NeMO July 15, 2001

Logbook: July 15, 2001

Ship arrives at Cleft segment. Dive 618 touched bottom and vehicle returned for cable oil calibration.
Perspective Today: Bill Chadwick, Volcanologist

Science News | Teacher At Sea | Participant Perspective

Cruise Calendar

July-August 2001

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image of ROPOS being lowered to sea, click for full-size

ROPOS, the remotely operated vehicle, being deployed over the side for its first dive on this expedition.

Science News

Science Report - Sunday, July 15, 2001
Ship's position: 44 39.9'/-130 21.7

The first 3 days of NeMO 2001 will be spent at the southern end of the Cleft segment on the Juan de Fuca Ridge where a number of experiments that are designed to measure seafloor spreading are located. Last year we deployed 1 extensometer instruments here and our first task is to download the data they collected over the last year. We arrived at south Cleft early this morning and ROPOS made a brief trip to the bottom (dive R618) but had to return to the surface to top up oil levels (not unexpected since this was its first deep dive with a new tether). A cable to the infrared data port (for downloading the extensometer data) also needed to be replaced. ROPOS will be headed back down to the bottom shortly. After we complete the work at Cleft, we will head to Axial Volcano where we will continue to study the impacts of the 1998 volcanic eruption there.

Teacher's Logbook....(not available today)

Participant Perspective

Interview with Volcanologist Bill Chadwick

Jeff: What are you hoping to find out from the extensometers placed at the South Cleft segment of the Juan de Fuca Ridge?

Bill: It's a long-term monitoring experiment to try and measure actual seafloor spreading events. This has never been done before. Seafloor spreading occurs episodically, once every twenty years or so depending on the spreading rate. All of a sudden it will open up several meters. So, even though the average spreading rate here is 6 cm per year, it's not spreading all the time. Extensometers have a fairly long life time so we're hoping to have them down long enough to catch one of these spreading events. Those data will tell us exactly how spreading is accommodated at the ridge crest. We're also monitoring the hydrothermal vents nearby so we can see the relationship between spreading events and changes in venting activity. More...