ATLANTIC CITY, N.J. � The federal government is planning to use sound blasting to conduct research on the ocean floor along most of the East Coast, using technology similar to that which spawned a court battle between environmentalists and researchers in New Jersey this summer.

The U.S. Geological Survey plans this summer and next to map the outer limits of the continental shelf, and also study underwater landslides that would help predict where and when tsunamis might occur. But environmentalists say it could cause the same type of marine life damage they fought unsuccessfully to prevent this month off the coast of New Jersey.

''New Jersey's marine life, fisheries and coastal economy can't get a break,'' said Cindy Zipf, executive director of Clean Ocean Action, which led a thus-far unsuccessful battle to block a sound blasting research plan off the coast of New Jersey's Long Beach Island.

Although it involves the same basic technology, the new plan is much wider-ranging. It would begin near the U.S.-Canadian offshore border, and extend as far south as Florida.

OFFSHORE eCONOMIC ZONE

John Haines, coordinator of the Geological Survey's coastal and marine geology program, said his research will be low-impact. It is designed to more precisely map the far reaches of the continental shelf to better determine where the United States' exclusive rights to undersea resources such as fish and shellfish extend.

It is not being done to map potential oil, gas or mineral deposits, he said.

''As hard as it is to believe, we don't know in the U.S. where on the seabed our right to protect and use resources ends,'' he said. ''We could extend our ability to use and protect resources hundreds of miles offshore.''

The nation's exclusive economic zone extends for 200 miles, but that could be extended, depending on the results of the research.

Another thing it will examine is sediment that shows past underwater landslides. Data from the study could show which areas of the U.S. and Caribbean coasts could be vulnerable to tsunamis.

The Geological Survey study is due to run for about three weeks in August and September, and a similar period next year, Haines said.

Zipf said researchers would blast the ocean floor with sound waves measuring from 236 to 265 decibels every 20 to 24 seconds for at least 17 days each year of the survey.

Environmentalists say the noise could harm or even kill marine life including whales, dolphins and turtles. Haines said his group is sensitive to those concerns and will take steps to minimize harm to marine animals, including stopping work when animals are seen nearby.

He said this year's planned research will stretch from the U.S.-Canadian border to North Carolina; research farther south would be done next summer.

The plan needs the approval of the National Oceanic and Atmospheric Administration.