New Ocean Floor Just Before and After Creation

A multidisciplinary research team from six institutions has for the first time successfully measured a seafloor eruption at its source along the global mid-ocean ridge, the most active volcanic system on Earth. The event along the East Pacific Rise has provided researchers from Woods Hole Oceanographic Institution (WHOI) with a rare opportunity to observe what happens in the immediate aftermath of an eruption. Ocean-bottom seismometers, which had been deployed by researchers from the Lamont-Doherty Earth Observatory (LDEO) of Columbia University, detected steadily increasing levels of earthquake activity over several years leading up to 2006. Research teams from WHOI and other institutions then used towed cameras and the submersible Alvin to make a visual confirmation of the seafloor eruptions. A research paper describing the seismic data was authored by Maya Tolstoy of LDEO and includes scientists from WHOI, the University of Hawaii, Brown University, the University of Washington, the University of Florida, and NOAA’s Pacific Marine Environmental Laboratory (PMEL). The findings will be published in an upcoming issue of Science, though a preliminary analysis was released on 23 November 2006 on the Science Express web site.



In 2003, the LDEO team deployed a dozen seismometers on the ocean floor along the East Pacific Rise (EPR), near 9°50’ N latitude, about 400 miles south of Acapulco, Mexico. Each year when they returned to service the instruments, the researchers detected steadily increasing levels of earthquake activity as magma moved beneath the ridge axis. They suspected a major seismic event was imminent. Sometime between May 2005 (the last readout of the seismometers) and April 2006, a series of volcanic eruptions paved over areas of the ocean floor. A scheduled expedition on the WHOI-operated Research Vessel (R/V) Knorr in April 2006 provided the first hint of an eruption. The LDEO team discovered that most of their instruments could not be recovered and surmised that a seafloor eruption had probably wiped them out. in May 2006 on the R/V New Horizon (operated by the Scripps Institution of Oceanography) to survey the ridge axis and to measure and sample the water above the eruption site. WHOI marine geologist Dan Fornari and biologist Tim Shank used a towed camera system to make the first visual confirmation of the new eruption along the EPR, observing fresh lava and noting that several seafloor biological communities that had once thrived were now gone.