In 2016, NOAA's Office of Ocean Exploration and Research (OER) supported several extended continental shelf (ECS) surveys, including efforts within and in close proximity to the Pacific Remote Islands National Marine Monument; along the Mariana Arc, the West Mariana Ridge, and an unsurveyed portion of the Mariana Trench; and in the Arctic. These surveys are described below. Learn more about OER's overall ECS efforts.
From January 5 to February 9, 2016, NOAA-funded University of New Hampshire scientists, aboard NOAA Ship Ronald H. Brown, conducted a mapping expedition in support of the U.S. Extended Continental Shelf (ECS) Project, whose mission is to establish the limits of the nation’s seabed beyond its 200 nautical mile exclusive economic zone.
The survey occurred within and in close proximity to the Pacific Remote Islands National Marine Monument area of the central Pacific Ocean. The specific objective of the cruise was to complete a reconnaissance of the regional platform from which the Line Islands seamounts and islands rise. These data are critical to understanding where there may be U.S. ECS in this Pacific region. The survey also collected data for the Republic of Kiribati, in support of that island nation’s ECS efforts. Excluding transits, a combined total area of 313,675 square kilomters (91,453 square nautical miles) was mapped. It is anticipated that these data will contribute to scientific baselines in what are often described as difficult-to-reach, poorly understood environments.
The responsibility for funding and conducting the mapping was given to the NOAA by the U.S. Congress, and has been implemented since 2003, through a cooperative agreement with the Center for Coastal and Ocean Mapping/NOAA-UNH Joint Hydrographic Center at the University of New Hampshire.
In the western Pacific, from September 13-October 15, 2016, a NOAA and University of New Hampshire-led team aboard M/V Fugro Supporter surveyed along the Mariana Arc, the West Mariana Ridge, and an unsurveyed portion of the Mariana Trench. Altogether, approximately 32,000 square kilometers of seafloor was mapped during this 30-day survey.
In addition to meeting the U.S. ECS Project objectives, this survey’s data collection efforts are expected to clarify the process by which the breakup of the Mariana Arc occurred – testing two competing hypotheses about the nature of the oceanic crust in the northern part of the wishbone-shaped area. Namely, are the back-arc lavas formed by rifting of the Mariana Arc, or are they formed by seafloor spreading?
The mapping that targeted the area between the Mariana Arc and Trench to the north, where subduction is highly oblique, will also demonstrate whether the uncommon serpentinite mud volcanic features, present along the southern and central portions of the Mariana Forearc, are prevalent everywhere in the Mariana System or whether they occur only where plate convergence is greatest.
In the Arctic, from September 18-October 5, 2016, OER and the University of New Hampshire, Center for Coastal and Ocean Mapping sponsored the tenth and very like final U.S. ECS field survey aboard U.S. Coast Guard Cutter Healy.
With the decision to use the Healy for ECS operations this field season, discussions also began with the Canadians regarding potential synergies, since both nations' ships were scheduled to be in the Arctic. Logistical constraints prevented the scheduling the Canadian and U.S. icebreakers for joint operations; however, both Canada and the U.S. agreed to extend their respective cruises by five days to accommodate high-priority objectives for each other.
Survey priorities included the collection of dredge samples on Alpha Ridge and the collection of bathymetric data in the region north of the Alaskan north slope margin and on the Beringian margin, aimed at strengthening our understanding of our countries’ continental shelf outer limits. Approximately 14,000 square kilometers of seafloor were mapped and 27 kilograms (60 pounds) of rock were collected and catalogued. In addition to helping the U.S. determine the real outer edge of the continent beneath the ocean along the U.S. Arctic coastline, these data open up new scientific avenues of exploration and research.
Ancillary onboard science activities included the deployment of ice buoys (under the direction of NOAA/Navy Ice Center (NIC) personnel) and real-time underway isotopic analyses of seawater samples for ocean acidification studies (under the direction of Jonathan Wynn from the University of Southern Florida), A time-lapse video from this survey in the Arctic is available here .