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Dormant asphalt volcanoes found on sea floor off Santa Barbara

April 27, 2010 |  7:07 pm

Scientists have discovered a cluster of underwater asphalt volcanoes rising from the sea floor just off Santa Barbara.

The seven dormant volcanoes, some as tall as six-story buildings, probably last disgorged petroleum and natural gas into the surrounding water during the most recent Ice Age about 30,000 years ago, according to geochemist David Valentine of UC Santa Barbara.

Valentine and his fellow researchers first discovered the asphalt behemoths in 2007 using a U.S. Navy submarine operated by the Woods Hole Oceanographic Institution.

They explored them over two years in expeditions funded by the National Science Foundation. Located as shallow as 700 feet below the surface, some of the mounds have craters, methane leaks and brittle sheets of hardened asphalt flows.

The region is about 10 miles from the coast. Researchers had previously found evidence of methane-gas release in the area. The methane fostered bacteria that leached oxygen out of the water and created a dead zone. The volcanoes may be one culprit, Valentine said.

-- Jill Leovy

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