East Diamante: A Hydrothermal Hotbed
February 18, 2003
Pacific Marine Environmental Laboratory, NOAA
Our exploration of Mariana Arc submarine volcanoes continues to find previously unknown sources of hydrothermal activity. Some 50 underwater volcanoes are strewn along the Mariana Arc, but only a very few have been searched for active venting. The accompanying figure shows the exciting results at one volcano, called East Diamante. This volcano, lying 20 nautical miles south of the island volcano Anatahan, is an old caldera (large crater) with a volcanic dome in the center.
We conducted a CTD tow-yo beginning outside the caldera (at the left-hand side of the figure, near 145.63 degrees E). No hydrothermal signals were obvious there, but as the tow progressed over the rim of the caldera and descended inside, we detected increasingly intense plumes. The plumes appear centered around the central volcanic dome, suggesting that volcanic activity has occurred there recently. The image shows at least three distinct plume layers, centered near 350 m, 275 m, and 200 m. These multiple plume layers require multiple sources, either at different depths or with different buoyancy energies, that carry the plumes to corresponding heights above the sea floor.
This site should be a prime target for the next phase of the Submarine Ring of Fire project, when we return with a remotely operated vehicle (ROV) to sample the fluids, minerals, and biology of these new vent fields.