PISCES 5 Dive 609
Vailulu’u Seamount NW breach and Nafanua Volcano

The goal of this dive was to explore the NW breach of Vailulu’u and the recently discovered Nafanua cone in the western portion of the crater. Several instruments and exposure experiments were to be deployed in the crater, and in the spillway of water from the NW breach to a channel north of Nafanua volcano.

Sea Anemone near NW Crater Breach	Current Meter Deployed in NW Breach
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We found the NW breach, deployed the current meter with the Hyco-arm and explored a newly developed volcano in the Western Crater. We had to abandon sampling and the deployment of exposure experiments because of a failure of the Titan arm. Nafanua volcano was first mapped by using the KOK center beam in several crossings across the western crater. This volcano must have grown in the last four years because CTD crossings in 2001 still were consistent with the old crater morphology. We traversed the volcano and found the summit at about 707 m water-depth. The basal portion of the cone displays relatively large pillows, and higher up pillows look almost like very fluid Pahoehoe that collapsed and/or transitioned into Aa flows. Nafanua is a pillow volcano that grew very fast with abundant breccia material from collapsing and draining pillows in particular in the summit region. The summit has abundant diffuse venting with unusually thick microbial mats up to several cm thick. We found an extreme abundance of eels.

Dive Information

Location: Vailulu’u Seamount NW breach and Nafanua Volcano
Mission Date: Wednesday, March 30, 2005
Maximum Depth: 945 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 Max Cremer