In an effort to change this, scientists have created the most detailed view of the Earth’s seafloor to date, revealing huge mountains and giant crevices beneath the ocean.
The map was created by measuring the shape and gravity field of Earth, a relatively-new discipline known as geodesy. It provides gives an accurate picture of seafloor topography at a scale of 3.1 miles (5km) per pixel.
This map shows a global view of gravity changes. Shades of orange and red represent areas where seafloor gravity is stronger than the global average, a phenomenon that mostly coincides with the location of underwater ridges, seamounts, and the edges of Earth’s tectonic plates. Shades of blue represent areas of lower gravity, corresponding largely with the deepest troughs in the ocean
The maps were created through computer analysis and modeling of new satellite data from CryoSat-2 and Jason-1.
CryoSat-2 was designed to collect data over Earth’s polar regions, but it also collected measurements over the oceans.
Jason-1 was designed to measure the height of the oceans, but it had to be adjusted to a slightly different orbit in order to acquire the data needed to see gravity anomalies.
Seafloor features have a lot of mass, so they exert a gravitational pull on the water above and around them; essentially, seamounts pull more water toward their center of mass.
This causes water to pile up in small but measurable bumps on the sea surface. The new measurements of these tiny bumps were compared and combined with previous gravity measurements to create the map.
Close to 70 per cent of our planet is covered by water, and that water refracts, absorbs, and reflects light so well that it can only penetrate a few tens to hundreds of meters.
To humans and most satellite eyes, the deep ocean is opaque. But there are ways to visualise what the planet looks like beneath that watery shroud.
Sonar-based instruments mounted on ships can distinguish the shape of the seafloor. But such maps can only be made for places where ships and sonar pass frequently.
The majority of such measurements have been made along the major shipping routes of the world, interspersed with results from scientific expeditions over the past two centuries.
About 5 to 15 per cent of the global ocean floor has been mapped in this way, depending on how you define ‘mapped.’
David Sandwell of the Scripps Institution of Oceanography and Walter Smith of the National Oceanic and Atmospheric Administration have spent much of the past 25 years negotiating with military agencies and satellite operators to allow them acquire or gain access to measurements of the Earth’s gravity field and sea surface heights.
The result of their collaborative efforts is a global data set that tells where the ridges and valleys are by showing where the planet’s gravity field varies.
The map above shows a global view of gravity anomalies, as measured and assembled by Sandwell, Smith, and his team.
Shades of orange and red represent areas where seafloor gravity is stronger than the global average, a phenomenon that mostly coincides with the location of underwater ridges, seamounts, and the edges of Earth’s tectonic plates.
Shades of blue represent areas of lower gravity, corresponding largely with the deepest troughs in the ocean.
The maps were created through computer analysis and modeling of new satellite data from the European Space Agency’s CryoSat-2 and from the Nasa-CNES Jason-1, as well as older data from missions flown in the 1980s and 90s.