December 7, 2006
Creation of new seafloor documented as never before
Seismometers in the right place at the right time detected the growing swarm of tiny undersea earthquakes that culminated in a volcanic eruption last January off the coast of Mexico.
It’s the first time any research team has had instruments in place to closely record the series of micro-earthquakes — none more than magnitude 1.5 or so — associated with the formation of new seafloor, according co-authors of the paper “A Seafloor Spreading Event Captured by Seismometers,” in the Nov. 24 issue of Science. Seafloor spreading — a process that is responsible for the formation of nearly three-quarters of the Earth’s crust — is not well understood.
Brooke Love, UW doctoral student in oceanography and one of the co-authors of the paper, is at sea now on the third expedition that has rushed to the site of the eruption in order to document changes in the vent fluid chemistry and temperature, how the ecosystem is responding and to conduct detailed geological mapping
“We are finding some interesting evidence of new colonization by animal communities and lots of changes in the fluid flow and just the whole look of things,” Love wrote in e-mail Dec. 1 from on board the research vessel Atlantis over the East Pacific Rise off Mexico. “The eruption has really created a whole new world down there from what we have known before.”
Love’s contribution to the Science paper concerned the methane that was present at 50 to 100 times normal levels in a 10-mile plume in the water after the eruption.
“The possible source of the methane I was measuring is ‘cooked biology'” she said. Burned up by the lava were lush communities of tube worms and other organisms living off hydrogen sulfide, a gas poisonous to most organisms. That is one probable source of the methane found over the field, she says.
During the current expedition, Love writes, ” My advisor Marv Lilley and I have been collecting samples in gas-tight bottles so that we can get a better sense of how the eruption has affected the fluid chemistry and how it varies in time and space in this area. There was a previous visit by the Atlantis in June so we can compare how things look now, after five months have passed.”
Love earlier this year received a $25,000 Link Foundation Fellowship for a year of work developing instrumentation to measure another important gas in the oceans, carbon dioxide. She’s been exploring an instrument that uses light to make an optical measurement of how much carbon dioxide is present in hydrothermal fluid, rather than trying to take water samples that must be analyzed chemically in the lab. Those samples usually involve collecting seawater using bottles with mechanical parts that are likely to be clogged by hot, caustic fluids produced by fluid near seafloor volcanoes and can only collect a very limited number of samples. An optical sensor could take measurements continually.
