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-Sep 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|
|Jul 3-17, 2012||Ronald H. Brown||69, 287|
|Jul 30-Aug 29, 2015||Marcus G. Langseth||157,166|
|Oct 3-24, 2018||Okeanos Explorer||58,000|
|Bering Sea||Jul 7-28, 2003||Davidson||21,000|
|Gulf of Alaska||Jun 24-Jul 29, 2005||Kilo Moana||321,466|
|Jul 1 – Aug 3, 2018||Kilo Moana||98,777|
|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-Sep 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-Sep 13, 2014||Marcus G. Langseth||2,760|
|Apr 10-May 3, 2015||Marcus G. Langseth||3,005|