A supervolcano on the Italian coast has been stirring five centuries after its last eruption, Italian scientists report in a study of magma movements and hydrothermal unrest at Campi Flegrei published this week. But in contrast to the flurry of reports in the press, the Italians' model only predicts eruption, if at all, decades down the line. The unrest noted in the volcano's behavior starting in 2005 could also subside, stresses volcanologist Prof. Oded Navon of the Hebrew University of Jerusalem.
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"If it does erupt, it certainly could be a very serious matter. Vesuvius looks big and threatening, but when it comes to causing significant damage, Campi Flegrei is much more serious," Navon told Haaretz. "It isn't a volcano, it's a supervolcano."
Israel at least would likely be spared the worst of any ensuing tsunamis, being geographically protected by Italy, Libya and Sicily.
The Campi Flegrei system's latest rumblings began in 2005, since when it has been erratically showing signs of magma rising and intensifying hydrothermal activity. The rising ground level and other signs led the Italian authorities to upgrade the alert on the volcano in 2012 from green (nothing happening) to yellow (actively monitored). But how intense an eruption might be, if any, is uncertain, explains the Italian team in Nature, which sought parallels between the volcano's behavior today and going back about 2,000 years, but especially before the last time it blew, in the year 1538.
"The eruption 500 years ago from Campi Flegrei was fairly small," Navon points out. Like an ordinary volcano, a supervolcano can have a piddling little eruption that releases pent-up energy but causes little damage, he notes.
Civilization has known massive eruptions, recent notables include Indonesia's Mt. Tambora, Mt. Saint Helens in the U.S. and Pinatubo in the Philippines, and the unpronounceable Eyjafjallajökull in Iceland which, in 2010, erupted rather mildly, but pumped out enough ash to frustrate air traffic in the northern hemisphere for weeks. But although an impressive blast by Santorini some 5,000 years ago destroyed Minoan culture in Crete, and Vesuvius destroyed Pompeii, modern civilization has never experienced a supervolcano blow. We have only seen the evidence of supervolcanic blasts from prehistory.
"Campi Flegrei is a lot bigger than what we're used to in human history," says Navon. "This is another order of magnitude." If Campi Flegrei erupts and it is not small, not only the roughly three million people living in nearby Naples and the vicinity would be in danger.
Campi Flegrei is young, it and its 12-kilometer caldera having formed about 39,000 years ago. Yellowstone, another famous and older supervolcano that's been darkly simmering forever, is yet another order of magnitude bigger than Campi Flegrei.
But in its formation, the Italian caldera produced the largest eruption Europe had experienced for 200,000 years. If it erupts again, it could produce hundreds of cubic kilometers of magma, covering wide swathes of southern Italy. It could belch out enough ash to change global weather, says Navon, noting that following Pinatubo came one of the rainiest winters ever – and this would be much, much bigger.
Depending on wind direction, all the nations around, including Greece and Serbia and Romania but possibly as far north as the Ukraine, could be blanketed in ash. And given that part of the volcanic system is underwater, the probability of tsunami is high.
Volcanoes are so fickle
So, how likely is it to blow? Volcanologists can warn that a crisis is possible, but cannot predict what will happen years from now. That said, the Italians created a theoretical model to characterize the behavior of the volcano and hydrothermal influences.
Navon points out that the parameters are many and myriad, with some pointing in one direction (in favor of eruption) and some against. The release of hot water through hydrothermal vents argues against eruption; the deforming ground argues in favor, for instance.
The scientists themselves, headed by Mauro Di Vito, warn that (over decades) the magma at Campi Flegrei could be progressing toward a critical stage. They applied their model to historic eruptions in New Guinea and the Galapagos, and found it may explain what happened there, when unrest led to eruption.
"At Campi, they see unrest if they are right in all three cases and if the model is right, we could be advancing towards an eruption of Campi, not tomorrow but in a time frame of some decades," Navon sums up.
Or nothing could happen. Campi Flegrei could subside. It did just that in 1983-1984: there was unrest, then there were quakes and then, nada.
"For instance, the exit of water can lead magma to crystallize and become more viscous, which acts against eruption. We are not saying the volcano is on route to erupt. We are saying it's worthy of notice," Navon explains. Also, no special quake activity has been measured this time around.
One day, though, one year, it will blow. While Israel isn't far away, in fact its coasts should be largely protected from any tsunami by geography, Navon points out: Campi Flegrei is on the west coast of Italy and France and Sardinia, and northern Italy, are in more danger.
The ash is another story. Campi Flegrei may be no Yellowstone but it could produce a climatic trouble that lasts a few years. While the ash sinks quite fast, Navon says, toxic gases can remain in the atmosphere for over a year.
"These things happen every tens of thousands of years and it's not clear we are going there," Navon says. "But humanity should prepare and think what to do in such cases. If Yellowstone wipes out American crops, it's a problem for the whole world, which can definitely lead to chain reactions, leading to mass migrations and starvation. Ultimately it can bring down civilization. How rare is it? It's more common than a meteorite hitting us. As for Campi Flegrei, if its ash cloud reaches Romania or Ukraine, it will suffocate the Eastern Europe bread basket. And then it's hard to say what people will do."