New Map Of Oceans Floors Researchers Declassified Satellite Data Made Project Possible

Scientists using data from space satellites have produced a spectacular map of the entire ocean floor, showing undersea volcanoes, ridges and trenches in far greater detail than available ever before.

“It’s like being able to drain the oceans and look at the Earth from space,” David Sandwell, a researcher at the Scripps Institution of Oceanography in La Jolla, Calif., said Monday.

The map will be valuable to commercial fishermen, oil companies and global climate researchers, said Walter Smith, a geophysicist at the National Oceanic and Atmospheric Administration.

Previous ocean maps created by ship soundings left uncharted areas as big as Kansas, Smith said. The new map reveals features as small as 6 miles across, about the size of the District of Columbia.

Sandwell and Smith displayed their new, full-color maps of the ocean bottom at a news conference in Washington on Monday.

The data became available to researchers in July, when the Navy agreed to declassify formerly secret measurements made from space to aid in submarine navigation, such as that portrayed in Tom Clancy’s novel “The Hunt for Red October.”

The satellite data “will further the study of the ocean basins in the same way that the Hubble telescope has promoted the study of the cosmos,” said Marcia McNutt, a professor of earth science at the Massachusetts Institute of Technology.

Among its many features, the new map shows:

Details of a previously discovered 30,000-mile long volcanic range that spans the Pacific Ocean floor like the seam of a baseball.

A unique “triple junction” where the continental plates lying under Africa, India and Antarctica grind and clash beneath the Indian Ocean. The area is “extremely rugged,” Smith said.

A previously unknown bank of shallows in the South Pacific where fishermen from New Zealand are making rich hauls of fish and lobster.

The scars, known as “fracture zones,” on the Atlantic seabed caused by the slow drifting apart of the continents over the past 100 million years.

“In the Atlantic, you can follow one fracture zone from Africa all the way over to North America,” Sandwell said.

The bulk of the information was produced by the Navy’s GEOSAT spacecraft between March 31, 1985, and Oct. 30, 1986, but was classified as secret until last summer. Additional measurements were collected by a European Space Agency satellite over the past year, and the map was produced by NOAA and the Scripps Institution.

The spaceships, orbiting 500 miles from the Earth, used microwaves to measure the distance to the surface of the ocean with an accuracy of 1 inch, Smith said.

After correcting for waves, tides and currents, the measurements showed “bumps” in the ocean surface corresponding to mountains and valleys below. A 6,500-foot undersea volcano, for example, would produce a 6-foot swelling at the surface.

The researchers checked the measurements from space against known shipboard soundings to verify their accuracy.

“This gives us the first overall view of 70 percent of the Earth in very fine detail,” Sandwell said. “We’re having a data feast.”

The data are being made available to researchers, oil companies and other interested persons on the Internet.

Smith said global climate re searchers will find the map useful because undersea ridges and mountains get in the way of ocean currents, forming huge eddies and rings of turbulence. These in turn affect the atmosphere and need to be built into computer models of global warming.

MEMO: This sidebar appeared with the story: HOW TO GET A MAP A large color poster of the new map is available for $40 from the Scripps Geological Data Center in La Jolla, Calif., by calling 619-534-2752. Researchers can obtain the sea floor map and data at the Internet address: http:/ /www.ngdc.noaa.gov/mgg/ announcements/announce- predict.html. The data is also available on four compact discs.