The Office of NOAA Corps Operations authorized the NOAA Ship MCARTHUR to respond to the event (GREAT I). It departed March 7 from the NOAA Pacific Marine Center in Seattle and returned on March 15 to Seattle. A report from a team of investigators from NOAA (E. Baker, Chief Scientist), Oregon State University, the University of Hawaii, and the University of Washington on the NOAA Ship MCARTHUR details the discovery of a large hydrothermal plume ("Megaplume") near 42 39'N, 126 47'W. The latest information on the response effort is on the World Wide Web at "http://www.pmel.noaa.gov/vents/eruption.html". The web site is being updated on a daily basis.
As the result of this success in quick response, the National Science Foundation has authorized the WECOMA to return to the site in early April to conduct further studies of this event in collaboration with NOAA.
(1) Locating the source of the Megaplume(s) on the seafloor; establishing the spatial pattern of seafloor breakage, eruption, etc. This information is critical to better understanding of the origin of megaplumes, i.e., whether they arise from rapid quenching of dike injection/ seafloor eruption, from breaching of preexisting fluid reservoir, or both.
(2) Establishing whether there's been a subsurface bacterial bloom. Injection of magma into the upper ocean crust is hypothesized to cause blooms of the subsurface biosphere, including thermophilic and hyperthermophilic species. Since thermal decay of dikes is descibed by a power law, the population of these species resulting from this process also rapidly dimishes, making sampling of culturable species more difficult/unlikely as time goes on. Hence there is a critical need to localize the sources as soon as possible. Culturable hyperthermophiles disappeared sometime between four months and one year from the initial diking event detected by SOSUS.
(3) Advancing the time series measurements of megaplume geochemical and microbial parameters to establish patterns and rates of change in water chemistry and microbial community structure. McARTHUR cruise provided the initial time point; obtaining a second time point is essential for minimum time series observations. The earliest stages of the plumeÕs geochemical and microbial development will be most dynamic. In addition to additional sampling of a megaplume, at least one neutrally buoyant RAFOS float will be emplaced in the plume to trace its movement in coming months in the hope of relocation and resampling in the summer of 1996.
(4) If a lava eruption site is found, attempt to obtain samples of it by dredging or rock coring.
(1) CTD/rosette/SUAVE capability--
The NOAA/PMEL Sea Bird CTDT/rosette system will be used. The advantage is that it comes with software designed to process and display plume data. The CTD/rosette system will collect samples and data for a number of NOAA and NSF investigators, including: (1) Fe, Mn and other trace metals, (2) particulates for mineralogical and biogeochemical studies, (3) gas, including He, CH4, CO2 and others, (4) temperature, conductivity and transmission loss in the water column. PMEL (G. Massoth) will bring an in situ chemical analyzer (SUAVE) capable of taking almost continuous measurements of Fe and Mn in the plumes and can be strapped on concurrently with the CTD. The primary winch used will be the hydrographic winch with the 10000 m of .322" 3 conductor cable. The CTD package will be used in two modes. In the first mode, the package will be towed at slow speeds (~2 knots) for long periods of time and will be yo-yo'd through the bottom ~1000 m of water (the "Tow-Yo"). The second mode will be the standard vertical cast.
(2) Camera/sidescan system--
Successful localization of the seafloor vents will require a deep-towed camera system. A self-recording CTD can also be mounted on the frame. The system being used on this cruise is the WHOI system developed by Dan Fornari and Earl Young for use on the AII nighttime operations with a standard trawl cable (in this case, the .5" cable on the coring winch towed through the stern A-frame. It consists of a 35 mm still camera and a new Benthos digital still camera. Snapshots would be taken at a 15-30 second repetition rate. A telemetering pinger will allow monitoring of temperature anomaly and strobe flash on the ship's LSR. The digital camera data will be viewed on board and selected portions of the 35 mm film will be processed as necessary. We have requested to have a slave winch control set up by the LSR in the dry lab.
(3) If a megaplume is located, deploy RAFOS floats--PMEL has two floats that are being prepared (ballasted) by the Naval Postgraduate School in Monterey.
(4) Navigation-- We will be depending on the ship to provide the standard GPS navigation. In addition, we are planning to track the camera sled using by one of two methods: (1) Ranging on a relay transponder attached to the sled, or (2) using a long-baseline navigation system. This will require deployment of at least 3 bottom moored transponders. The transponders will be interrogated using alternate cycles of ship- transponders-ship and ship-sled-transponder-ship to obtain precise positions of the camera sled (and perhaps CTD). In order to interrogate the transponders we will require towing a small fish (supplied by science party). Part of this system is a PC set up on the Bridge so that the bridge watch will be able to monitor the position of camera sled and its relation to targets, transponders, as well as the ship's position.
(5) Rock Dredging/rock coring-- A dredge has been put on board in San Diego (loaned from the ATLANTIS II). A small gravity corer with a special cutting edge for sampling basaltic glass will be put on board before sailing. These will only be used in the event of location new lava flows with the camera sled.
1 April-- OSU Marine Techs only - lab setup
2 April -- Fueling-- possibility of some hand-carry loading and light setup
by PMEL (no guarantees), lab setup by OSU Marine Techs.
3-5 April-- Scientific loading/setup, stores loading will take place
sometime in this period
NAME AFFILIATION ROLE ON CRUISEDr. Jim Cowen U. Hawaii Chief Scientist M Dr. Bob Embley NOAA/PMEL Co-Chief Scientist M Dr. Ed Baker NOAA/PMEL Plume Oceanog. M Mr. Gary Massoth NOAA/PMEL Chemist M Dr. Bill Chadwick CIMRS/OSU Geologist M Dr. Debbie Kelley U. Wash. Chemistry/Geology F Mr. Ron Greene CIMRS/OSU Gas Chemistry M Mr. Kevin Roe JISAO/NOAA Chemistry M Mr. Eric Olsson U. Washington Gas Chemistry M Ms. Melanie Summit U.Washington Microbiology F Ms. Cara Wilson Oregon State U. Chemistry F Mr. Geoff Lebon JISAO/U. Wash. Chemistry M Ms. Susan Hanneman Contractor Camera F Mr. Xiyuen Wen U. Hawaii Microbiology/Chem. M Mr. Earl Young WHOI Camera Engineer M Mr. Tim Shank Rutgers U. Biology M