PISCES 5 Dive 610
Vailulu’u Seamount NW and W breaches and Nafanua Volcano

The goal of this dive was to explore the western summit, the SW basin and Nafanua shield volcano. We were to deploy a current meter, exposure experiments, temperature loggers and MAPRs on the western-most summit. Also we took samples on sites including Lefaleleilagi, the SW upper terrace, on the recently discovered Nafanua shield volcano in the western portion of the crater, and below and at the NW breach.

Eel City	Temperature Recorder and Exposure Experiment at Marker 5
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We located the W summit, deployed Marker #2 and the current meter with the Titan arm and deployed an exposure experiment. We took a sediment scoop (#8), rock X1 and deployed exposure experiment #107. We then descended into the SW basin and effectively could not find any vents because of intense “smog” that allowed us to see barely past the basket. It is likely that there are hydrothermal vents in this region, but it was not possible to find them with the amount of time available. So we proceeded to a little summit at the northern edge and took rosette samples R1 and R2.

After this, we went on to the summit region of Nafanua and established Marker #3. We deployed MAPR #16 and exposure experiment #103. During repositioning of the marker the hill collapsed and buried the marker. We established a second site right next to it within a small hydrothermal vent, took rosette samples 3, 4, 5, a rock X2, deployed temperature probe #32. (3332), triggered the Niskin bottle, took sediment scoop #10. The area is covered with microbial mats up to several cm thick and there are cavernous spires (a few meters high and 5 m wide at base) with dozens of eels occupying the cavities.

We established Marker #5 at 920 m below the NW breach, and deployed charge #104 and temperature recorder #3004. Finally, we relocated Marker #1, took Scoop #11 and deployed exposure experiment #105.

Dive Information

Location: W summit (Lefaleleilagi) Vailulu’u Seamount, upper crater bench, Nafanua Volcano, NW breach
Mission Date: Thursday, March 31, 2005
Maximum Depth: 919 m
Project Title: Bio-Hydro and Lithosphere interactions at Vailulu’u Seamount
Principal Investigators: Dr. Hubert Staudigel and Dr. Craig Young
Observer 1: Hubert Staudigel
Observer 2: Co-pilot C. Wolterman