First views of an underwater eruption
When the National Science Foundation's Ridge 2000 program was launched in the late 1990s to study active undersea volcanic activities, researchers chose several areas of interest. One of those is located about 400 miles west of Mexico along a massive volcanic mountain range called the East Pacific Rise. When the U.S. researchers returned to check their seismometers in April 2006, they discovered that several of them were lost, buried under new lava from an underwater eruption. And when they used a deep-diving camera system to see what's had happened, they saw that almost ocean bottom life had disappeared. As says one of the scientists, this was like seeing the 'death and birth of a mid-ocean ridge from all perspectives -- geological, biological, geophysical.' But read more...
Here is a short excerpt from a University of Florida news release.
A combination of luck and being in the right place at the right time allowed a University of Florida geologist and other scientists to capture and record an undersea volcanic eruption for the first time ever. "Never before have we had instruments in place like this that recorded an eruptive event on the seafloor," said Mike Perfit, a UF professor of geology.
But the project was headed by Maya Tolstoy, a marine geophysicist at Lamont-Doherty Earth Observatory of Columbia University, which also published a news release about the event, "Scientists Lose Instruments, Gain First Look at Seafloor Formation." And here is the story of the lost seismometers.
Tolstoy and Lamont-Doherty colleague Felix Waldhauser set an array of ocean bottom seismometers along a section of the East Pacific Rise off the coast of Mexico in 2003 to study the little-understood process of seafloor spreading — a process that is responsible for the formation of nearly three-quarters of the Earth's crust. When a team went back in April 2006 to retrieve the instruments, however, only four out of 12 responded to the coded release signal and bobbed to the surface; three more responded to the signal, but did not come up. The rest remained silent.
Below is an illustration showing the location of the seismometers. "When researchers went to retrieve 12 ocean bottom seismometers placed along the East Pacific rise to monitor for submarine eruptions, they found most of the instruments were trapped in fresh lava or unresponsive." (Credit: Nicolle Rager-Fuller, NSF).
After measuring the temperature and salinity and turbidity near the bottom of the ocean, the team concluded that there were signs of a recent volcanic eruption. And they asked another research vessel equipped with deep-diving cameras to come and check what was going on.
Below is a picture taken with a deep-diving camera system during the April/May, 2006 R/V New Horizon cruise. On this photo, the new lava flow appears dark while an older flow is lighter (Credit: Dan Fornari, Woods Hole Oceanographic Institution; Jim Cowen, U. of Hawaii, and the TCS06NH science party). Here is a link to a larger version.
When the group realized that their instruments have been so close from an underwater eruption, "they celebrated their fortune -- no one has ever closely recorded the series of micro-earthquakes associated with the formation of new seafloor."
And they described their findings in a paper published by Science Express, Science's online magazine, under the name "A Seafloor Spreading Event Captured by Seismometers" (November 23, 2006). Here is a link to the abstract.
For more information, you can visit this Ridge 2000 page about how the researchers discovered and documented the seafloor eruption. There is even a link to a 178 MB QuickTime 3-D visualization.
Sources: University of Florida news release, via EurekAlert!, November 23, 2006; Lamont-Doherty Earth Observatory News, November 23, 2006; and various websites
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