A team of scientists from the Australian National University has pinpointed the pivotal event behind the massive underwater eruption of the Hunga Tonga volcano in the Pacific Ocean in January 2022. The research, published in Geophysical Research Letters, offers a detailed mechanism grounded in seismic data and modern rock mechanics. The eruption, one of the most powerful events in recent memory, sent shock waves around the planet, disrupted atmospheric conditions, and influenced oceanic behavior. While the dramatic plume and ensuing tsunami captured headlines, the underlying trigger required careful investigation and new analysis.
For years, researchers weighed several scenarios from magma overpressure to gas-driven explosions or sudden crustal failure. The new study narrows the culprit to a subterranean explosion produced by compressed rock beneath the shallow seafloor, releasing energy comparable to the combined yields of multiple large-scale tests. This finding reframes how scientists view submarine volcanism and the dynamics of explosive rock failure under high confining pressure.
To reach this conclusion, the investigators analyzed dense seismic records collected by regional networks. They reconstructed the sequence of faulting and rock breakdown, measuring the timing of fracture events and gas release. The approach blended rock mechanics with the role of trapped gases, showing how rapid compression under shallow seawater can trigger a sudden, violent release of energy that propagates through the surrounding medium.
The core result describes gas-rich rocks beneath the seafloor that became trapped as the surface water above remained relatively shallow. Heat and pressure caused those rocks to fracture abruptly. The explosion carved a path through the crust, unleashing an enormous burst of energy—an amount equated to the combined yield of five nuclear detonations conducted in 2017. This energy generated a strong shock wave that traveled through water and air, driving the atmospheric disturbance and producing the notable tsunami.
“Our model suggests that the event occurred when gas-compressed rocks became trapped beneath the shallow sea, as if in an overheated pressure cooker,” the study’s authors explained. This vivid analogy helps convey how confinement and rapid pressure release can unleash extreme energy in a relatively small volume of rock, with far-reaching consequences.
Observers noted that the explosive energy propelled a powerful atmospheric shock, while the associated tsunami reached significant heights near the rupture zone. In this event, waves rose to substantial levels and propagated across the Pacific, affecting coastlines far from the eruption site. The analysis underscores how submarine explosions can have both immediate local effects and remote, long-range consequences for island communities and coastal regions.
Seismologists emphasize that ongoing monitoring of gas emissions and microseismic activity around volcanic regions is essential for improving preparedness for similar eruptions in the future. The findings highlight the value of integrated observation networks that track subsurface gas dynamics, rock stiffness, and small tremors, helping scientists detect early warning signs and refine hazard models for Pacific grabens and similar settings worldwide.
Earlier assessments suggested that the Tonga eruption might influence climate over extended periods, an area still under study. Since 2022, researchers have explored how the eruption’s atmospheric aerosols and heat release could interact with global climate patterns, contributing to short-term fluctuations and influencing atmospheric chemistry for years to come. This evolving understanding informs climate scientists and policymakers as they assess regional and global impacts of large submarine eruptions.
For readers in Canada and the United States, the research reinforces the importance of resilient coastal monitoring systems and rapid warning protocols for submarine eruptions and tsunamis. By combining seismic data with oceanographic and atmospheric observations, authorities can strengthen preparedness and response strategies, protecting communities along the Pacific margins and supporting regional risk-reduction initiatives.