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A new comprehensive map of Earth’s seafloor presented in the Oct. 3 Science is the most accurate global seafloor map ever made and could provide new clues to how Earth’s surface got its shape. Using data from satellites that measure variations in Earth’s gravitational field, researchers have found a new and more accurate way to map the sea floor.
“We know a lot about the continents, but we know almost nothing about what’s going on in the oceans,” says lead author David Sandwell, an earth scientist at the Scripps Institution of Oceanography in La Jolla, Calif. “It’s like being on another planet; the ocean is probably the most unexplored feature in the inner solar system.”
The map shows the mountains, or ‘seamounts,’ extending more than half a mile along the ocean bed. Lead researcher, geophysicist Professor David Sandwell from the University of California, San Diego, said: “The kinds of things you can see very clearly now are abyssal hills, which are the most common land form on the planet.”
In many parts of the ocean, including the region of the Indian Ocean where the Malaysian aircraft MH370 was lost this year, scientists don’t know much about seafloor tectonics. The problem is that saltwater is opaque to all the standard techniques that are used to map mountains on land.
Satellites fitted with altimeters send pulses to the ocean’s surface – which bulge outward and inward to mimic the topography of the ocean floor. The sensors then record the response, or gravity signal, which can reveal buried tectonic structures. To date, the number of available measurements has limited the resolution of these images.
The researchers said on Thursday they used gravity measurements of the seafloor from radar equipment aboard the European Space Agency’s CryoSat-2 satellite and NASA’s Jason-1 satellite to capture underwater geological features in unprecedented detail.
The new map reveals major seafloor and sub-seafloor structures, which include a mid-ocean ridge beneath the Gulf of Mexico with a length about equal to the width of Texas, as well as another ridge under the South Atlantic west of Angola about 500 miles long that was formed just after the continent of South America separated from Africa.
The roughness of the seafloor is important also as it steers currents and promotes mixing behaviours that are critical to understanding how the oceans transport heat and influence the climate.