Underwater volcanic eruption off Tonga triggered 300ft mega-tsunami

By Mark Waghorn via SWNS

An underwater volcanic eruption off Tonga triggered a 300 feet mega tsunami – tall enough to submerge a 25-story building, according to new research.

Scientists say it was the biggest for at least 140 years - rivaling notorious Krakatoa in 1883.

Complex landforms in the region acted as a "low velocity trap" lasting over an hour capturing 279-foot waves - just a minute after the initial blast.

Ash and rock soared more than 60 miles into the upper atmosphere - knocking out radio communications, GPS systems and telescopes.

The findings are based on computer simulations of swelling waters across the archipelago.

Miraculously, there were only three confirmed deaths - despite whole communities being left under a blanket of mud and debris from the massive flood that followed.

Lead author Professor Sam Purkis, of the University of Miami, said: "Despite its size and long duration, the mega-tsunami that resulted from Hunga Tonga-Hunga Ha'apai claimed few lives.

"The main factors that led to this, we suggest, are the quirk of the location, the Covid-19 pandemic and increased evacuation drills and awareness efforts carried out in Tonga in the years prior to the eruption."

The eruption in January 2022 was hundreds of times more powerful than the nuclear bomb dropped on Hiroshima to end the Second World War.

Prof. Purkis and colleagues combined before-and-after satellite imagery, drone mapping and field observations.

Results showed waves up to 148 feet high along the coast Tofua Island and 56 feet on Tongatapu, the country's most populated island.

Hunga Tonga-Hunga Ha'apai forms the island chain of Tonga. It is a result of the convergence of the Pacific and Indo-Australian tectonic plates.

The simulation also suggested that the eruption location relative to urban centers saved Tonga from a worse outcome.

Prof Purkis said: "While 2022 may have been a lucky escape, other submarine volcanoes possess the capacity to spawn a future tsunami at the same scale.

"This eruption holds important lessons for both past and future tsunami in Tonga and beyond.

"The eruption was an excellent natural laboratory to test hypotheses and models that can be deployed elsewhere to improve future disaster preparations, and better understand similar eruptions and subsequent tsunami as preserved in antiquity and in the geologic record."

The August 1883 eruption of Krakatoa was the worst in modern history.

The volcano, found in the middle of the Sunda Strait in between two of Indonesia’s largest islands, was on a small island which disappeared almost overnight.

The eruption was so loud it could be heard in Reunion, some 3,000 miles away. As the volcano collapsed into the sea, it generated a tsunami more than 120 feet high.

It destroyed 300 towns and villages, and killed more than 36,000 people. If it were to erupt again with such force and fury – as is likely to happen – it would cause even more devastation.

The study is published in the journal Science Advances.