Delineating the U.S. Extended Continental Shelf Active

Within DOI, the USGS Coastal and Marine Hazards and Resources Program (CMHRP) leads the ECS effort to collect, analyze and synthesize geological and geophysical information. The CMHRP’s key role in the ECS effort is acquisition and interpretation of both legacy and new seismic data to measure sediment thickness on U.S. continental margins and understand the geologic processes controlling seafloor morphology. The CMHRP also describes the geological framework of U.S. continental margins in support of the U.S. effort to delineate its ECS according to the Law of the Sea Convention. CMHRP scientists have collaborated with international geological surveys and numerous academic partners to complete ECS studies.

While the CMHRP’s formal responsibilities are to supply data for identifying the outer limits of the U.S. ECS, the newly acquired data have led to significant geological discoveries. In the Arctic Ocean north of Alaska, the seismic data have revealed the tectonic processes that led to opening of the basin. Rocks collected from the seafloor more than 600 km north of the Alaskan Arctic coast have provided new information about high concentrations of critical and strategic seafloor minerals. In the Bering Sea, the seismic data acquired for U.S. ECS purposes have been applied to better understand the distribution of gas hydrates in the basin. In the Atlantic Ocean, ECS seismic data provide the first complete subseafloor view of the 375 km long Cape Fear submarine landslide, the largest submarine landslide documented offshore of the U.S. east coast. The CMHRP also contributes geological expertise to the ECS Task Force on other U.S. margins, including those of the Gulf of Mexico, Pacific west coast, Gulf of Alaska, Hawaiian Islands, and U.S. territories.