Research Sub Finds Volcanic Hot Spot on Pacific Floor : Area of Vents Off the Coast of Oregon May Provide Clues to Mysteries Under Water and Above

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

The discovery 100 miles offshore represents only the fourth area in the world’s oceans and the second off the West Coast where such high-temperature vents have been found. Scientists say it also could prove to be 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 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.”

Based in San Diego

Rona and other scientists landed in Eureka in Northern California on Friday aboard the Sea Cliff’s mother ship, the Laney Chouest. The ship’s crew then set sail for its home base in San Diego, where it is due to arrive in mid-October.

Rona is an oceanographer in the National Oceanographic and Atmospheric Administration’s program to study the oceanic effect of sea-floor venting. 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 and the greenhouse effect.

The quarter-mile-square vent field, which lies under about 10,000 feet of water, was found Sept. 23, about 1,000 feet up a canyon wall in a rugged 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-high chimneys that had been deposited as the mineral-rich hot water hit the cold ocean. Nourished by the sulfur in the vent water, tube worms several feet high carpeted the area, their red plumes waving in the sub’s wake. Sea-floor geysers spewed out smoky-colored, mineral-rich water in some places, Rona said, and others showed just a shimmer of warm water rising.

Rona and others had suggested 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.

Crust Spreading Apart

Such vents are thought to exist all along the sea floor for many thousands of miles, wherever plates of the Earth’s 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.

This find came after only four summers of research cruises to the Gorda area, contrasted with the 13 years Rona said it took before he found 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 the 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 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 big effect on the ocean’s chemical and temperature cycles and on climate.

The one-month cruise to the Gorda Ridge was sponsored by a joint state-federal group known as the Gorda Ridge Task Force, made up of federal officials and public and private representatives of California and Oregon.

Although officials have determined that mining of the minerals at the site would not be economical, research is expected to continue. Oceanographers involved have come from several institutions, including UC San Diego and the Scripps Institution of Oceanography. The Navy provided the sub and support ship free as part of its program to support scientific research.