Thursday, December 22, 2016

A supervolcano caused the largest eruption in European history. Now it’s stirring again.

[Washington Post] The Italian name for the caldera — Campi Flegrei, or “burning fields”— is apt. The 7.5-mile-wide cauldron is the collapsed top of an ancient volcano, formed when the magma within finally blew. Though half of it is obscured beneath the crystal blue waters of the Mediterranean, the other half is studded with cinder cones and calderas from smaller eruptions. And the whole area seethes with hydrothermal activity: Sulfuric acid spews from active fumaroles; geysers spout water and steam and 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 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. Read More