Volcanoes like krakatau and Mount St. Helens are famous for their destruction, but studies at a unique undersea observatory are revealing a much less familiar, nurturing side to eruptions.
Scientists with the New Millennium Observatory, monitoring the ocean bottom 290 miles off the Oregon coast, hit pay dirt in 1998, when Navy hydrophones picked up loud rumblings of the Axial Volcano. A massive outpouring of lava rose up to fill a scar formed where the Pacific Ocean is pulling away from North America, while Axial's crater sank by about 10 feet as part of a process that perpetuates the constant drifting of the continents by creating new ocean floor. A fleet of submersible vehicles, tethered robots, and automatic cameras has gathered data ever since the eruption transformed the landscape nearly a mile down.
|All photographs NOAA Vents Program |
The eruption also created an unprecedented opportunity for scientists to continuously observe a startling sequence of ecological changes. Even as lava overran old life at the bottom, jets of water squeezed out by the volcano disgorged bacteria that thrive at 220 degrees Fahrenheit--hotter than household boiling water--from even more searing environments below. Despite the complete lack of sunlight, bacterial colonies bloomed around Axial, feeding on volcanic chemicals like hydrogen sulfide, and tube worms arrived seemingly from nowhere. Such scenes of rebirth are probably common along the 40 thousand miles of mid-ocean ridges, where the Earth's crust is torn apart. It will take years for scientists to digest Axial's lessons about the long-hidden connection between undersea volcanoes, the biosphere, and our planet's geological evolution. "We have more direct observations of eruptions on Io than on the seafloor," says geologist Robert Embley of NOAA's Pacific Marine Environmental Laboratory in Oregon, who led two of the expeditions around Axial. "This is a whole hidden world."
|When lava from Axial Volcano covered older flows on the seafloor (above), there was an eruption of life. Sulfur-eating bacteria nourished new organisms that promptly moved in |
| ||1) tube worms |
| ||2) tube and palm worms |
| ||3) a scaleworm |