Researchers from the University of Oxford has found that the origin of a prehistoric volcanic eruption that covered the Mediterranean region in ash 29,000 years ago was from a supervolcano in southern Italy.

Eruption Of Campi Flegrei Behind Widespread Volcanic Ash Layer

The eruption of Italy's Campi Flegrei 40,000 years ago is to date the largest known volcanic eruption that happened in Europe in the last 200,000 years.

Now, study researchers Paul Albert and colleagues confirmed that an ancient eruption that spread layers of volcanic ash across more than 150,000 square kilometers of the Mediterranean also came from Campi Flegrei.

Exposed deposits found around the source volcano often establish large volcanic eruptions, as deposits of large eruptions tend to form thick sequences.

Since the late 1970s, however, a widespread volcanic ash layer dating back from 29,000 years ago was commonly identified in marine and lake sediment cores from across the Mediterranean, suggesting of a large-scale eruption.

Despite the widespread distribution of the ash and their relatively young age, researchers could not find a clear evidence that would link of such an event to any of the main active volcanoes in the region.

Researchers now point at Campi Flegrei as the source of the eruption. Albert and colleagues conducted a chemical analysis of an eruption deposit found 5 kilometers northeast of Campi Flegrei caldera and found their composition is entirely consistent with the ash layer produced by the mysterious eruption.

This, along with new dating of the near-source eruption deposit, verified that an eruption of the Campi Flegrei was behind the widespread ash layer.

Masseria Del Monte Tuff

The researchers also used computer-based ash dispersal model to reconstruct the size of the volcanic eruption they call Masseria del Monte Tuff. They said its magnitude is comparable to the caldera forming eruption of the Campi Flegrei that occurred 15,000 years ago.

"The dispersal and thickness of the deposits associated with this eruption, herein named the Masseria del Monte Tuff, were simulated using a tephra sedimentation model," the researchers wrote in their study.

"This volume and the areal distribution suggest that the Masseria del Monte Tuff resulted from a magnitude (M) 6.6 eruption (corresponding to volcanic explosivity index [VEI] 6), similar to the 15 ka caldera-forming Neapolitan Yellow Tuff (M 6.8) eruption at Campi Flegrei."

The researchers reported their findings in a study published in the journal Geology on April 25.