Eruption of Campi Flegrei would put area occupied by 500,000 people at risk, say scientists 
 
 The slumbering Campi Flegrei volcano under the Italian city of Naples shows signs of reawakening and may be nearing a critical pressure point, according to a new study. 
 
 Italian and French scientists have for the first time identified a threshold beyond which rising magma under the Earth’s surface could trigger the release of fluids and gases at a 10-fold increased rate. 
 
 This would cause the injection of high-temperature steam into surrounding rocks, said Giovanni Chiodini, a researcher at Italy’s National Institute of Geophysics and Volcanology in Bologna. “Hydrothermal rocks, if heated, can ultimately lose their mechanical resistance, causing an acceleration towards critical conditions,” he told AFP by email. 
 
 He said it was not possible to say when – or if – the volcano would erupt but “it would be very dangerous” if it did for about 500,000 people living inside and near the caldera – the bowl-like depression created after a volcano blows its top. 
 
 Chiodini said there was an urgent need to obtain a better understanding of Campi Flegrei’s behaviour because of the risk to such a dense urban population. 
 
 Since 2005, Campi Flegrei has been undergoing what scientists call uplift, causing Italian authorities to raise the alert level in 2012 from green to yellow, signalling the need for active scientific monitoring. The pace of ground deformation and low-level seismic activity has recently increased. 
 
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 Two other active volcanoes – Rabaul in Papua New Guinea and Sierra Negra in the Galapagos – “both showed acceleration in ground deformation before eruption with a pattern similar to that observed at Campi Flegrei,” Chiodini said. 
 
 
 
 The Campi Flegrei caldera was formed 39,000 years ago in an explosion that threw hundreds of cubic kilometres of lava, rock and debris into the air in the largest eruption in Europe in the past 200,000 years. Campi Flegrei last erupted in 1538, though on a much smaller scale. 
 
 Nearby Mount Vesuvius, which had a massive eruption in AD79 that buried several Roman settlements including Pompeii, is also classified as an active volcano. 
 
 The study co-authored by Chiodini was published on Tuesday in the scientific journal Nature Communication. ||||| In this educational film, researchers explain the dangers residents face living near the area of the Campi Flegrei volcano, near the Italian city of Naples. (YouTube/UPStrat-MAFA) 
 
 The Italian name for the volcano — Campi Flegrei, or “burning fields” — is apt. Its caldera, the collapsed top of the ancient volcano that formed when the magma within erupted, is almost 8 miles wide. Though half of the caldera is obscured beneath the crystal blue waters of the Mediterranean, the other half is on land studded with cinder cones and craters from smaller eruptions. The whole area seethes with hydrothermal activity: Sulfuric acid spews from active fumaroles; geysers spout water and steam; the ground froths with boiling mud; and earthquake swarms shudder through the region, 125 miles south of Rome. 
 
 And things seem to be heating up. Writing in the journal Nature Communications on Tuesday, scientists report that the caldera is nearing a critical point at which decreased pressure on rising magma triggers a runaway release of gas and fluid, potentially leading to an eruption. 
 
 Forecasting volcanic eruptions is a famously dicey endeavor, and right now, it's impossible to say if and when Campi Flegrei might erupt, according to lead author Giovanni Chiodini, a volcanologist at the National Institute of Geophysics in Rome. But now more than ever, the caldera demands attention: An eruption would be devastating to the 500,000 people living in and around it. 
 
 The site's last major eruption happened over the course of a week in 1538, when it expelled enough new material to create the cinder cone mountain Monte Nuovo. 
 
 But the caldera itself is some 39,000 years old, formed by an eruption larger than anything else in the past 200,000 years of European history. A 2010 study in the journal Current Anthropology suggested that this prehistoric outburst — which spewed almost a trillion gallons of molten rock and released just as much sulfur into the atmosphere — set off a “volcanic winter” that led to the demise of the Neanderthals, who died out shortly afterward. 
 
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 Today, the Campi Flegrei caldera is increasingly restless. For half a century, scientists have measured “bradyseism” events — slow movements of the ground — that are indicative of molten rock slowly filling the mountain's magma chamber. Significant uplift in the past decade prompted Italian authorities to raise the supervolcano's alert level from green (quiet) to yellow (scientific attention) in 2012. 
 
 “These areas can give rise to the only eruptions that can have global catastrophic effects comparable to major meteorite impacts,” Giuseppe De Natale, head of a drilling project to monitor the caldera, told Reuters after that change was made in 2012. 
 
 Now, Chiodini and his colleagues have identified the volcano's “critical degassing pressure” — a vital data point in understanding the likelihood of an eruption. As molten rock from Earth's interior rises through the crust, it is subject to less pressure, and this decline in pressure causes volatile gases dissolved within it to be released. At the critical degassing pressure point, this process accelerates tenfold. Huge amounts of steam are injected into the surrounding rock. 
 
 If the magma loses too much water, it may harden and cease its upward motion, stopping the eruption in its tracks. 
 
 Alternatively, the injections of steam could destabilize the rock, accelerate the deformation process, and ultimately cause the volcano to blow. 
 
 Chiodini said scientists have seen an increase in ground deformation and low-level seismic activity around the caldera in recent years. This pattern compares with activity seen around similar volcanoes before their eruptions. 
 
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 This doesn't mean residents of Naples should be heading for cover. 
 
 “In general, unfortunately, volcanology is not a precise science,” Chiodini wrote in an email. “We have many uncertainties and long-term previsions are at the moment not possible! For example, the process that we describe could evolve in both directions: toward pre-eruptive conditions or to the finish of the volcanic unrest.” 
 
 What's more, volcanoes operate on time scales far beyond the scope of most scientific records. Campi Flegrei has had a major eruption only twice in the past 40,000 years, and both happened long before the invention of the first writing systems, let alone seismometers. There are written accounts of the 1538 eruption, but there are limits to the scientific insight those descriptions they provide. 
 
 What they lack in data, however, they make up for in vividness. Take this recollection, written by Italian philosopher Simone Porzio: 
 
 “The large tract of land which lay between the foot of the mountain . . . and the sea . . . was seen to rise and take the form of the newly produced mountain. And on the same day, at the second hour of the night, this mount of earth opened like a mouth, with a great roaring, vomiting much fire and pumice and stones.” 
 
 Correction: This article originally misidentified the journal in which the study was published. It is Nature Communications, not Nature. 
 
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 A massive underwater volcanic eruption is captured in real time ||||| Image copyright EPA Image caption The three fell into a pit that opened up as the parents tried to save their son 
 
 A boy and his parents have died after falling into a pit in a volcanic crater at Solfatara near Naples. 
 
 The drama unfolded during a family trip at the end of the school holidays, when the 11-year-old walked past a barrier into a prohibited area. 
 
 When his parents tried to pull him to safety, part of the crater collapsed and they fell 3m (10ft) into a hole. 
 
 It is thought all three were overcome by fumes. Their seven-year-old son did not enter the crater and survived. 
 
 Solfatara of Pozzuoli is one of a number of volcanoes to the west of Naples and is popular with tourists. A dormant volcano that last erupted in 1198, it has a shallow crater and is known for its sulphurous fumes and emissions of steam. 
 
 Crumbling quicksand 
 
 The family was visiting from Meolo near Venice in north-eastern Italy, reports said. The parents were both in their forties. Italian reports named the three as Massimiliano Carrer, Tiziana Zaramella, and their son, Lorenzo. 
 
 Image copyright EPA Image caption The hole in the crater was visible along with the chains that rescuers had used to reach the three victims 
 
 The area where they died is known for a type of quicksand, where the ground is prone to crumbling. 
 
 When the boy went into the quicksand, his father tried to help him and fell into the pit. His mother went to their aid and all three are thought to have become trapped and lost consciousness because of poisonous gases. The local civil protection department said that inside the pit was boiling hot mud. 
 
 Firefighters managed to recover the three bodies and Pozzuoli mayor Vincenzo Figliolia said he had never come across such a tragedy at the site in 40 years. 
 
 Image copyright EPA Image caption Solfatara is one of many volcanic craters in the Campi Flegrei area west of Naples 
 
 The surviving son was taken to a bar close to the entrance, where owner Armando Guerriero told La Repubblica: "We tried to calm him down, as he was obviously very shocked. He was repeatedly asking for the rest of his family." 
 
 The seven-year-old was later looked after by social workers and a psychologist. He was due to be reunited with his grandparents later. 
 
 A local worker at the site, Diego Vitagliano, said the accident was the worst thing he had seen in his life.
– An Italian supervolcano could be heading toward an eruption—and that's bad news for the 500,000 or so people who live in and around it, the Washington Post reports. Campi Flegrei is a 7.5-mile-wide caldera, the collapsed top of an ancient volcano. The eruption that formed it 39,000 years ago was the biggest in Europe in 200,000 years and may have been responsible for killing off the Neanderthals. Since then, it's only had two major eruptions: 35,000 years ago and 12,000 years ago, according to Science Alert. But a "minor" eruption in 1538 was still plenty serious, releasing enough material to form a new mountain. An Italian philosopher of the time described that eruption thusly: "At the second hour of the night, this mount of earth opened like a mouth, with a great roaring, vomiting much fire and pumice and stones.” Now activity is picking up at Campi Flegrei. Uplift started in 2005, and an alert level for the volcano was raised in 2012, requiring seismic monitoring, AFP reports. Recent years have seen increases in minor seismic activity and ground deformation. On Tuesday, researchers published a study in Nature stating that the caldera is nearing a "critical degassing pressure" that "can drive volcanic unrest toward a critical state." It's still impossible to say when another eruption may occur, but researchers are hoping to spur more research and monitoring at Campi Flegrei for the sake of the residents of nearby Naples, for whom an eruption "would be very dangerous." (Meanwhile, the biggest volcano on Earth may be waking up.)