Massive explosion equal to five nuclear bombs triggered Tonga volcanic eruption

The team's model proposes that the event resulted from a gas-compressed rock being trapped underwater, similar to an overcooked pressure cooker.

In Short

• The researchers analysed seismic records of the climactic event
• The eruption was caused by an explosion of gas-compressed rock
• The water from explosion was enough to fill about one million Olympic-sized swimming pools

New research from The Australian National University (ANU) has uncovered the primary trigger behind the massive Hunga Tonga underwater volcanic eruption that occurred two years ago.

The study, led by a team of student seismologists, sheds light on one of the largest volcanic events in recent history.

The researchers analysed seismic records of the climactic event to decipher its mysterious physical mechanism. Their findings, published in Geophysical Research Letters, suggest that the eruption was caused by an explosion of gas-compressed rock trapped beneath shallow waters.

Jinyin Hu, a PhD student and co-author of the study, explained that the energy released by this explosion was equivalent to five of the largest underground nuclear tests conducted by North Korea in 2017.

The team's model proposes that the event resulted from gas-compressed rock being trapped underwater, similar to an overcooked pressure cooker.

This discovery challenges the common belief that such massive underwater eruptions are caused by the interaction of hot magma with cold seawater. The researchers employed a technique previously developed for studying underground explosions to analyze this natural phenomenon.

Dr. Thanh-Son Pham, another co-author, noted that the explosion caused a massive vertical push of water into the atmosphere, generating tsunamis up to 45 meters high at nearby islands.

The volume of water uplifted during the event was estimated to be enough to fill about one million Olympic-sized swimming pools.

Professor Hrvoje Tkalcic, a study co-author, highlighted the significance of seismic waveform modeling in understanding the event. The team observed a substantial upward vertical force during the eruption, which they attributed to the solid earth rebounding after the water column was lifted.

The Hunga Tonga eruption is considered one of the best instrumentally recorded events of its size in recent history. The researchers emphasized the importance of multiple recording methods, including satellite imagery and seismic sensors, in capturing the event's full scope.

The ANU team believes that monitoring gas releases and micro-seismicity from volcanic sites could help better prepare for future events of this magnitude.

This groundbreaking research not only provides crucial insights into the Hunga Tonga eruption but also demonstrates the power of academic curiosity and forensic seismology in unraveling complex geological phenomena.