Scientists Find Seafloor Storms in Ocean

W A S H I N G T O N, Nov. 2 -- Thousands of feet below the ocean’s surface, sudden powerful currents stir up sediments and sweep fish andshrimp along as though they were in a river, scientists havediscovered.

Past sonar readings and furrows on parts of the seafloor havehinted at these currents, called storms by some researchers.

Now they have finally been experienced, off the edge of thecontinental shelf in the Gulf of Mexico, some 8,000 to 10,000 feetdeep.

Witnessing the Storm

“Abyssal storms arise suddenly and sweep along the base of theescarpment. We got to witness that first hand,” Ian MacDonald ofTexas A&M University said Wednesday.

The powerful currents — seen by researchers during a two-weekexpedition involving several dives in the deep-sea submersibleAlvin — have carved furrows into the seafloor.

Scientists now are working to determine what causes the stormsand what implications they might have, particularly for deep seagas and oil wells now being developed in this region.

MacDonald said the storms are massive currents nearly 2,000 feetthick, moving at 1 to 1.5 knots. A knot is 1.15 miles per hour.

While that “doesn’t sound like much,” MacDonald said, normalwater movement in the deep oceans is less than one-tenth knot. Therelatively fast-moving water presses against anything in its pathwith a great force.

William R. Bryant, a Texas A&M geologic oceanographer, wasaboard Alvin during one dive into one of the powerful currents.

“It was first time anyone had ever been in” one of theseevents, he said.

A Concern for Pipelines

Currents had been detected by instruments before and powerfulones were suspected because of the shape of the seafloor, saidBryant, who was swept along in a 1.5 knot current. He believes somereach more than 2.5 knots.

“Those are exceptional, high currents,” he said. “We seelarge geological features, furrows, that are the result of thesecurrents.”