Underwater 'booms' could revolutionize our ability to predict and prepare for deadly volcanic tsunamis. The recent eruption of Hunga volcano in Tonga serves as a stark reminder of the unpredictable nature of these natural disasters. While the initial explosions and tsunamis were well-documented, it was the subsequent collapse of the volcano's caldera that truly caught the world off guard.
What makes this discovery so significant is the realization that the underwater collapse produced an audible signal detectable thousands of kilometres away. By re-analysing seismic data, researchers identified the moment when the caldera began to collapse, generating a powerful T-wave that radiated across the Pacific. This finding opens up a new avenue for early warning systems, as these underwater signals could potentially provide timely alerts for communities at risk.
The challenge of monitoring submarine volcanoes is well-known. With hundreds scattered around the Pacific Ring of Fire, our understanding of their activity and potential eruption responses is limited. Satellites and conventional seismometers have their limitations, especially in detecting the subtle signs of an impending tsunami. However, the discovery of these underwater 'booms' offers a promising alternative.
The key lies in the efficient transmission of underwater sound over long distances as hydro-acoustic signals known as tertiary waves (T-waves). An isolated volcano can act like a bell, radiating the sounds of violent underwater processes. By re-analysing seismic data, researchers were able to 'hear' submarine landslide flows and, more importantly, the collapse of the caldera, which produced the most destructive local tsunami.
The case study of the Kanokupolu telecommunications tower further highlights the potential of this approach. The tower's destruction provided a precise timestamp, indicating when the tsunami arrived and confirming the timing of the caldera collapse. This evidence, combined with eyewitness accounts, allowed researchers to reconstruct the sequence of events that conventional seismic monitoring might have missed.
The implications are profound. If monitoring systems can automatically recognize and locate these underwater signals, they could provide early warnings for volcanic tsunamis, similar to existing systems for earthquake-induced tsunamis. This could potentially save lives and minimize the devastating impact of these natural disasters. As we continue to study and understand these phenomena, the integration of advanced monitoring techniques and early warning systems becomes increasingly crucial in building resilience against nature's unpredictable forces.
