In 2022, the Hunga Tonga-Hunga Ha’apai underwater volcanic eruption shocked the world, sending massive tsunamis and plumes of ash into the sky. New research from The Australian National University (ANU) has finally shed light on the trigger behind one of the largest volcanic eruptions in history. This cataclysmic event, which had puzzled the scientific community for two years, is now better understood thanks to groundbreaking research led by a team of ANU seismologists.
The Mystery Behind the Eruption
The Hunga Tonga underwater volcano eruption was a record-breaking event, leaving scientists searching for answers about its cause. Until recently, many believed that the eruption was caused by the interaction between hot magma and cold seawater. However, the student-led team at ANU has revealed a surprising new trigger: an explosion equivalent to the force of five of the largest underground nuclear bombs ever detonated.
“Our findings confirm that the eruption was triggered by an explosion, likely due to gas-compressed rock, which released energy comparable to five underground nuclear tests conducted by North Korea in 2017,” said Jinyin Hu, an ANU PhD student and co-author of the study.
Hu explained that the gas-compressed rock, trapped beneath a shallow sea, acted like an “overcooked pressure cooker.” The explosive release of energy was powerful enough to send shockwaves and trigger the massive eruption, creating a force that shook the earth and ocean alike.
A Massive Explosion That Shook the World
Study co-author Dr. Thanh-Son Pham explained the magnitude of the explosion and its devastating consequences. The event caused a massive vertical displacement of water, sending it skyrocketing into the atmosphere and generating tsunamis that reached as high as 45 meters (148 feet) on nearby islands. The researchers estimated that enough water was displaced to fill around one million Olympic-sized swimming pools.
“The water volume that was uplifted during the event was immense,” Dr. Pham said. “This vertical push of water was one of the main causes behind the deadly tsunamis that impacted the region.”
Further supporting this explanation, the research team used seismic waveform modeling to analyze the eruption. They observed a significant vertical force pointing upward during the event, which they initially found puzzling. However, they soon realized that the solid earth rebounded after the enormous water column was displaced, providing further evidence of the explosion’s immense power.
Advanced Seismic Techniques Reveal the Truth
To uncover the mechanism behind the eruption, the researchers employed a technique initially developed to study underground explosions. This forensic seismology approach, often used to detect nuclear tests, enabled the team to accurately analyze the seismic records of the eruption. The event's seismic signature revealed clear similarities to the seismic patterns of underground nuclear explosions, confirming the explosion's extraordinary force.
Study co-author, Professor Hrvoje Tkalčić of ANU, praised the role of seismology in unraveling this mystery: “With Hunga Tonga, we have a short-duration explosive event observed globally. The academic curiosity and forensic seismology applied in this research represent scientific investigation at its best.”
The eruption’s impact was felt around the globe, and it remains one of the best-recorded events of its kind. The team’s use of advanced monitoring systems—ranging from satellite imagery to seismic sensors—allowed them to piece together a detailed picture of what happened. According to Jinyin Hu, “This is one of the largest events in our lifetime, and fortunately, we had multiple ways to record and study it.”
Lessons for the Future
The Hunga Tonga eruption, along with the 1991 eruption of Mount Pinatubo in the Philippines, ranks as one of the most significant volcanic events of the modern era. However, unlike the Pinatubo eruption, which occurred during a time when monitoring technology was less advanced, the Tonga eruption was recorded by sophisticated systems, providing valuable data for scientists.
The research team emphasized the importance of continued monitoring of volcanic sites. By closely observing gas releases and seismic activity, they believe scientists can better prepare for future eruptions and potentially mitigate their destructive impacts.
As the world continues to grapple with the risks posed by natural disasters, understanding the forces behind them—like the explosion that triggered the Hunga Tonga eruption—is critical. The research from ANU offers not only an explanation for this historic event but also vital insights that could help prevent future catastrophes.