Science Report:
After weeks of preparation we are on our way to Axial Volcano on the Juan de Fuca Ridge! Leg 2 of the 2000 Vents Program, featuring bottom pictures and sampling using the remotely operated vehicle ROPOS, finished in Victoria BC on July 18. Leg 3 departed Victoria on July 20 and is returning again to Axial Volcano, as well as other hydrothermally active locations on the Juan de Fuca Ridge. This Leg will concentrate on studying hydrothermal plumes in the water column. Hydrothermal plumes are created when hot vent fluid mixes with cold seawater to form clouds of diluted hydrothermal emissions. These plumes are carried away with the deep-sea currents like campfire smoke in a gentle breeze, becoming more dilute the farther they travel and mix with the surrounding seawater.

Mapping and sampling the plumes can tell us a lot about what is happening on the seafloor. We can estimate the chemical composition of the hydrothermal vent fluids by what we find in the plumes, and we can estimate the amount of fluid coming out from an entire vent field by the size and concentration of the plume that overlies it. We have studied plumes at Axial since the volcanic eruption of January 1998 and have learned that the hydrothermal system created by the eruption was extremely widespread and vigorous immediately after the eruption. Since then the field has slowly declined so that by the summer of 1999 the volume of fluids being discharged was only about 10% of that just after the eruption. One of our objectives on this leg is to find out if this rate of decline has continued in the past year.

But before we can do science we have to get our gear ready. Tomorrow we will be testing some of our equipment and preparing to recover instruments that we left on the seafloor a year ago. Tune in tomorrow to see if we get our gear back from the deep blue sea!