Applying the criteria in Article 76 of the Law of the Sea Convention requires data on the morphology of the seafloor and, in some areas, the thickness of the underlying sediment. For this reason, the ECS Project has conducted field programs necessary to collect bathymetric and seismic data.
Bathymetric data are collected using state-of-the-art multibeam echosounders that provide a three-dimensional map of the surface of the seafloor. These data are important for applying the criteria in Article 76, including identifying the foot of slope and 2,500 meter (m) isobaths (i.e., depth contours).
Bathymetric data collection for the ECS Project is coordinated through the Center for Coastal and Ocean Mapping/Joint Hydrographic Center (CCOM/JHC), a cooperative partnership between NOAA and the University of New Hampshire. Since 2002, CCOM/JHC has mapped more than two and a half million square kilometers of the ocean floor, an area the size of Alaska and Texas combined. These data were collected on thirty-one cruises in ten regions totaling nearly two-and-a-half years of sea time (Table 1.1).
|ECS Region||Dates||Ship||Bathymetric Data
|Arctic||Aug 30-Sep 10, 2003||USCGC Healy||10,000|
|Oct 6-26, 2004||USCGC Healy||20,000|
|Aug 16-Sep 14, 2007||USCGC Healy||70,000|
|Aug 14-Sep 5, 2008||USCGC Healy||34,600|
|Sep 5-Oct 1, 2008||USCGC Healy||29,158|
|Aug 7-Sep 16, 2009||USCGC Healy||66,135|
|Aug 3-Sep 4, 2010||USCGC Healy||47,663|
|Aug 15-Sep 28, 2011||USCGC Healy||58,000|
|Aug 26-Sept 27, 2012||USCGC Healy||68,600|
|Sep 19-Oct 6, 2016||USCGC Healy||14,000|
|Atlantic||Aug 23-Sep 18, 2004||USNS Henson||255,000 (total all three legs)|
|Sep 25-Oct 20, 2004||USNS Henson|
|Oct 29-Nov 29, 2004||USNS Henson|
|Apr 29-May 30, 2005||USS Pathfinder||148,500 (total both legs)|
|Jun 5-23, 2005||USS Pathfinder|
|May 1-31, 2008||Roger Revelle||124,216|
|July 3-17, 2012||Ronald H. Brown||69, 287|
|July 30-Aug 29, 2015||Marcus G. Langseth||157,166|
|Bering Sea||July 7-28, 2003||Davidson||21,000|
|Gulf of Alaska||Jun 24-Jul 29, 2005||Kilo Moana||321,466|
|Gulf of Mexico||Jun 21-Jul 8, 2007||Northern Resolution||32,300|
|Johnston Atoll||Aug 9-22, 2014||Kilo Moana||97,250|
|Kingman Reef & Palmyra Atoll||May 12-Jun 16, 2010||Kilo Moana||107,435|
|Nov 20-Dec 20, 2015||Kilo Moana||164, 200|
|Jan 12-Feb 9, 2016||Ron Brown||166,756|
|Mendocino Ridge||May 5-26, 2009||Okeanos Explorer||14,136|
|Sep 23-Oct 11, 2014||Atlantis||103,074|
|Necker Island||Aug 21-Sep 3, 2009||Okeanos Explorer||18,207 (total both legs)|
|Sep 12-26, 2009||Okeanos Explorer|
|Jul 31-Aug 10, 2011||Kilo Moana||47,394|
|Nov 15-Dec 21, 2017||Kilo Moana||149,770|
|Northern Mariana Islands and Guam||Oct 15-Nov 15, 2006||USNS Bowditch||92,111|
|Nov 16-Dec 17, 2007||USNS Bowditch||92,151|
|Aug 6-Sep 5, 2010||USNS Sumner||187,503|
|Sep 24-Oct 21, 2010||USNS Sumner||156,023|
|Sep 14-Oct 13, 2016||Fugro Supporter||102,440|
The second primary dataset is seismic data, which provides information on the depth, thickness, geometry, and other characteristics of the sediments lying on the seafloor. The ECS Project requires seismic data to derive the thickness of the sediment for those regions where the sediment thickness formula in Article 76 applies.
Seismic data is collected by a sound source towed behind the ship which emits acoustic energy at constant time or distance intervals. The transmitted energy is reflected or refracted from boundaries between various geologic layers (such as sedimentary horizons) and received in an array of hydrophones towed behind the ship called a seismic streamer or in a self-contained instrument deployed in the water behind the vessel (sonobuoy) or resting on the seafloor (ocean bottom seismometer). The signals are recorded in digital form and stored on high-speed computers for subsequent processing, analysis, mapping, interpretation, and display.
Seismic data collection for the ECS Project is coordinated through the U.S. Geological Survey. Seismic data collection has been completed in the Arctic, Atlantic, Bering Sea, and Gulf of Alaska (Table 1.2). USGS made significant efforts to minimize the impact of seismic data collection on living resources through careful planning, obtaining the applicable authorizations, and following mitigation strategies.
Seismic data in the Arctic Ocean was conducted in a cooperative effort with Canada. The U.S. Coast Guard Cutter (USCGC) Healy collected multibeam bathymetric data and created a straight and open path through the ice for the Canadian Coast Guard ship Louis S. Saint Laurent, which followed collecting seismic reflection and refraction data with sensors towed behind the stern of the ship.
|ECS Region||Dates||Ship||Seismic Data
|Arctic||Aug 30-Oct 11, 2007||CCGS Louis S. St-Laurent||2,987|
|Aug 21-Oct 3, 2008||CCGS Louis S. St-Laurent||4,217|
|Aug 6-Sep 16, 2009||CCGS Louis S. St-Laurent||4,069|
|Aug 4-Sep 15, 2010||CCGS Louis S. St-Laurent||3,600|
|Aug 18-Sep 29, 2011||CCGS Louis S. St-Laurent||1,437|
|Aug 11-Sept 3, 2016||CCGS Louis S. St-Laurent||629|
|Bering Sea||Aug 10-Sep 2, 2011||Marcus G. Langseth||2,200|
|Gulf of Alaska||Jun 6-26, 2011||Marcus G. Langseth||3,200|
|Atlantic||Aug 21-Sept 13, 2014||Marcus G. Langseth||2,760|
|Apr 10-May 3, 2015||Marcus G. Langseth||3,005|
Training and Data Support
The U.S. ECS Project has assisted more than 30 countries in their efforts to delineate their extended continental shelves. The Project has also benefitted from the experiences and views of other countries and experts.
Over the past 10 years, the National Centers for Environmental Information (NCEI, formerly the National Geophysical Data Center) has provided bathymetric and seismic data directly to at least 20 countries. Data has been provided directly to: Bangladesh, Costa Rica, Cuba, Kiribati, Malaysia, Papua New Guinea, The Bahamas, Trinidad and Tobago, United Kingdom, Vietnam, and South Africa. NCEI also provided data to the United Nations Environment Programme (UNEP) and its efforts to assist other countries including: Cabo Verde, Chile, Ecuador, Madagascar, The Maldives, Mauritania, The Gambia, Guinea, Guinea-Bissau, Senegal, Sierra Leone, Somalia, and Vanuatu. Many other countries have downloaded data from NCEI servers in support of their ECS delineation efforts.
In September 2015, the U.S. ECS Project hosted a week-long training session on how to delineate an ECS and compile the necessary analysis and documentation. The training was conducted in cooperation with the UN Division for Ocean Affairs and the Law of the Sea (DOALOS) and included present and former members of the Commission on the Limits of the Continental Shelf. Nearly 50 ECS specialists from numerous countries of the Americas and Pacific islands participated.
Cooperative Data Collection with Canada in the Arctic Ocean
Much of the data necessary to delineate the continental shelf of the United States and Canada in the Arctic Ocean was collected cooperatively in a two-ship operation.
The U.S. Coast Guard Cutter (USCGC) Healy collected multibeam bathymetric data and created a straight and open path through the ice for the Canadian Coast Guard ship Louis S. Saint Laurent, which followed collecting seismic reflection and refraction data with sensors towed behind the stern of the ship.
This two-ship approach, conducted over four field seasons, collected more than 13,000 linear kilometers of seismic data; this joint work was both productive and necessary in the Arctic’s difficult and varying weather and ice conditions. This collaboration saved millions of dollars for both countries, provided data both countries need, ensured that data are collected only once in the same area, and increased scientific and diplomatic cooperation.