Volcanic Vents Found on Ocean Floor Off Oregon

Like high-tech prospectors, scientists aboard a Navy submersible have found a large field of volcanic vents spewing 500-degree water into the Pacific Ocean off the coast of southern Oregon.

The find 100 miles offshore represents only the fourth area in the world’s oceans and the second off the U.S. West Coast where such high-temperature vents have been discovered. Scientists say it could also prove the most easily accessible site for studying how such vents--thought to exist worldwide--influence natural phenomena ranging from the ocean food chain to the weather.

“It was extremely exciting. We went down and hit it on the first dive because we worked out a strategy,” said Peter J. Rona, chief scientist on the dives aboard the Navy submersible Sea Cliff. “We put a mark on the map where we thought it was, based on all the groundwork we had done . . . (and) it was right where the mark was.”

Crew Set Sail

Aboard the Sea Cliff’s mother ship, the Laney Chouest, Rona and other scientists landed in Eureka in Northern California on Friday before the ship’s crew set sail for home base in San Diego, where they are to arrive in mid-October.

Rona is an oceanographer in the National Oceanographic and Atmospheric Administration’s program to study the effect of sea floor venting on the oceans. Some scientists speculate that such vents eventually will be shown to play a key role in many processes, including the tropical ocean current known as El Nino as well as the greenhouse effect.

The quarter-mile-square vent field was located Sept. 23 at a depth of 10,000 feet, about 1,000 feet up a canyon wall in a rugged undersea valley where two plates of ocean crust are spreading apart, Rona said. The collection of huge mountains and valleys in which it lies is known as the Gorda Ridge.

As the submersible cruised through the area, scientists saw 10-foot mineral chimneys deposited as the mineral-rich hot water mixed with the cold ocean waters. Nourished by the sulfur in the vent water, tube worms several feet high carpeted the area, with their red plumes waving in the sub’s wake. Sea floor geysers spewed out smoky, mineral-rich water in some places, Rona said, while others showed only a telltale shimmer of warm water rising.

Rona and others have suggested in the past that, once such areas were found on the Gorda Ridge, they would provide the United States with its best opportunity to establish a scientific preserve at the bottom of the sea.

Such vents are thought to exist all along the sea floor for many thousands of miles, wherever plates of crust are spreading apart and exposing hot volcanic rocks. Until last week’s find, however, the only places where large, hot-water vent fields had been located were about 250 miles off the Pacific Northwest coast, near the Galapagos Islands and in the Atlantic Ocean 1,800 miles east of Miami.

4 Summers of Research

This find came after only four summers of research cruises to the Gorda area, compared to the 13 years Rona said it took him to find the Atlantic vents in 1985.

The reason is that on the Gorda Ridge oceanographers for the first time were able to use sensitive sonar, chemical measurement and video techniques to hone in on the location of a vent field, said Christopher Fry, an NOAA geophysicist in the vents program.

“It completely changes the game,” Fry said. “Just like satellites can sense the Earth, we’re doing remote sensing on the ocean floor.”

The technique was also used earlier this summer to locate a half-mile-long system of cracks northwest of the Gorda site that apparently belched a huge amount of hot water into the ocean two years ago. That event, known among NOAA scientists as “megaplume,” has strengthened the notion that geologic processes under the ocean may have a major effect on the ocean’s chemical and temperature cycles and on climate.