Deep Carbon Degassing Measurements Help Explain Unrest at Campi Flegrei

Volcanoes are enigmatic and largely unpredictable. As they become more active, scientists track underground phenomena using a variety of measurements.

Increases in seismic activity and ground deformation often indicate impending volcanic eruptions. Work from DCO’s DECADE (Deep Earth Carbon Degassing) initiative suggests measuring volcanic gas emissions is also a powerful way of understanding the mechanisms driving changes in volcanic activity.

Over the last ten years, ground uplift at Campi Flegrei, an enormous caldera in Italy, resulted in intense scientific scrutiny of this reawakening volcano. DECADE’s Giovanni Chiodini (Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy) and colleagues began collecting gas samples from Solfatara, an active fumarolic field within the 12km-wide caldera, to analyze the deep processes potentially controlling new activity. In a paper published recently in Nature Communications, Chiodini et al lay out a model for magma degassing and decompression, which could explain the ongoing Campi Flegrei unrest [1].

“In general, unfortunately, volcanology is not a precise science,” Chiodini told Sarah Kaplan of the Washington Post. “We have many uncertainties and long-term predictions 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.”

In the current work, Chiodini and colleagues present a model for unrest at Campi Flegrei, which perhaps could be applied to other large calderas, in which magmas reach a so-called critical degassing point (CDP). At the CDP, magmas transport more heat and release water. This results in an injection of heated fluids into the overlying hydrothermal system, driving seismic unrest, and ground deformation.

Reaching the CDP does not necessarily mean a volcano will erupt. The authors note that magmas can cycle in and out of CDP.  Nonetheless, monitoring gas emissions remains a crucial tool in tracking volcanic unrest, helping to build an arsenal to enhance prediction of when and if eruptions may occur.

“Chiodini and his colleagues bring novel information on the mechanisms and rates of magmatic carbon (and water) transport at quiescent calderas – a key question of the DECADE program,” says co-investigator Alessandro Aiuppa. The supply of magmatic carbon to, and release from, active calderas is anything but constant, as magma injection and degassing into the upper crust (that triggers volcanic unrest) is episodic by nature. DECADE’s long-term volcanic gas observations are shedding new light into caldera-related contributions to the global volcanic carbon flux”. 

 

Images: Campi Flegrei, Italy. Credit Katie Pratt. 

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