Scientists have come up with a new seafloor map using satellite data, unraveling the secrets of the sea including those of the deepest and least explored areas of the Earth's ocean.
In an effort described in the journal Science on Oct. 3, David Sandwell, from the Scripps Institution of Oceanography in La Jolla, California, and colleagues, used measurements taken from high-resolution radar equipment onboard the CryoSat-2 satellite of the European Space Agency (ESA) and the Jason-1 satellite of the National Aeronautics and Space Administration (NASA) to create a seafloor map that features in an unprecedented detail the geological features of the world's oceans.
The researchers said that satellite's measurements of the pull of gravity allowed them to map the geological features of the sea floor. The CryoSat-2 and Jason-1 satellites, which were designed to track changes in sea level and have altimeters that can sense and measure gravity field, helped map the seafloor with their ability to detect dips and ripples in the surface of the ocean.
"The topography of the ocean surface mimics the rises and dips of the ocean floor due to the gravitational pull," ESA explained. "Areas of greater mass, such as underwater mountains, have a stronger pull, attracting more water and producing a minor increase in ocean-surface height."
Undersea mountains and ridges have mass large enough to produce a gravitational pull that causes sea levels to drop by up to 3.9 inches above them while fractures and rifts elevate sea surface levels because of the reduced gravitational attraction above them.
The gravitational measurements allowed the researchers to detect geological features that hide beneath layers of sands and sediments and piece together patterns of deviations producing a map that offers a glimpse of underwater tectonics. The new seafloor map reveals underwater ridges, rifts and trenches including a mid-ocean ridge in the Gulf of Mexico, whose length is comparable to the width of Texas, and a 500 mile-long ridge beneath the South Atlantic west of Angola that formed after the South American continent detached from Africa.
"We found an extinct spreading ridge in the Gulf of Mexico, a major propagating rift in the South Atlantic Ocean, abyssal hill fabric on slow-spreading ridges, and thousands of previously uncharted seamounts," the researchers wrote. "These discoveries allow us to understand regional tectonic processes and highlight the importance of satellite-derived gravity models as one of the primary tools for the investigation of remote ocean basins."
