcanic eruptions.

This is a warning about how dangerous underwater volcanoes can be, which include sea water. Many of them remain unobserved – they are in remote places, out of the view of satellite imagery – but the damage they can cause can be cataclysmic, as the Hunga-Tonga-Hunga-Hapai eruption showed.

“The volume of the eruption doesn’t really matter,” says geologist Frank Spera of the University of California, Santa Barbara. “What was special was how the energy of the eruption connected with the atmosphere and the oceans: a lot of energy went into the movement of air and water on a global scale.”

By the time the area had calmed down again, the islands of Hunga Tonga and Hunga Ha’apa were all but destroyed. These islands were created only in 2015, after another major eruption of the same volcano, they became the highest points of its crater.

The Hunga-Tonga-Hunga-Hapai volcano is a so-called stratovolcano – a cone-shaped variety that usually causes relatively little volcanic activity. It is one of a number of volcanoes fed by magma as a result of tectonic activity: the Pacific Plate is subducting under the Indo-Australian Plate.

Much more data will be collected over time, and more research can be expected on the causes and effects of the 2022 Hunga-Tonga-Hunga-Hapai eruption – and to ensure we are better prepared for the next eruption.

“Many aspects of this eruption await further study by multidisciplinary teams,” the researchers write in their published paper.

“It represents a golden opportunity for fundamental research into the complex, non-linear behavior of high-energy volcanic eruptions and associated phenomena, with critical implications for hazard mitigation, volcano prediction, and first-response efforts for future catastrophes.”


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