Satellites are revealing a treasure trove of previously-unknown features at the bottom of oceans and seas around the world. A new map of the Indian Ocean was charted, examining gravity fluctuations in the underwater bed. This unique method of mapping the seafloor allows researchers to discover a wide range of previously-hidden geological features, including thousands of extinct volcanoes.

Geologists were able to gather information from the satellite data, allowing them to answer long-held questions about the formation of the planet. Roughly 90 percent of the deep-sea ocean floor remains unmapped; leading oceanographers to state that Mars is better understood than these regions on Earth.

Malaysia Airlines flight 370 went missing in March, and is presumed to have crashed in the Indian Ocean, although wreckage has not yet been found from the aircraft. This incident has highlighted the lack of detail known about much of the underwater terrain.

Maps of the ocean floor are traditionally developed using multibeam sonar systems, carried on ships. As these vessels cross the water, the devices recorded depths to the ocean floor. The sonars can only map directly beneath the boats, leaving large gaps in the recordings.

Satellites flying high above the Earth are able to measure swellings and depressions on the surface of the water, in a process called sea-surface topography. Once corrected for waves and tides, these features reveal the presence of volcanoes, mountains and other massive features under the water.

The Geosat observatory was launched in 1985, followed by the Geosat Follow-on mission in 1998. Data about the seafloor from these vehicles was combined with readings from the ERS-1 spacecraft, managed by the European Space Agency (ESA), providing researchers with most of the data on the seafloor available until now. These observatories have recently been joined in space by NASA's Jason-1 spacecraft, as well as the CyroSat-2, launched by the ESA to study polar ice caps. The additional observatories were able to examine features under the ocean, including details of ridges and faults previously hidden by sediment.

An extinct ocean ridge, 500 miles long, was discovered under the southern Atlantic Ocean. This feature was formed after North America began to drift away from Africa, but is no longer spreading, according to geologists. Another similar ridge, which formed the Gulf of Mexico, was also found off the coast of North America. Researchers had long suspected the waterway was formed by the spreading of such a feature, but this is the first time it has been identified.

"This work brings home the importance of collecting new data, as well as applying expert processing to older data - squeezing out more information than was thought possible," Paul Wessel, geophysicist at the University of Hawaii, said.

As detailed as the new gravity map is, the resolution is still far too low to locate the missing jet.