Italy's Campi Flegrei volcano may have had a more explosive history than experts thought.
A new study finds that the volcano — or one near it — laid down an enormous layer of ash and volcanic rock about 109,000 years ago. This outburst, dubbed the Maddaloni/X-6 eruption, was similar in size to the biggest known Campi Flegrei eruption, which happened 40,000 years ago and was so large that it created a caldera 9 miles (15 kilometers) in diameter.
