A new seafloor map shows gravity anomalies in the western Indian Ocean. Shades of orange and red represent areas where seafloor gravity is stronger (in milligals) than the global average, a phenomenon that mostly coincides with the location of underwater ridges, seamounts and the edges of Earth's tectonic plates. The darkest shades of blue represent areas with the lowest gravity, corresponding to the deepest troughs and trenches in the ocean. (Credit: NASA Earth Observatory maps by Joshua Stevens, using data from Sandwell, D. et al. (2014))
An international scientific team recently published a new map of the ocean floor based on Earth's gravity field to help submariners and ship captains with navigation, particularly in previously uncharted areas. The map also is expected to aid prospectors scouting for oil, gas and mineral resources.
The maps were created through computer analysis and modeling of new satellite data from the European Space Agency's CryoSat-2 and NASA-CNES Jason-1 as well as older data from missions flown in the 1980s and 1990s. David Sandwell of the Scripps Institution of Oceanography and his team derived the shape of the seafloor and its gravity field from altimetry measurements of the height of the sea surface; mountains and other seafloor features have a lot of mass, so they exert a gravitational pull on the water above, pulling more water toward their center of mass. The new map portrays seafloor features as narrow as five kilometers (three miles).
