Canberra, Australia – Two years after the monumental eruption of the Hunga Tonga underwater volcano, researchers at The Australian National University (ANU) have made significant headway in uncovering the mysterious catalyst behind one of the largest volcanic eruptions in recent history. Led by a dedicated team of student seismologists, new findings suggest an unexpected trigger, likened to an intense buildup of pressure akin to an “overcooked pressure cooker.”
This recent study, spearheaded by the efforts of ANU Ph.D. student Jinyin Hu, utilized seismic data to analyze the eruption’s underlying mechanics. The results indicated that the explosive power released during the event equaled the energy of the five largest underground nuclear detonations by North Korea in 2017. “Our model suggests that gas-compressed rock trapped beneath the shallow seabed was the main driver of the eruption,” Hu explained.
Traditionally, it was assumed that such massive eruptions resulted from the interaction between hot magma and cold seawater. However, this new research introduces a shift in understanding, highlighting a different interaction beneath the sea floor.
Dr. Thanh-Son Pham, another co-author of the study, discussed the immediate aftereffects of the eruption, particularly the immense displacement of water. “The explosion triggered a substantial vertical push of water, launching massive volumes into the atmosphere and generating tsunamis up to 45 meters high impacting nearby islands,” he said. According to the research, the volume of water displaced was sufficient to fill approximately one million Olympic-sized swimming pools.
Further insights were provided by Professor Hrvoje Tkalčić, who elaborated on the seismic findings. “Our use of seismic waveform modeling helped us identify a significant upward force during the eruption, initially puzzling us. We later understood this as the solid earth rebounding upwards following the massive upward shift of water.”
The Hunga Tonga event, thanks to advancements in seismic technology and data collection, stands as the best instrumentally recorded volcanic event of its size to date. “We now have sophisticated monitoring systems capturing a range of data from satellite imagery to seismic sensors,” Hu added. This was not the case during the similarly monumental 1991 eruption of Mount Pinatubo in the Philippines, where technological limitations restricted detailed data capture.
The implications of the ANU team’s research extend beyond academic curiosity. By studying the gas emissions and tiny seismic shifts at volcanic sites, scientists can potentially forecast similar catastrophic events, thus enhancing preparedness and response strategies.
This breakthrough in understanding comes as part of a broader effort to use seismology to untangle complex geological events around the world. Just weeks earlier, researchers applied similar techniques to investigate a sequence of events in Greenland, including a landslide triggered by glacial melting and a prolonged seiche observed globally.
As the scientific community continues to unlock the secrets of Earth’s subterranean forces, studies like these not only shed light on the mysterious mechanisms behind natural disasters but also pave the way for innovations in how we predict and manage these formidable events. The full findings from this latest research have been published in the Geophysical Research Letters journal, offering a detailed composite seismic source model for this monumental volcanic eruption.