Geologists Dan Fornari and Susan Humphris will spend a sleepless night collecting rocks from what appears to be a large seafloor volcano on the axis of the Central Indian Ridge, located about 40 nautical miles south of the Edmond field.

Pulling their dredges from the Indian Ocean, they will look for fresh basalt, a glassy black rock that forms when hot volcanic lava hits icy seawater. The glassy basalt is a sign that the volcano has been recently active.

It is possible that this mountain on our maps is merely an uplifted block of crust but “the shape is a dead-ringer for an active submarine volcano,” said Dan.

Our bathymetric maps show that this volcano is 20 miles long and 10 miles wide, with an elevation of 4,264 feet (1300 meters) -- about a third of the height of Mount Rainier in Washington state. No other features of this type exist within hundreds of miles of our location on the Central Indian Ridge.

“Studying this volcano gives us more clues about how the mid-ocean ridge works,” said Dan.

Volcanoes form along Earth’s sixteen large and several small plates, which “float” on a partially molten layer below them. The plates’ movement and interaction is called plate tectonics. Periodically the plate boundaries pull apart, collide or slide past or beneath one another, triggering dramatic forces, such as earthquakes and volcanic eruptions.

We decided to head to the volcano tonight after ROV Jason’s depth sensor stopped working while collecting mussels and other vent animals at the Edmond field.

“It’s impossible to know where we are in depth with respect to Medea without it,” said ROV Jason’s Chief Pilot Will Sellers. It also limits our ability to collect samples or make close seafloor observations.

Medea is Jason’s teammate. It always hovers about 15 to 20 meters above Jason, absorbing the movements from the ship. Medea and Jason are connected by a 30-meter cable and need to maintain close contact for efficient operations on the seafloor.

Deeper Discovery

“When you think about it, it’s amazing that this maze of wires and sensors we call ROV Jason, connected to the ship by a 10 kilometer fiber optic cable, works at all,” said Dan. “We take technology for granted these days, and for the past month we’ve been used to going to work on the bottom of the ocean nearly every day as if it was routine.”

As a matter of fact, it is routine. Almost every day of the year, ROV Jason, Alvin or deep submergence vehicles operated by three other nations worldwide are exploring the seafloor.

For U.S. scientists, going to the depths of the ocean using Jason or in Alvin is routine, thanks to the innovative engineering and operational expertise of the National Deep Submergence Facility at Woods Hole Oceanographic Institution. They have been providing deep submergence capabilities for scientists and engineers for over 30 years.

Dive and Discover Water Word Puzzle [Click here for a printable version of Dive and Discover Water Word #2] Check back tomorrow for the solution.

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