Nearly 20,000 ancient volcanoes discovered on the ocean floor: ScienceAlert

less than a quarter The entire ocean floor has been mapped on land, leaving gaps in our understanding of the underwater world.

Accidents await in the void: Undiscovered seamounts – ancient mountains formed by volcanic activity – can rise thousands of meters in the dark, endangering unsuspecting submariners.

Led by geoscientist Julie Gevorgian of the Scripps Institution of Oceanography in California, a team of scientists has just discovered more than 19,000 new seamounts using a new set of satellite data.

Finding so many underwater peaks under the sea is “incredible to think about,” Gevorgian Tell Newsweek.

“Especially when you realize how big these seamounts are and how they were previously unknown.”

As a result of volcanic activity deep below the ocean’s surface, seamounts can rise to about 3 to 10 kilometers (6.2 miles). They tend to be easily detected by sonar, but only if a ship passes over them.

Small undersea seamounts less than two kilometers high are hard to find, although they tend to form near mid-ocean ridges where magma rushes through the Earth’s thin, fractured crust.

In the past decade or so, scientists have turned to satellite data to detect small bumps in the ocean’s surface and map where seamounts are.

where Sonar uses sound waves By bouncing off the sea floor to map its contours, satellite altimetry does so indirectly, measuring subtle changes in sea surface height that reflect the gravitational pull coming from ridges in Earth’s submerged crust. The larger the mound, the stronger its gravitational pull on the seawater at the top.

Using this method, Gevorgian and his colleagues identified 19,325 new undersea volcanoes, adding to the 24,643 mapped seamounts that two of the team members had. It was previously indexed in 2011 And settle some errors in the process.

That brings the total to 43,454 mountains under the sea, nearly twice the number we know.

Many of the newly discovered seamounts are on the smaller side, thought to be too young to be detected in satellite data. However, recent developments to expand coverage and improve the accuracy of satellite data from the European Space Agency’s CryoSat-2 satellite and Saralcopy Indian and French space agencies, changed the picture.

Of the 700 strange peaks Gevorgyan and his colleagues discovered in areas of particularly good coverage, the smallest volcano was just 421 meters high, a rather small nodule as far as volcanism is concerned on the rugged sea floor.

Most of them were longer than 700 meters, and some were as high as 2,500 meters above the sea floor. Using these well-surveyed volcanoes as a guide, the researchers then estimated the shape and size of the other pillars they identified.

Researchers not involved in the work Tell the results It could deepen our understanding of plate tectonics, volcanism, the movements of ocean currents and marine life, in vast regions of the ocean that haven’t been mapped for a long time.

Channeling nutrient-rich waters from deep within, seamounts are a haven for marine life that traverses desert-like oceans. Its steep slopes also interfere with ocean currents that move heat around the globe. Buried in their geology, researchers expect to find evidence of plate tectonics and magma, along with precious rare-earth minerals.

“Because seamounts influence oceans and ecosystems, they are important features for study, mapping, and classification,” Gevorgian and colleagues. He writes in their published paper.

Despite this massive update of the number of known seamounts, researchers believe there may be thousands more waiting to be uncovered. In 2011, they estimated that it could be there As many as 55,000 peaks under the sea globally – A number that may need to be revised based on the new numbers.

“Our study certainly helped advance the global seamount catalog, but improvements in data accuracy could help us find more,” Gevorgian said. Tell Newsweek.

missions Already underway to help make this happen, but spotting smaller seamounts isn’t easy: They can be obscured by ocean sediment piling up on top of them, or by nearby seafloor features and turbulent ocean currents that might cause subtle gravitational differences that satellites are designed to pick up.

The study has been published in Earth and space sciences.