PLANET EARTH
Huge ‘megabeds’ from ancient supervolcano eruptions are hiding at the bottom of the Mediterranean Sea. Their discovery points to a cycle of catastrophic events that appear to hit the region every 10,000 to 15,000 years. Megabeds are huge sub-marine deposits that form in marine basins as a result of catastrophic events like volcanic eruptions. The researchers found the beds while investigating deposits at the bottom of the Tyrrhenian Sea, near the coast of Italy, close to a large underwater volcano. Previous research into geohazards in the area using sediment cores and imaging indicated something was hidden beneath the ocean, but the resolution was not high enough to see the megabeds.
In a new study, Derek Sawyer, associate professor of Earth sciences at Ohio State University, and colleagues went back to the site to create higher resolution images of the layers of sediment, discovering a succession of four megabeds, each between 10 and 25 metres thick and each separated by distinct layers of sediments. Cores drilled from the site showed the megabeds were made of volcanic material. The oldest layer was around 40,000 years old, the next oldest was 32,000 years, the third 18,000 years, while the youngest formed about 8,000 years ago.
The team then looked at known volcanic activity in the region to determine the source of the megabeds. The region where the beds formed is extremely active volcanically and includes the Campi Flegrei supervolcano, which has been rumbling recently. The oldest megabed formed after a huge eruption from Campi Flegrei
