Scientists have discovered almost 20,000 underwater mountains on the deep seafloor by examining images of the ocean surface captured from space and looking for gravitational perturbations, reports a new study.
The research has nearly doubled the number of known “seamounts” from 24,643 to a total of 43,454, while also exposing fascinating details about the topography of the ocean floor and the vibrant ecosystems that thrive on submerged mountain slopes.
People have been fascinated by mountains since thousands of years. This has led to mythologies based around peaks such as Olympus and Everest. As land animals, we miss out on the entire world of mountains and slopes under the ocean, such as the largest mountain range known as the Mid-ocean Ridge.
Seamounts are active or extinct volcanoes that tower at least 3,300 feet above the ocean floor, which is about the same elevation as Mount Vesuvius in Italy. Sonar sensors aboard ships have helped to discover many of these mountains, but only about a fifth has been mapped using this method.
Now, scientists led by Julie Gevorgian, a researcher at the Scripps Institution of Oceanography at the University of California, San Diego, have used satellite observations to discover thousands of seamounts that were previously unknown.
With the space-down perspective, researchers could pinpoint the subtle changes on the surface of the ocean caused by hidden seamounts. The team used the technique “to update and refine a global seamount catalog, finding 19,325 new seamounts,” according to a recent study published in Earth and Space Science.
“The knowledge of the global distribution of seamounts is still incomplete because only 20% of the seafloor has been mapped by ships,” Gevorgian and her colleagues said in the study. “However, seamounts are valuable characteristics of the ocean floor since they provide insight on many of the Earth’s geological, oceanographical, and ecological cycles and processes.”
“From an ecological perspective, seamounts are centers for diverse biological communities,” the researchers added. “The ocean upwelling due to the presence of seamounts brings valuable nutrients from the deep water to the surface. They are therefore the perfect habitat for a wide range of marine flora, fauna and fish. Due to the impact that seamounts have on the ocean and ecosystems, they are important features to study, map, and classify.”
To that end, Gevorgian and her colleagues set out to probe the global oceans for signs of submerged seamounts with a new dataset of vertical gravity gradient (VGG) observations that measure the curvature of the ocean surface from space. A slew of recent satellite missions have dramatically improved the resolution and quality of VGG data, including the Indian-French mission SARAL, the American-French mission Jason-1, and the European missions CryoSat-2 and Envisat.
These new precision observations have opened a whole new view of mountainous seafloor regions. The researchers meticulously identified the new seamounts by eye, and even recategorized some of the existing mountains recorded in the Kim-Wessel catalog, a global database for seamounts.
These results expand our understanding of ocean summits and show the potential of satellites to explore uncharted waters.
“The addition of these new seamounts and refinement of previous picks updated the catalog to a total of 43,454 seamounts,” the team concluded in the study. “Prospective improvements in the VGG can further expand our knowledge of seamounts while surveying done by multibeam sonar remains limited.”
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