Scientists say they are astounded to understand the severity of the volcanic eruption that took place in Tonga in January. When the underwater mountain top exploded, it sent tsunami waves all over the world, spewing ash and water vapor into half of space.
The area surrounding the Pacific volcano was fully mapped by a survey by New Zealand and British warships. This map shows how the seafloor has been hollowed out and blasted by powerful debris currents stretching for 80 km (50 mi).
The New Zealand National Institute for Aquatic and Atmospheric Research Hunga-Tonga was responsible for the mapping operation at the Hunga-Haapai seamount (Niwa). According to the information obtained, the flood caused the displacement of at least 9,5 cubic kilometers, perhaps up to 10 cubic kilometers of material. This amount is almost equal to 4,000 Egyptian pyramids.
Ash and rock ejected from the caldera or opening of the volcano account for two-thirds of this amount.
A marine geologist and Niwa project director, Dr. Kevin Mackay described it as "a shotgun blast" sent skyward. He told BBC News that in this eruption, which is the tallest eruption column documented in human history, some of the material "reached even above the stratosphere and reached the mesosphere" (57km high).
The other third was formed by Hunga-top Tonga and material stripped from its sides falling down to spread to the ocean floor.
It was a mode of transporting pyroclastic density currents, which are avalanches of rolling, scalding rock and gas. In the water, their intense heat may have covered them with a frictionless cushion of steam, allowing them to run and run at extremely high speeds.
The research work followed streams that even managed to ascend and descend several hundred meters high.
This explains why, for example, the submarine cable connecting Tonga to the world wide web was cut.
Despite being 50 kilometers south of Hunga-Tonga and beyond a sizable ridge on the seafloor, a significant part of this data link has been omitted.
“Where these currents once were, nothing lives today. 70 kilometers from the volcano, it resembles a desert,” explains Dr. mackay. “Surprisingly, you can still discover life in areas escaping these density currents just below the rim of the volcano. The sponge was discovered. They escaped harm."
The Hunga-Tonga tsunami story also includes pyroclastic flows.
In addition to the Pacific, wave activity has also been experienced in the Atlantic and even in the Mediterranean.
According to the Niwa team, there were basically four different ways the water was moved to cause these tsunamis: density flows pushing the water out of the way; the explosive force of the explosion also repels water; dramatic collapse of the caldera floor (lowered by 700 meters); and the pressure waves of atmospheric explosion acting on the sea surface.