Three giant pockmarks – crater-like structures on the seabed – found by the team are possibly twice the size of the largest pockmarks ever recorded.
Scientists believe they are the ancient remnants of vigorous degassing from under the seafloor into the ocean. The structures (the largest being 6.8 miles by 3.7 miles in diameter and 328 feet deep) are at water depths of about 0.6 miles and there is currently no sign of gas being emitted from them.
The team investigated the larger seafloor structures on the German research ship Sonne. Their aim was to determine the geological origin of the structures, which were first noted in 2007.
“Some of the pockmarks are huge compared to similar structures observed elsewhere in the world,” Dr Davy said. “It’s most unusual for scientists to encounter seafloor structures of this size and complexity. They are big enough to enclose the Wellington city urban area, or lower Manhattan.”
The geological processes that led to the formation of the larger structures were still unclear.