Participant Perspective - July 28, 2001

Interview with Dave Butterfield
Chemical oceanographer - PMEL

Jeff G: In monitoring the vent chemistry at Axial, are there any surprises so far this year?

Dave: In the SE eruption zone things are cooling off. Cloud vent (where we put the NeMO Net RAS) has been steadily decreasing in temperature since we first measured it in 1998. Some of the other vents seem to be more stable. ASHES has been chugging along since we've been coming out here in the late 1980's and hasn't really changed very much. The structures there haven't grown very much and the chemistry hasn't changed a lot either. There haven't been any real surprises. However, we haven't gone back and done the detailed work in the lab yet to see what we've got. Overall, we've seen the disappearance of widespread venting that occurred right after the eruption and it seems to be focusing down to a few areas. It turns out that those areas are the same ones that have historically been diffuse vent areas before the eruption. There's something about those locations that focuses the flow.

Jeff: What's the RAS (Remote Access Sampler) going to do for our understanding of the chemistry of vents?

Dave: It's going to monitor what happens over a year. During the first part of this experiment we put the RAS in for 28 hours to see if there's any tidal periodicity in the temperature or chemistry of the vent fluids. It looks like there isn't much. That's what we suspected because every time we come out we measure very close to the same temperature over the course of a few days. The RAS is there to follow long-term trends of the temperature and the chemistry of the fluids at Cloud vent. If there's some type of tectonic or volcanic event out here, we have a sampler sitting in vent flow. So, if you see a change that's coming from the hydrothermal system, we'll catch it. If there's an eruption, we'll sample quickly to see what we can find in the first few hours or days after the eruption. We'll be keeping careful track of the SOSUS array of hydrophones used to detect submarine earthquake activity.

Jeff: Is the RAS a step toward an autonomous underwater vehicle (AUV) out here?

Dave: The RAS is not the ideal response to a volcanic event because we don't know where it's going to happen. The South Rift Zone is the most active area so it's the likeliest spot for an eruptive event. Project Neptune is a proposed program to put a fiber optic cable all along the Juan de Fuca Ridge. It would provide a lot of power and data transmission capabilities so you could potentially operate a ROV or AUV. It's very expensive and we're not exactly sure how it's going to happen. There's a small proto-Neptune project going on next year that will go for five years. It was designed to install some network experiments on the seafloor that will be similar to what we could do with Neptune. It won't have the cable so it's going to use the acoustic satellite buoys, much like the RAS system. It's a small step. An AUV or ROV operated from shore needs to be done. Personally, I think somebody had better just give it a try. We've been talking about it for 10 years and it's time to put something in the water and see if it works.