Researchers Uncover Massive Underwater Sea Mountains

Jasmin Wu/UCSD Guardian

Researchers at the Scripps Institution of Oceanography discovered colossal uncharted mountains underneath the waters of the South Atlantic Ocean while exploring the seafloors.

Many of these mountains, called seamounts, are previously unexplored. The largest one rises 14,700 feet from the sea floor, making it taller than California’s tallest point, Mount Whitney. According to geophysics professor David Sandwell, the newly discovered seamounts are inactive volcanoes that can affect plate tectonics, ocean climate and underwater organisms. For example, a large current deflected by the seamount could change the direction and climate of the ocean.

“If you have a big current and it hits a volcano, it can be deflected to a different direction which could change the climate,” Sandwell said. “If a warm current hits a seamount and changes direction, it could create a warmer climate.”

Understanding the location and size of the seamounts gives information about the plates and mantle from which it formed.

“They are a special kind of seamount which were once at sea level [but that got eroded] flat through millions of years, subsided and got deeper, about 500 meters below sea level,” Sandwell said.

The mountains were charted out for the first time by scientists — led by Captain Chris Curl and geophysicist J.J. Becker —aboard Scripps research vessel the R/V Melville. The crew navigated through the underwater mountains from Feb. 20 to March 14.

The discovery was an accident. While exploring unknown underwater features in a different location in the South Atlantic, the vessel was forced to take an alternative route after poor weather made navigating in the South Atlantic difficult. Researchers then found the large underwater mountains.

“This was an uncharted area of the sea,” Sandwell said. “It’s very remote and it takes about four days of ship time to get to that location.”

Sandwell — who guided researchers aboard the Melville from South Africa to Chile while he remained in La Jolla — then charted the mountains and mapped the sea floor to observe plate tectonics and underwater fault lines.

“[We wanted] to chart these undersea volcanoes to know something about geology of ocean basis,” Sandwell said. “Like plate tectonics, if you could map sea floors completely, you could know all about plate tectonics.”

The researchers used a multibeam echo sounder to measures distances by transmitting sound waves and analyzing the return echo that bounced back from the seafloor and seamounts. Curl watched the device to make sure they were not too close to the seamounts and in danger of running aground.

The team found about six seamounts, which were about 300 to 600 meters above the seafloor, which is usually about 5,000 meters deep. Researchers also found faults on the seafloor that are about the same size as the San Andreas Fault.

The Melville’s current expedition includes analyzing the ocean floor of Valparaiso, Chile, to determine how the 8.8-magnitude earthquake that occurred in February 2010 changed the Earth’s crust. This information will be used to determine how earthquakes cause deformations in the sea floor.

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