These huge megabeds from ancient supervolcano eruptions were hiding at the bottom of the sea between Naples and Sicily, researchers have found. Their discovery points to a cycle of catastrophic events that appear to hit the region every 10,000 to 15,000 years.
The researchers found the megabeds while investigating deposits at the bottom of the Tyrrhenian Sea, near the coast of Italy, close to Marsili, a known 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, explained lead study author Derek Sawyer, associate professor of Earth sciences at The Ohio State University.
In a new study, Sawyer and colleagues went back to the site to create higher-resolution images of the layers of sediment and discovered a succession of four megabeds, each between 10 to 25 meters thick, and each separated by distinct layers of sediments[1]. 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. Thus, the eruptions occurred roughly every 10,000 to 15,000 years.
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 quite active recently.
The oldest megabed formed after a huge eruption from Campi Flegrei ('burning fields'), situated to the west of Naples, around 39,000 years ago — one of the biggest known eruptions on Earth. The same eruption may also have created the second bed, as the layer between the two is just 1 meter — indicating a relatively short interval between the two events.
The scientists think the 18,000-year-old megabed formed in the wake of the Neapolitan Yellow Tuff supereruption of Campi Flegrei about 15,000 years ago, while the youngest megabed was deposited by another, less energetic eruption at Campi Flegrei.
The findings, Sawyer said, will help researchers understand the risk posed by volcanoes in the region. "That whole field is still active, there's still a lot of concern about the future of that, so it's certainly potentially possible that it could happen again," he said.
[1] Sawyer et al: 50,000 yr of recurrent volcaniclastic megabed deposition in the Marsili Basin, Tyrrhenian Sea in Geology - 2023. See here.
Geen opmerkingen:
Een reactie posten