A new seafloor map shows thousands of new mountains

The new seafloor map (Image courtesy Scripps Institution of Oceanography. All rights reserved)
The new seafloor map (Image courtesy Scripps Institution of Oceanography. All rights reserved)

A research published in the journal “Science” has shown a very accurate map of the world’s seafloor that includes thousands of previously unknown underwater mountains. The researchers, led by David Sandwell of the Scripps Institution of Oceanography, conducted this study using satellite data collected over the past years.

Today we can look at comprehensive maps of the Moon and even Mars, on the contrary we have maps covering perhaps 10% of the oceans floor. Salty water is opaque to the techniques used to map the mountains on the mainland and the use of ecosonar installed on ships requires a huge effort to get the job done.

This problem was addressed in a different way using the instruments of some satellites, notably the ESA’s CryoSat and Jason 1, a collaboration mission of NASA and CNES, the French space agency. They are two satellites designed to map respectively oceans and polar ice caps. Both are equipped with radar that detected data are also useful for mapping the seafloor.

The characteristics of the ocean surface are also determined by the ones existing on the bottom. There are ridges and valleys on the surface reflecting on a much smaller scale those at the bottom. The slight increase in gravity caused by masses of rock that form underwater mountains attracts water over them. These features can be detected by radar altimeters from space.

The Cryosat satellite – though actually it’s Cryosat-2 because the first one was destroyed following a problem with the rocket – was launched on April 8, 2010. Its SIRAL (SAR / Interferometric Radar Altimeter) instrument works in its most advanced mode on icy surfaces but is always active. This radar altimeter keeps on working when the satellite is over the oceans providing useful information for research such as the one published in “Science”.

The Jason-1 satellite was launched on December 7, 2001 as the successor of the TOPEX/Poseidon mission, a previous collaboration between NASA and CNES to map the topography of the oceans surface. Its mission officially ended on July 3, 2013 after its last transmitter failed. It, too, was equipped with a radar altimeter which provided a huge amount of data on the oceans topography.

The new map created thanks to this research will also improve Google maps but will also have important uses. It’s much more accurate than the best one previously existing and allowed to discover new ridges. The geological plates shatters near them due to magma coming out of the mantle. It’s the continental drift, also related to volcanic and seismic activity. Learning more about the seafloor will allow a better understanding of these destructive phenomena.

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