USGS plans seismic survey in Bering Sea Shoot is part of effort to delineate potentially resource-rich extended continental shelf; survey also planned in Gulf of Alaska Wesley Loy For Petroleum News
The U.S. Geological Survey plans to shoot a seismic survey in August in the Bering Sea to delineate the “extended continental shelf.”
The survey will be conducted from the research vessel Marcus G. Langseth with a towed array of 36 airguns, says an environmental assessment prepared for the project.
The 235-foot vessel is owned by the National Science Foundation and operated through a cooperative agreement by Columbia University’s Lamont-Doherty Earth Observatory.
National project The extended continental shelf is that region beyond the U.S. Exclusive Economic Zone or EEZ, which reaches to 200 nautical miles offshore.
The USGS seismic survey will be conducted under the auspices of the U.S. Extended Continental Shelf Task Force, an interagency body chaired by the Department of State with vice chairs from the Interior Department and the National Oceanic and Atmospheric Administration.
“The United States has an inherent national interest in knowing, and declaring to others with specificity, the extent of our sovereign rights with regard to the U.S. extended continental shelf,” an area likely rich in resources that could be worth billions or even trillions of dollars, the task force’s website says.
“There are six areas in which the U.S. likely has an extended continental shelf (ECS): the Atlantic Margin, Arctic Ocean, Bering Sea, off the west side of Guam/Northern Mariana Islands, and in two areas in the Gulf of Mexico,” the website says. “There are nine areas in which the U.S. may have an extended continental shelf: the Gulf of Alaska, the western end of the Aleutian Islands, the Northern Mariana Islands, Hawaii’s Necker Island, Johnston Atoll, Kingman Reef and Palmyra Atoll, and three areas off the U.S. west coast.”
Preliminary studies indicate the U.S. extended continental shelf likely is an area about twice the size of California, says the task force website at continentalshelf.gov.
Survey details The R/V Marcus G. Langseth will depart from Dutch Harbor around Aug. 7 and return Sept. 1, the environmental assessment says.
The survey will collect seismic reflection and refraction profiles to be used to delineate the extended continental shelf, the assessment says.
The rules for defining the extended shelf are based in international law, specifically Article 76 of the United Nations Convention on the Law of the Sea.
“One of the conditions in Article 76 is a function of sediment thickness,” the assessment says. “The seismic profiles are designed to identify the stratigraphic ‘basement’ and to map the thickness of the overlying sediments.”
The Langseth survey will take place in the central-western Bering Sea, in both the U.S. EEZ and adjacent international waters, in depths greater than 3,000 meters.
The USGS plans to use the Langseth on a similar seismic survey from June 5 to 25 in the Gulf of Alaska.
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