(Image credit: @Didier Marti/Getty Images)
Several relatively young underwater volcanoes have been discovered beneath the surface of the Pacific Ocean, some of which may be active.
The volcanoes were discovered during an expedition to map the seafloor in the Cook Islands, about 2,900 miles (4,700 kilometers) south of Hawaii. If the geological features are indeed active, the heat they release could create a unique and interesting marine ecosystem in the area, the researchers say.
“We have not seen any obvious signs of volcanic activity so far, but on the other hand, no one has had the opportunity to thoroughly survey the seabed and take samples,” said officials from the Seabed Minerals Authority (SBMA), which led the study. “Once processed and interpreted, our new seabed map will help future scientists quickly identify the most promising locations for sampling.”
The Cook Islands are a group of 15 islands in the South Pacific Ocean, located between French Polynesia and American Samoa. The archipelago was formed millions of years ago when the Pacific Plate moved over a magma hotspot in the Earth’s mantle, similar to how the Hawaiian Islands were formed. A magma hotspot is an area in the Earth’s mantle where abnormally hot rock rises to the surface, causing volcanic activity. Unlike volcanoes, which form at tectonic plate boundaries, hotspots occur within plates and remain in place while the plate above them moves over time.
New bathymetry plot of the volcanic chain south-southeast of Rarotonga. The top map also compares new low-resolution satellite bathymetry data.
The hot mantle plume from the hot spot carries heat and magma to the crust, which can cause the magma to erupt onto the seafloor and rapidly cool in the water. Over time, repeated eruptions create a volcanic structure, forming an underwater volcano. If eruptions continue, the volcano can grow so large that it breaks through to the ocean surface, forming a volcanic island.
Most of the volcanoes in the Cook Islands are ancient, with rocks dating back tens or even hundreds of millions of years. However, Rarotonga and Aitutaki are made up of a mix of older and newer rocks, as they are among the youngest islands to form above a hotspot – the youngest rock on Rarotonga is 100,000 years old.
Sourse: www.livescience.com
