Something strange happened 15 minutes before the Tonga eruption: a signal imperceptible to humans crossed the Earth’s surface

It happened in 1912, then in 1937, in 1988, 2009, 2014… but 2022 was something completely different. On January 15 of that year, the Hunga Tonga volcano erupted again, but not in a “normal” way, injecting tons of gases into the atmosphere. No, that day he did it by injecting a huge amount of water vapor more than 10 kilometers high. So much steam that it made it one of the “main suspects” for the high temperatures of 2022. Now we know that the anomaly was accompanied by another fascinating moment.

Eruption and consequences As we said, that day the Hunga Tonga-Hunga Ha’apai volcano suffered one of the most powerful eruptions recorded in modern history in the Pacific Ocean. A catastrophic event, as it destroyed the island of the same name, covered Tonga in ashes, forced the mass evacuation of its inhabitants and caused the death of dozens of people.

To give us an idea, the explosion was so powerful that the ash column reached 58 kilometers high, reaching the mesosphere in just half an hour. Furthermore, the Hunga Tonga eruption surpassed even the Record-breaking 1991 eruption of Mount Pinatubo in the Philippines.

The “sign”. And now we come with the “big news”. Apparently, a team of scientists from the University of Tokyo has discovered that the eruption was preceded by an unusual seismic signalSo much so that we had never detected it before. This signal, known as a Rayleigh wave, traveled over the Earth’s surface 15 minutes before the eruption, but was not perceptible to humans.

The wave was detected by seismometers in Fiji and Futuna, about 750 kilometers from the volcano. Researchers say that this type of surface wave is common in earthquakes, but it was the first time it was linked to a large underwater volcanic eruptionwhich gives scientists a valuable clue for future predictions.

The importance of the Rayleigh Wave. In their recently published work they explain that the Rayleigh waveidentified as a precursor to the eruption, spread without any visible activity on the surface, which makes it, if possible, more especially relevant as a possible early warning signal.

A fascinating finding that has led researchers to consider its potential to improve prevention systems for natural disasters. Scientists believe that if the wave could be monitored in real time, the occurrence of volcanic eruptions could be anticipatedwhich would be vital for the evacuation and protection of populations at risk.

Seismic wave generation mechanism. The study also concludes that the Rayleigh wave was produced due to a fracture in the oceanic crust beneath the volcano. This fracture allowed the underground magma to mix with seawater, which destabilized the volcanic structure.

The pressure then increased to the point where the ground above the magma collapsed, triggering the gigantic eruption. This collapse of the volcanic caldera was precisely what allowed the expulsion of magma and gases with impressive force, causing the devastation observed in Tonga.

An unprecedented finding with future implications. There is no doubt, the discovery of this wave as a possible indicator is an advance that could be crucial for the science of volcanology. The only “but”: currently There are no real-time systems that use Rayleigh waves as a precursor to eruptions. According to Mie Ichihara, co-author of the study and volcanologist at the University of Tokyo, if infrastructure were developed to monitor these waves it would be possible to detect eruptions before their most destructive impacts.

Other detection systems and lessons for the future. In reality, the published scientific work is part of a broader effort to improve warning systems for natural disasters. For example, in 2021, another team of scientists discovered that tsunamis can be predicted through their magnetic fieldswhich arrive before changes in sea level. This and other findings underscore the importance of exploring different methods to detect and anticipate catastrophes, especially in a world increasingly affected by extreme weather events.

The researchers also indicate that the Tonga eruption could have been much more devastating if it had occurred in a densely populated area. The hope of scientists is that the knowledge gained from this unprecedented event will serve to improve warning systems and mitigate the impact of future disasters. Of course, the incorporation of advanced technologies in the monitoring of seismic waves such as Rayleigh along with other indicators will be key to avoiding disasters due to possible volcanic eruptions and associated tsunamis.

Image | NASA Earth Observatory

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