Volcanic risk: Separating the facts from the hype

Since Iceland’s Eyjafjallajökull volcano erupted in April 2010, wreaking havoc across European airspace, we’re now more sensitive to volcanic-related news. Let´s not forget that at its maximum impact, 75% of all European airline operations were closed, 10 million people were unable to travel for seven days, and airline losses reached $1.7 billion. And that was a small eruption in volcanological terms. But is the media now taking risk out of context?

A year ago, a study from U.K. scientists published in Nature Geoscience about Aira caldera, a volcanic complex near the city of Kagoshima, Japan, prompted the media volcano panic to claim a major eruption was imminent with catastrophic consequences. Nevertheless, the study from Dr. Jo Gottsmann´s group at Bristol University, in collaboration with scientists from Kyoto University in Kagoshima, was simply presenting a novel and innovative approach to help understand better the dynamics underneath the volcanic system, and, hence, make better predictions. That was the essence of the study, and by no means a statement on the when and how the next large eruption would be.

Last May, another article from U.K. scientists was published in Nature Geoscience, this time by Dr. Christopher Kilburn, UCL Hazard Centre, and colleagues from the Vesuvius Observatory in Naples, prompted the media to publish alarmist headlines on an imminent, catastrophic, super volcanic eruption in the South of Italy, wreaking havoc across the whole of Europe!

The old port at Pozzuoli in Southwest Italy. Ground uplift has raised the slip-ramp out of the water. Source: Christopher Kilburn, UCL Hazard Centre

The study, however, far from raising alarms, is an invitation to reflect on the way we’ve been looking at unrest episodes at Campi Flegrei, a volcanic complex in the South of Italy. They suggest the three major uplift episodes since 1950 that have raised its central district by about 3m without an eruption are likely to be part of a progressive approach to an eventual volcanic episode. If that’s the case, the signs of a future reawakening might not be so obvious and could take people by surprise. As the authors explain “unrest at large calderas rarely ends in eruption, encouraging vulnerable communities to perceive emergency warnings of volcanic activity as false alarms.” So yes, there’s an element of risk awareness in the study, but far from the super-volcano crying wolf. And what if there’s an eruption in Campi Flegrei?

Some background to set the scene

Volcanic calderas are depressions that result from the collapse of a magma chamber during a large eruption. The Campi Flegrei caldera lies on the western edge of the city of Naples and 24 km from its more famous volcanic neighbour Vesuvius. It is one of the Earth´s most hazardous calderas, because it’s so close to a large urban population. The caldera has been the site of volcanic activity for more than 50,000 years, with at least 61 eruptions in the last 15,000 years. The last eruption occurred in 1538, after 2,500 years of tranquility, and built the Monte Nuovo volcanic cone within a week (See picture).

Source: Christopher Kilburn, UCL Hazard Centre

The surface of the caldera has been bulging upwards since 1950 and has raised the port of Pozzuoli, near the centre of the caldera, by 3m. Of course, future activity from this volcano poses a serious threat to its 360,000 residents and the more than 3 million people living within 30 km, including the population of Naples. With the past episodes of uplift and swarms of volcanic earthquakes centered on Pozzuoli, there’s obvious concern the area may well be preparing for another eruption.

Source: Danielle Charlton, UCL Hazard Centre

Source: NASA Earth Observatory

Location, location, location.

Campi Flegrei was formed by two mega eruptions that expelled 300 km³ of magma about 39,000 years ago and another 50 km³ about 15,000 years ago. Such eruptions today would have catastrophic consequences, especially with more than six million people living within 100 km of the volcano.

Fortunately, eruptions since then have been much smaller (one-hundredth to one cubic kilometre each). A classic example is the Solfatara crater (see picture), about 1.5 km inland from Pozzuoli. It was formed during an explosive eruption about 3,850 years ago and is still thermally active, with “solfataric activity” (sulphur-rich gas emission) and continuous steam-driven activity linked to the underlying hydrothermal system. The gases are routinely monitored for signs of any change in composition caused by the approach of new magma.

Degassing at the Solfatara crater. Source: Christopher Kilburn, UCL Hazard Centre

If a new eruption occurs, it will most likely be similar in size to the events from the past 15,500 years. What’s not clear, though, is where the next eruption will happen. With scientific groups claiming it could be anywhere within 75 km² of the onshore half of the caldera, it could well be the case that you end up with a volcano in your garden if you live in Campi Flegrei.

Media news that leaves us aghast

The media are often quick to sensationalise risk. Confronting the challenges of understanding risk and increasing resilience is one of our aims at Willis Research Network. We aren’t denying the existence of volcanic risk here, but it’s important to put it in context and ensure proper interpretation to provide adequate risk advice. Both of the studies mentioned here show new and improved ways of understanding volcanic risk and be better prepared. Trying to over sensationalize scientific news might impact real emergency warnings of volcanic activity, making then look like false alarms.

Furthermore, the studies are raising awareness towards the risk of people being desensitized to the real hazards and risks of living in a volcanic area, often due to long periods of exposure. They do not suggest that neither the next unrest will lead to an eruption, or that the eruption will be massive or devastating. They offer an alternative way to interpret volcanic data, which ultimately should help improve resilience and set appropriate preparedness measures in the event of a new eruption. Perhaps this could be an invitation to reflect on exposure to volcanic hazard, and the feasibility of volcanic coverage.

About Rosa Sobradelo

Rosa Sobradelo is part of the Willis Research Network where she coordinates research activities in the areas of geo…
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