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Images: Undersea Asphalt Volcanoes Discovered

Ed Keller, a scientist at the University of California, Santa Barbara, looked at sonar maps collected by the Monterrey Bay Aquarium Research Institute and first noticed mysterious mounds poking out of the seafloor off Santa Barbara. He offered theories of what they were in a paper published in 2007.
(Edward A. Keller, University of California, Santa Barbara)

In 2007, UCSB scientist Dave Valentine (right) and WHOI scientist Chris Reddy investigated the largest mound in the submersible Alvin. Using Alvin's manipulator they brought back a large sample of rock from the undersea dome called Il Duomo.They could heft it easily because it was made of asphalt, the solidified residue of oil. (Molly Redmond, University of California, Santa Barbara)

The WHOI undersea vehicle Sentry collected sonar data to create this map of the undersea asphalt mound called Il Duomo, the largest of seven similar domes in the Santa Barbara Channel. It covers twice the area of a football field and rises 30 meters, or six stories, above the seafloor. The scale at right is in meters below the sea surface. (ABE/Sentry Group, Woods Hole Oceanographic Institution)

The area around Santa Barbara is very geologically active, because of the movement of the San Andreas and other faults. Extensive faulting or rupturing in the Earth allows oil and gas from subterranean reservoirs to seep up to the seafloor and ultimately into the ocean and to the atmosphere. But some oil solidifies to create asphalt volcanoes. (Jack Cook, Woods Hole Oceanographic Institution)

Samples of asphalt collected from the seafloor with Alvin had many cylindrical holes that looked like they were made by drills. See photo below.
(Molly Redmond, University of California, Santa Barbara)

Reddy and Valentine think the holes may have been made by worms that bored into the relatively soft asphalt to hide from predators. (Molly Redmond, University of California, Santa Barbara)