Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, February 14, 1993 TAG: 9302140100
SECTION: NATIONAL/INTERNATIONAL PAGE: A-8 EDITION: METRO
SOURCE: NATHANIEL C. NASH THE NEW YORK TIMES
DATELINE: BUENOS AIRES, ARGENTINA LENGTH: Long
VOLCANOES SURPRISE SCIENTISTS
Scientists mapping the floor of the South Pacific have found what they say is the greatest concentration of active volcanoes on Earth.Using sonar scanning devices to peer into the ocean depths 600 miles northwest of Easter Island, the scientists aboard the research vessel Melville were surprised to discover 1,133 seamounts and volcanic cones in an area about the size of New York state.
Many of the volcanoes rise more than a mile above the ocean floor. Some are almost 7,000 feet tall, with their peaks 2,500 to 5,000 feet below the sea's surface.
Two or three of the volcanoes could be erupting at any given moment, said Ken Macdonald, a professor of marine geophysics at the University of California at Santa Barbara who was a leading scientist on the project.
Macdonald, along with Tanya Atwater, professor of geological sciences at the University of California at Santa Barbara, and Don Forsyph, a professor of geophysics at Brown University, were surprised by the sheer number of volcanoes they found while conducting surveys aboard the Melville from November to mid-January.
"We thought we would find a few dozen new volcanoes," Macdonald said. "Instead we found over 1,000 that had never been mapped before."
A marine geologist who was not part of the research team, Janet Morton of the United States Geological Survey in Menlo Park, Calif., said, "Though you would expect to find a lot of volcanoes there, 1,100 is a much greater density of activity than other parts of the sea floor." There is no greater concentration of volcanoes on land either, specialists said.
Indeed, the finding underscores just how little is known about the ocean depths. Many scientists say that more is known about the mountains and valleys on the dark side of the moon than about the ocean floor, the last unexplored frontier on Earth. Macdonald estimated that no more than 5 percent of the sea bottom has been mapped in detail.
One potential benefit of the discovery, scientists said, is that the volcanic eruptions are generating large new mineral deposits, including copper, iron, sulfur and gold. Although the minerals cannot be commercially exploited now, they said, future technological advances could make that possible.
The discovery is also likely to intensify speculation over whether volcanic activity, pouring huge amounts of heat into the ocean, could change water temperatures enough to affect weather patterns in the Pacific, an idea that is greeted with skepticism by many scientists.
Scientists are particularly interested in determining whether periods of extreme volcanic activity underwater - when perhaps a dozen or more volcanoes erupt simultaneously - could trigger El Nino, a phenomenon that alters weather patterns around much of the globe every four to seven years.
El Nino occurs when a giant high pressure system centered near Easter Island drops slightly in pressure and triggers a change in the circulation of Pacific currents, bringing warmer water to certain areas and colder water to others. The shift has decimated the South American fishing industry some years and has been held responsible for bringing unusually heavy rainfall to the Southern United States - early last year, for example.
"Volcanic action on the ocean floor is part of the whole of understanding El Nino," said Herbert R. Shaw of the U.S. Geological Survey. "More power to guys like Ken Macdonald."
Macdonald said that most of the volcanoes he mapped had probably erupted in the last few thousand years, making them active in geological terms, and that more than a hundred may have erupted in the last few hundred years.
In several places, he said, the volcanoes were so close that they formed underwater mountain ranges extending up to 300 miles. He said that initial seismic readings from the area indicated that one volcano may be erupting now.
Although much of the sea floor has yet to be mapped, scientists have known that there is much more volcanic activity on the ocean floor than on land.
The latest finding is almost certain to fuel discussion of whether volcanic activity can warm the water enough to affect weather conditions such as El Nino.
In the past few years, scientists from the U.S. Geological Survey and the University of Hawaii have published papers contending that a connection could exist and that it should be thoroughly researched.
Some scientists have noted that the location of the high pressure system that plays a role in El Nino coincides with the location and frequency of intense underwater volcanic activity near Easter Island. Some speculate that if the water temperature in the area warmed slightly, that could be transmitted into the atmosphere, triggering the change.
But many in the scientific community have rejected the theory, arguing that even though eruptions might pour vast amounts of heat into the ocean's depths, a warm-water layer 650 to 1,650 feet from the surface would prevent this warmer water from reaching the surface.
"The ocean is so big, and even if you are putting a lot of heat in a few spots, it just does not have much effect," said Dr. William Chadwick, a volcanologist at the National Oceanic and Atmospheric Administration in Newport, Ore.
Macdonald said, "I have always been one who thought the idea was hogwash, and I remain extremely skeptical." But having surveyed so many volcanoes, he now thinks the idea is worth exploring.
"It is definitely warming the water," he said. "The question is: Could there be periods when maybe a hundred of these volcanoes are simultaneously active, creating so much heat that it climbs up the water columns and gets transmitted into the atmosphere? It's still considered most unlikely."