The scientists uncovered what they are calling "seafloor storms" 10,000 feet dee
While most people equate the ocean depths with peacefulness,
scientists have discovered masses of water in motion thousands of
Rough storms like the one savaging this Swedish passenger ferry in
1999 have been found to occur deep underwater.
The scientists uncovered what they are calling "seafloor storms"
10,000 feet deep in the Gulf of Mexico. These storms are powerful
enough to carve furrows into the seafloor and whisk away animals and
The researchers are working to determine what causes the storms and
what implications they might have.
For example, the presence of these storms raises concerns for the
builders of oil and gas wells in the region, said Ian MacDonald of
Texas A&M University.
The storms were discovered while researchers were conducting dives in
the deep-sea submersible Alvin. Scientists had suspected their
existence but had never confirmed them, MacDonald said.
Unlike wind storms on land, the water movement was horizontal, not up
and down, he said. The mass of moving water was 2,000 feet thick and
the storm lasted for the length of a six-hour dive, he said. "We got
to witness that first-hand."
When researchers descended into a region about 180 miles south of the
Louisiana coast, the submersible was caught in the current.
"The sediments were stirred up by it. They saw fish and shrimp being
whipped along like in a river ... animal life was being swept away,"
"That's an enormous force," he said.
He added that the water movement in the area where the storm was
viewed had channeled the seafloor into miles-long gullies. Previous
readings from sonar had caused the scientists to suspect the storms
The gullies "reminded me of the buttes and mesas in the Southwest,"
Along the edge of the continental shelf, where the sea floor plunges
to depths of 8,000 to 10,000 feet, the masses of water researchers
encountered were nearly 2,000 feet thick and moving at 1 to 1.5
knots, MacDonald said. A knot is 1.15 miles per hour.
While that sounds slow, normal water movement in the deep oceans is
less than one-tenth of a knot. This relatively fast-moving water
presses against anything in its path with a great force.
William R. Bryant, a Texas A&M geologic oceanographer, was aboard
Alvin during one dive into what he preferred to call a powerful
current rather than a storm.
But, he confirmed, "it was first time anyone had ever been in" one of
Currents had been measured by instruments before and the powerful
ones were suspected because of the shape of the seafloor, said
Bryant, who was swept along in a 1.5 knot current and believes some
reach more than 2.5 knots.
"Those are exceptional, high currents," he said. "We see large
geological features, furrows, that are the result of these currents."
Bryant said the currents are a "constraint" rather than a hazard to
oil and gas rigs.
The current is sufficient to undermine pipelines on the seafloor, he
said, so oil and gas developers will have to determine the maximum
speed of likely currents and create designs to cope with them.
The expedition, which departed from Galveston, Texas on Oct. 16, was
Alvin's first to the Gulf in eight years. It is operated by Woods
Hole Oceanographic Institution.
The National Oceanic and Atmospheric Administration sponsored the
expedition through its National Undersea Research Program Center at
the University of North Carolina at Wilmington.
Besides Texas A&M, other organizations participating included
Louisiana State University, University of South Carolina, College of
William and Mary and the Department of Energy