USGS Law of the Sea

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By Woods Hole Coastal and Marine Science Center September 23, 2022

The USGS Law of the Sea project helps to determine the outer limits of the extended continental shelf (ECS) of the United States. The ECS is that portion of the continental shelf beyond 200 nautical miles. It is an important maritime zone that holds many resources and vital habitats for marine life. Its size may exceed one million square kilometers, encompassing areas in the Arctic, Atlantic, Bering Sea, Gulf of Mexico, western Pacific, and Pacific west coast. USGS provides geologic measurements and research to help define the ECS collaboratively with the Department of State, NOAA, and other federal agencies.

R/V Marcus G. Langseth entering NY Harbor — R/V *Marcus G. Langseth*

The Law of the Sea project integrates science and law. Article 76 of the Law of the Sea Convention sets forth rules for determining the outer limits of the continental shelf beyond 200 nautical miles (M). Defining the outer limits of the ECS is necessary for determining the exact extent of the area within which the United States exercises its sovereign rights and jurisdiction. The size of the U.S. ECS is roughly 1 million square kilometers, more than twice the area of the state of California. The resources in the U.S. ECS are worth many billions if not trillions of dollars.

Why study the ECS?

Photograph of Ice conditions in the Arctic from CCGS Louis S. St-Laurent. — Ice conditions in the Arctic from CCGS Louis S. St-Laurent, a Canadian Coast Guard Heavy Arctic Icebreaker.

The United States, like other countries, has an inherent interest in knowing, and declaring to others, the exact extent of its ECS and thus the sovereign rights it is entitled to exercise in this part of the ocean. Defining those limits in concrete geographical terms provides the specificity and certainty necessary to protect, manage, and use the resources of the ECS. The collection and analysis of the data necessary to establish the outer limits of the U.S. ECS also provides a better scientific understanding of our continental margins. Department of State ECS FAQ

The USGS conducts research to provide geologic framework, seafloor processes, and sediment thickness measurements to identify and establish the outer limits of the U.S. ECS. With its national knowledge and expertise of the U.S. continental margins, USGS has responsibility for developing a database of sediment thickness and continental margin geology, assessing existing data, and developing scientific research opportunities. USGS conducts complex, lengthy field experiments in the regions beyond 200 M. USGS also advises the Department of State about the possible geologic criteria used by other coastal States to identify their ECS limits. Finally, this project includes a task to investigate the mineral resource potential of the U.S. EEZ and ECS. USGS studies help enable the federal government to make informed decisions relating to boundary negotiations, resource development, and resource conservation in the deep-water areas of the U.S. continental margins, including those beyond 200 M.

Seismic Field Programs for USGS ECS Research — Seismic Field Programs for USGS Extended Continental Shelf Research

For this project, USGS works within the framework of a federal interagency U.S. ECS Task Force, chaired by the Department of State and co-vice-chaired by NOAA and Department of the Interior. The Task Force approves project goals and work plans that are developed by the three cooperating agencies.

USGS has led or participated in ten field programs in four regions to collect seismic reflection data to support delineation of the U.S. ECS. Because of the absence of seismic data in the area north of Alaska, the Arctic Ocean represents the largest seismic effort of the project (~17,000 km of seismic track data, collected collaboratively with the Geological Survey of Canada during six field programs in remote ice-covered areas). The Atlantic required the second largest effort (two field programs, ~5400 km of seismic track data). The Bering Sea and Gulf of Alaska each required one field effort, collecting ~3000 km of data in each region.

The USGS Law of the Sea project is a programmatic effort by the Coastal and Marine Hazards and Resources Program (CMHRP), involving participants from the Woods Hole Coastal and Marine Science Center (WHCMSC), the Pacific Coastal and Marine Science Center (PCMSC), the Geology, Minerals, Energy and Geophysics Science Center, and as well as the CMHRP Program Office. From 2002 through 2022, WHCMSC is home base for the active project. From 2023, Law of the Sea activity continues as a task within the USGS Global Marine Minerals project, based within PCMSC.

Photograph of Seismic Lab aboard R/V Marcus G. Langseth — Seismic Lab aboard R/V *Marcus G. Langseth*

Photograph of a Snowy Owl in flight — Snowy owl visitor to CCGS *Louis S. St-Laurent* in the Arctic Ocean

Below are other scientific efforts related to this project

Below are data products associated with this project.

Woods Hole Coastal and Marine Science Center Sediment Laboratory

The Woods Hole Coastal and Marine Science Center Sediment Analysis Laboratory is a resource that performs analyses relating to grain size, mineralogy, composition, and sedimentary character of samples collected by WHCMSC researchers and their partners using state of the art techniques and analytical equipment.

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