Missions and Data

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

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
(sq km)

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

 

Seismic Data

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
(linear km)

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