NeMO-ROPOS Cruise:

NOAA Ship Ron Brown
July 14-August 1, 2001
Seattle, WA-Newport, OR

This year's NeMO-ROPOS cruise will again briefly visit the Cleft segment of the Juan de Fuca Ridge before going on to NeMO at Axial volcano. At Cleft, we will revisit an array of extensometer instruments to download a year's worth of data. The instruments there are measuring the distance across the ridge axis to look for spreading events, and are part of another seafloor observatory effort sponsored by the NSF/RIDGE Program. Once at NeMO, we will use ROPOS to continue the time-series measurements we have been making on the seafloor since the January 1998 volcanic eruption. This includes taking samples of hydrothermal vent fluids, the microbes that live in them, and the animals that live around the vents. In 1998, we were able to witness the creation of new hydrothermal vent sites and the first biological colonizers on the new lava flow. Since then we have been returning each year to document how these sites are continuing to change and evolve. We will also be recovering and redeploying a variety of seafloor instruments (including a new vent fluid sampling system integrated into the NeMO Net near-real time communication link). These instruments allow us to continue making observations at NeMO between our summer expeditions. Finally, we will be continuing high-resolution geologic mapping of the 1998 eruption site, and geophysical measurements to tell us if Axial volcano is inflating with magma and getting ready for its next eruption.

NeMO-CTD Cruise:

R/V Wecoma
July 16-August 2, 2001
Newport, OR-Newport, OR

The NeMO-CTD cruise will work at the NeMO site on Axial Volcano, as well as on the Cleft segment of the Juan de Fuca Ridge and a hydrothermally active basin of the Blanco Fracture Zone. At Axial Volcano we will be making our fifth water-column cruise since the eruption of January, 1998. We continue to construct a time series of observations of hydrothermal activity to understand how vent fields evolve after an eruption. Work there will consist of two principal activities: water sampling and seafloor mooring recoveries and< deployments. The water sampling will consist of vertical profiles and near-seafloor tows of instruments to map and sample emissions from hydrothermal vents that form extensive plumes in the deep water around the volcano's summit. Water samples will be analyzed for gases, trace metals, and suspended particulate matter in order to map the distribution of the plumes. Moorings left at the summit in 2000 will be recovered and the data downloaded at sea. New moorings will be deployed for recovery in 2002. These moorings monitor the fate of the plumes between our yearly cruises. At the Cleft segment we will be doing similar work to maintain a time series that began in 1986, when a volcanic eruption is believed to have occurred there. Our tracking of hydrothermal activity there is longest such time series anywhere on the seafloor. In the Blanco Fracture Zone, we will investigate the distribution of hydrothermal emissions within the East Blanco Depression, near the southerly end of the Juan de Fuca Ridge. Hydrothermal sources there apparently produce unusual fluids with exceptionally high ratios of helium to heat.

.