Best View Ever of Hidden Seafloor Revealed in New Images [Slide Show]
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SEEING SEAMOUNTS: At the bottom of the South China Sea, this image shows seamounts and atolls, along with the depths of water lying over them. Credit: COURTESY MINISTRY OF THE INTERIOR, TAIWAN
SHAKING AT THE BOTTOM: In the North Atlantic red dots show the location of magnitude 5.5 or higher earthquakes. They trace the sites of ridges and faults where the ocean floor is now spreading. Credit: Courtesy David Sandwell, Scripps Institution of Oceanography
MEETING AT THE JUNCTION: This image shows the Indian Ocean Triple Junction, where three major tectonic plates come together. Red dots highlight the collision zone, site of magnitude 5.5 and higher undersea quakes... Credit: Courtesy David Sandwell, Scripps Institution of Oceanography
SHAKING AT THE BOTTOM: This image of the Southwest Indian Ridge shows the slowest ocean spreading zone on the planet, and the site where the African and Antarctic continental plates started separating. Credit: Courtesy David Sandwell, Scripps Institution of Oceanography
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SEPARATING SOUTH AMERICA: This close-up of the southern portion of the Mid-Atlantic Ridge, highlighted by green dots that represent earthquakes along this feature, also shows the faults in the ocean floor perpendicular to the ridge... Credit: Courtesy David Sandwell, Scripps Institution of Oceanography
Eighty percent of the ocean floor, hidden deep below the waves, has not been mapped. It is out of the accurate range of surface sonar. But now a series of new maps have been produced, twice as precise as anything done before, and they reveal thousands of previously uncharted sea mountains as well as fractures at the ocean bottom that produce deep-sea earthquakes.
You can see some of the maps here. The images, published Thursday in Science, are the product of sensors on two satellites. The sensors, called altimeters, detect very small changes in ocean surface height. That surface bends down a bit over seamounts, for example, pulled by the gravity of the giant structures, and it mirrors their shapes. David Sandwell, a geophysicist at the Scripps Institution of Oceanography, and his colleagues used that phenomenon to produce these startlingly detailed charts of the deep, even features buried under mile-thick sediment layers. This newly charted topography will help scientists better understand how ocean waters circulate and mix, activity that strongly influences Earth’s climate. And it can add to their understanding of how continents formed early in the planet’s history, and why clusters of quakes occur in specific places now.
ABOUT THE AUTHOR(S)
Josh Fischman is a senior editor at Scientific American who covers medicine, biology and science policy. He has written and edited about science and health for Discover, Science, Earth, and U.S. News & World Report.Follow Josh Fischman on Twitter.