Deploying the CTD off the fantail of the Wecoma.

R/V Wecoma - CTD Cruise
Science News

Science Report - Wednesday, July 18, 2001
Position: 45deg 56.04' N /130 deg 0.66' W
Chief Scientist Ed Baker

After weeks of preparation we are on our way to Axial Volcano on the Juan de Fuca Ridge, 260 miles off the coast of Oregon. Our cruise on the RV Wecoma, operated by Oregon State University, is one of two cruises this year conducted by NOAA's Vents/NeMO Program. Another NOAA Vents' cruise on the R.H. Brown is also working at Axial Volcano, studying the seafloor with an underwater robot vehicle (ROPOS). Our cruise focuses on mapping and sampling the distribution of hydrothermal emissions, or plumes, in the waters over Axial Volcano and other locations on the Juan de Fuca Ridge. These plumes are produced by the interaction of seawater and hot volcanic rock, sending geysers of hot and warm water up into the overlying seawater from cracks in the seafloor. The plumes are then carried away by deep-sea currents like campfire smoke in a gentle breeze.

We have been studying plumes over Axial Volcano since 1984, but with extra intensity since an eruption of lava on the volcano's summit in February of 1998. This eruption created an enormous and highly active set of hydrothermal vents, and every year since we have monitored the declining activity of this vent field. By the summer of 2000, the discharge of hydrothermal fluid was less than 10% of that just after the eruption in 1998. Our major goal this year is to discover if this decline is continuing. During this cruise we will recover several instruments we left in the vent field last year, plus make many new measurements of the existing plumes.

In our next installment we will report on the moorings we plan to recover, containing an entire year's data on the movement and intensity of Axial's hydrothermal plumes.