Tonga volcano eruption unleashed power of 5 nuclear bombs, students reveal

Two years ago, the Hunga Tonga underwater volcano erupted with devastating force. It was one of the largest volcanic events in recorded history. But until now, the cause of this cataclysmic event remained a mystery.

A team of student-led seismologists from The Australian National University (ANU) has finally uncovered the trigger for this volcanic eruption.

They studied the seismic data to understand the cause of the eruption.

“Our findings confirm there was an explosion, possibly due to a gas-compressed rock, which released energy that equated to five of the largest underground nuclear explosions conducted by North Korea in 2017,” said Jinyin Hu, study co-author and ANU PhD student.

“Our model suggests the event resulted from the gas-compressed rock being trapped underneath a shallow sea, like an overcooked pressure cooker. This would be surprising to many because it had been commonly thought that the interaction of hot magma with cold seawater caused such massive underwater volcanic eruptions,” Hu explained.

Seismic modeling

Hunga Tonga volcano event occurred in the South Pacific Ocean on January 15, 2022.

It caused significant destruction. It released a huge amount of energy, triggering a tsunami that reached incredible heights and damaged buildings and other infrastructure including underwater cables.

The eruption also released a massive amount of ash and debris into the atmosphere, which had a significant impact on the global climate.

Since then, numerous studies have been undertaken to investigate its subsequent effects and the underlying causes.

For instance, a recent study found that the enormous amount of aerosols and water vapor emitted by the Tonga eruption had a temporary cooling effect on the planet due to their ability to block sunlight.

In this new study, the ANU team adapted a seismic waveform modeling used for studying underground explosions to analyze the natural explosion of the Tonga volcano.

The researchers determined that the explosion caused a tremendous vertical upward surge of water into the atmosphere. This possibly triggered tsunamis that reached 45 meters tall on nearby islands.

“The water volume that was uplifted during the event was huge. Based on our estimates, there was enough water to fill about one million standard Olympic-sized swimming pools,” said Thanh-Son Pham, the study co-author.

Best recorded event

The researchers were initially puzzled by the seismic data they observed from the Tonga eruption. They noticed a significant upward force, which was unexpected. However, upon further analysis, they realized that this upward force was due to the Earth’s surface rebounding.

“We realized that the solid earth rebounded upwards after the water column got uplifted,” noted Professor Hrvoje Tkalčić, the study co-author from ANU.

The ANU seismologists believe that the Tonga eruption is the “best instrumentally recorded” event of its kind and size in recent history.

Interestingly, this massive event was documented using various monitoring systems, such as satellite images and seismic sensors, which collected data on sound waves and the Earth’s structure. This has helped to piece together the mysteries of the massive explosion.

“There was another event that happened in 1991 that was a similar size in Pinatubo in the Philippines, but back then, monitoring systems weren’t as sophisticated as they are now,” added Hu in the press release.

The team proposes that closely observing the release of gases and subtle tremors from volcanic sites can improve our ability to anticipate and mitigate the risks posed by future volcanic events.

The findings were published in the journal Geophysical Research Letters.