An Ocean of Mountains

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The ocean comprises a significant portion of the Earth yet it remains a field we know the least about. Humans know more about the topography of Mars than we do about the ocean floor, and our poor knowledge of seabed topography is demonstrated by the ongoing search for missing Malaysia Airline jet MH370. Scientists and researchers, however, are trying to decrease that knowledge gap a little more. With the help of satellite technology, a team of American and European researchers recently announced that they have discovered thousands of new mountains on the ocean floor.

Up until now, there have been significant obstacles to mapping the locations of mountains on the seabed, known as seamounts. First of all, saltwater is opaque so that eliminates the possibility of using the same techniques used to map mountains on land. There have been other attempts to use echosounders on ships, instruments used to gather high-resolution data by bouncing sound off the sea floor. However, this method is expensive and time-consuming. Consequently, only 10% of the oceans have been surveying in this way.

As an alternative, scientists have turned to satellites more and more to help increase our knowledge of the ocean floor and what it looks like. Satellites using radar altimetry are able to confer the shape of the ocean bottom from the shape of the water surface above. The pull of gravity means that water is drawn into highs above tall seamounts and slumps into depressions over deep sea trenches. Using technology from the Jason 1 and CryoSat spacecraft, scientists were able to gather new, improved datasets.

The results may show thousands of new seamounts, all of which are at least 1.5 km (approximately 1 mile) high. Previous datasets only displayed about 5,000 seamounts that were taller than 2 km (1.2 miles) high. This new dataset could potentially mean the discovery of another 25,000 seamounts. The research has already led to important discoveries in the ocean floor like the presence of an extinct ridge in the Gulf of Mexico and two halves of a different ridge in the South Atlantic that became separate when Africa pulled away from South America.

In the end, more research is needed to be done. Knowledge of the locations of seamounts could play a critical role in management and conservation of the ocean’s resources as well as better awareness of how the oceans conduct heat and influence the climate. It could open up a whole new world to those who study the movement of Earth’s continents. Nevertheless, much progress needs to be done in funding an entire satellite mission dedicated to mapping the ocean floor and finding the political will to do so.

Map of the North Atlantic Ocean showing gravity anomalies. Marine gravity model of the North Atlantic (10 mGal contours). Red dots show locations of earthquakes with magnitude > 5.5 and they highlight the present-day location of the seafloor spreading ridges and transform faults. This gravity information shows the details of the plate tectonic history of the rifting of these continents including the subtle signatures of fracture zones that are currently buried by sediment.
Marine gravity model of the North Atlantic (10 mGal contours). Red dots show locations of earthquakes with magnitude > 5.5 and they highlight the present-day location of the seafloor spreading ridges and transform faults. This gravity information shows the details of the plate tectonic history of the rifting of these continents including the subtle signatures of fracture zones that are currently buried by sediment.

References

Dempsey Morais, Caitlin. “New Detailed Map of the Ocean Floor” GIS Lounge. 6 Oct. 2014. Web. 06 Oct. 2014. <http://www.gislounge.com/new-detailed-map-ocean-floor/>.


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“Exploring Ocean Tectonics from Space.” Marine Gravity from Satellite Altimetry. N.p., n.d. Web. 06 Oct. 2014. <http://topex.ucsd.edu/grav_outreach/>.

Sandwell, D. T., R. D. Müller, W. H. F. Smith, E. Garcia, R. Francis, New global marine gravity model from CryoSat-2 and Jason-1 reveals buried tectonic structure, Science, Vol. 346, no. 6205, pp. 65-67, doi: 10.1126/science.1258213, 2014.

“New Map Exposes Previously Unseen Details of Seafloor.” Scripps Institution of Oceanography, UC San Diego |. N.p., 2 Oct. 2014. Web. 06 Oct. 2014. <https://scripps.ucsd.edu/news/new-map-exposes-previously-unseen-details-seafloor>.

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