How Do We Know When a Volcano Is about to Erupt?

In a world where concerns about climate change and global warming are rampant right now, monitoring the weather is currently more relevant than ever. When it comes to natural phenomena and disasters such as volcanoes, earthquakes and tsunamis, the ability to predict an imminent event is even more important, since it can directly save hundreds and thousands of lives.

Regarding volcanoes, it can be incredibly difficult to know when exactly an explosion is about to occur. This is largely due to the fact that every contemporary study seems to contradict or disagree with ones before it, meaning scientists know they still have much to learn.

This is certainly true with regards to a study published in the journal Earth and Planetary Science Letters earlier this month, which found that the vast majority of the time, explosions occurred with no seismic activity in the immediate build-up to the release. This data is in stark contrast to existing ideas about how to determine when a volcano is about to erupt.

Previously existing methods of detecting a volcano eruption

Prior to the latest study, volcanologists usually relied on one or more of three tell-tale signs which indicated that an eruption was likely. These comprised of:

• Increased groundswell in the immediate vicinity of the volcano, indicating a build-up in magma and elevated pressure levels on the rock itself.
• A higher concentration of gases at the vent of the volcano, including such gases as carbon dioxide, sulphur dioxide or water vapour, which suggests that the magma is nearing the surface and an explosion is imminent. The presence of sulphur in particular is why many people have reported the smell of rotting eggs immediately prior to an eruption.
• Seismic patterns beneath the surface of the land itself, demonstrative of the movement of magma as it fills up individual chambers or forces its way to the vent.

Previously, it was generally accepted that the majority of volcano eruptions would be preceded by at least one of these three phenomena, giving scientists and eco-teams time to predict the catastrophe and evacuate the area. However, the new data has blown such hypotheses out of the magma.

Nicaraguan study subverts beliefs

The new study was conducted by a team of geophysicists and led by Diana Roman from the Carnegie Institute for Science. It concentrated entirely on Telica Volcano in Nicaragua, with data being gathered between 2009 and 2013.

In those four years, the team used new instruments to gain new insights on volcanic emissions, measuring every physical aspect of the volcano imaginable within a 2.5-mile radius. This allowed them to record data on 50 different eruptions during that time – and remarkably, 96% of those explosions occurred with absolutely no seismic activity immediately preceding the eruption.

48 instances occurred without any activity in the five minutes leading up to the event, while 35 displayed no activity for a full half hour before eruption. In the longest instance, there had been no demonstrable activity for a whopping 619 minutes (10.3 hours) – which, incidentally, was also the largest and most forceful explosion.

As a result, scientists now believe there is a direct correlation between the seismic activity (or lack thereof) in the direct run-up to the eruption, since its absence could indicate mounting pressure inside the volcano. Although the results are far from conclusive, it is one more strand of information to add to our increasing body of knowledge on these fascinating but destructive wonders of the natural world.