VOLCANO ERUPTING OFF OREGON COAST

April 07, 2001 12:00 am

A volcano has been erupting on the ocean floor 130 miles off the southern Oregon coast since Tuesday night, but poses no threat to ships or coastal communities like Brookings.

Curry County Emergency Services Coordinator Mike Murphy said Friday the state Office of Emergency Management hadnt even bothered to issue a bulletin about the event.

He said the volcano is so deep that it probably wouldnt be noticed by ships passing directly over it. He doesnt believe there is any threat to the coast from earthquakes or tsunamis.

Molten lava has been oozing from the volcano, which has generated more than 1,000 earthquakes that continued late Thursday. A few of the quakes have been powerful enough to be detected by land-based instruments, with the largest measuring 4.5 magnitude.

Scientists with the National Oceanic and Atmospheric Administrations Vents Program in Newport have been using undersea instruments to track activity at the site, on the volcanic Gorda Ridge.

The ridge is an undersea formation that runs in a north-south direction off Southern Oregon and Northern California.

Like the Juan de Fuca Ridge farther north off the Northern Oregon and Washington coasts, the Gorda Ridge is a spreading center where molten lava oozes onto the seafloor to form new oceanic crust.

The eruption began about 6 p.m. Tuesday on the Jackson segment of the rugged ridge, about 50 miles south of a volcanic eruption that scientists detected on the ridges Northern Gorda segment early in 1996.

Were mobilizing to get a research ship to check it out, said Robert W. Embley, a marine geologist with the Vents Program. He hopes the research vessel New Horizon, which is operated by the Scripps Institution of Oceanography in San Diego, will be able to reach the site by early next week.

Researchers would like the ship to arrive in time to find megaplumes, gigantic bursts of hot, mineral-rich water that are spewed out of underwater eruptions. Christopher Fox, a geophysicist with the Vents Program at the Hatfield Marine Science Center, said the seismic activity detected by the seafloor instruments is caused by the magma being injected into the ridge and cracking the rock.

Fox said the earthquake activity, which reached a peak of nearly 90 per hour Tuesday evening, had slowed to only a few per hour by Thursday afternoon.

The eruption is the fourth to be detected off the Oregon Coast using a modified version of the U.S. Navys once top-secret array of submarine-tracking hydrophones.

The Newport scientists were the first to witness a seafloor eruption as it was happening shortly after the research system was installed in 1993.

By staff and wire reports