Scientists discover "megabeds" at the bottom of the Mediterranean Sea, revealing a cycle of catastrophic supervolcano eruptions that occur every 10,000 to 15,000 years. The beds, located near the coast of Italy, are made of volcanic material and were formed by eruptions from the Campi Flegrei supervolcano. Refining eruption dates will provide a better understanding of the future risk posed by volcanoes in the region.