Logbook: August 30, 2006

Position: 45°57.0’N, 130°0.0’W
Axial Volcano

The rope on the seafloor was attached to the NeMO Net buoy, which was not here when we returned to recover it this year. The barnacles on the seafloor were attached to the mooring rope at the surface and ended up on the seafloor when the buoy detached. (click image for larger view)

After recovering the AUV early yesterday morning, we have returned to ROPOS operations. At present we are two-thirds of the way through a long dive to record seafloor pressure and measure the deformation of Axial Volcano. The next dive will focus on detailed chemical and microbiological sampling of the hydrothermal vents on the 1998 lava flow.

At the start of dive 1010 we investigated the seafloor anchor of the lost NeMO buoy. We found that the line had broken off near the surface buoy and fallen slightly to the NW of the anchor. A heavy accumulation of long-neck barnacles on the upper portion of the line fell to the seafloor, where crabs were feasting on them.

Our monitoring of Axial Volcano has three basic components: 1) Acoustic monitoring of seismic and volcanic activity, 2) physical or geodetic measurements of the shape of the volcano and 3) monitoring the output of hydrothermal activity. In the long term, we are trying to see how these three things tie together.

We already deployed 4 Ocean Bottom Hydrophones (OBHs) that will monitor activity around the caldera for the next year. This will allow us to hear smaller events than we can already detect with the remote SOSUS hydrophone network.

In addition, we are also testing a new instrument that can drift as it descends and ascends through the water. Haru Matsumoto’s Que-Phone was deployed in the open ocean for the first time early Tuesday morning. Its mission was to record sound while sinking to the bottom of the caldera and then return to the surface and make a satellite phone call to report its position and information about data collected. It surprised us a little by showing up early, but the reported position and drift was perfect, as it brought the Que-Phone within a mile of the ship. It was spotted from the bridge and a small boat picked it up and brought it safely on board without interrupting ROPOS operations.