When his phone rang at 3.22am last Wednesday, 50-year-old Giuseppe Salerno, the head of volcanologists at Catania’s National Institute of Geophysics and Volcanology (INGV), was already up after a thundering rumble had awoken many of the city’s inhabitants. The call came from the headquarters of the INGV where, a few seconds before that disturbance, seismic waves on one of the 40 monitors in the operations room seemed to jump off the screen. For the 14th time in less than a month, Mount Etna had sent another reminder that it is one of the world’s most active volcanoes.
Etna, 3,300 (10,800ft) metres above sea level, has been in explosive form in recent weeks, spewing incandescent magma and a copious shower of ash that has reached as far as Catania. Since 16 February, with fastidious precision, every 48 hours the volcano has put on a firework display with lava fountains reaching as high as 2,000 metres.
For three days the Guardian had access to the rooms of the INGV in the Piazza Roma, Catania, where day and night 100 Italian scientists monitor Etna’s movements in an attempt to explain these recent phenomena.
“The recent activity is part of a so-called lava fountaining that is among Etna’s normal activities,” says Salerno, a former PhD researcher at Cambridge University’s department of geography. “What is really peculiar is that the volcano is behaving like a machine, with rhythms that have almost a mathematical precision. This is why we’ve been monitoring its every breath, rumble and quiver in recent months.”
The information recorded by the 150 monitoring stations located over the 460 sq miles of the volcano, including heat-sensor cameras, gas emission detectors and seismographs, is sent in real time to the control room and broadcast on dozens of monitors, which give the impression of a war room in a spy movie.
“You have to imagine this control room like a hospital,” adds Salerno, “with dozens of doctors working for the same patient: Etna, who in recent weeks has been manifesting peculiar symptoms. From here we can monitor its heartbeat with the seismographs or its breathing with the gas detectors.”
The recent eruptions have provoked some distress for people living on the volcano, with ash rains that have blanketed streets, squares and buildings. In recent weeks in the town of Giarre alone more than 12,000 tonnes of ash have fallen. “It’s an extremely dramatic situation, an emergency, says Alfio Previter, a council official. Salerno said: “We’re literally buried, and if this keeps up, many towns will go bankrupt in their attempt to remove the ash, which could cost hundreds of thousands of euros.”
According to Italian law, ash collected from the streets and squares, and mixed with other forms of urban waste, is considered a special refuse, which increases the cost of its disposal. Proper disposal of a cubic metre of volcanic ash costs about €20 (£17).
However, Salerno, whose career has taken him to Kīlauea in Hawaii and the volcanoes of Central America, explains that the key to unlocking the mystery of Etna’s unusually spectacular eruptions is precisely the volcano’s ash.
In an underground laboratory of the INGV, Lucia Miraglia, 53, a geologist and volcanologist who has studied Etna’s ash under a microscope for the past 20 years, recently made a revealing discovery: “Studying the ash that’s fallen in recent days, we noticed that it reflects what volcanologists call ‘primitive magma’; that is, a magma that comes from the bowels of the mountain and carries a greater charge of gas, which is the reason why we are seeing these strikingly tall lava fountains. This sort of fresh magma has been seen before, but what’s peculiar is that the magma that Etna has been spewing since 16 February is the most primitive I’ve studied in the last 20 years.”
Etna’s magma originates from several reservoirs located miles underground. Experts at the INGV estimate that Etna’s main reservoir, and also its largest, is 12km (7.5 miles) underground. The Sicilian geophysicist Rosanna Corsaro, who studies Etna’s core from INGV headquarters, says: “The magma that’s been surfacing in these recent eruptions seems to come from about 10km underground.”
Recently, Etna has been going through a period in which there is a very efficient transfer of magma from deep beneath the surface. The south-east crater – which has been spewing lava in recent weeks – has until now been functioning as a safety valve. Other scenarios cannot be excluded, however. “Sometimes primitive magma eruptions are lateral: that is, when fractures appear on the side of the volcano and give rise to this sort of activity,” says Corsaro. “It could be that at a certain point this valve may no longer function efficiently. In that case, if the primitive magma continues to rise to the surface, a lateral opening could form.”
Such “flank eruptions” are the ones volcanologists most fear, as lava flows down the sides of the volcano, opening fractures on the low-lying mountains that risk inundating the cities below.
Forty years ago, shortly after lunch on 17 March 1981, a lateral eruption unleashed one of the most dramatic lava flows in the history of the volcano. Fortunately, it lasted only a few days, but its volume buried forests, homes, streets and railway lines, threatening to transform the small town of Randazzo into a new Pompeii. Estimates of the total volume of lava in that event are in the range of 30m cubic metres (1bn cubic ft).
But the most destructive flank eruption occurred in 1669, when lava, accompanied by earthquakes, buried dozens of towns and even reached the sea.
“At this time, the volcano’s recent activity doesn’t suggest that there will be a flank eruption,” says Stefano Branca, the director of the INGV in Catania. “It is clear, however, that Etna is no stranger to lateral eruptions. It’s not a matter of risk: lateral eruptions will happen at some point in the future.
“When?” he adds. “Well, only God knows when.”