The tops of two active chimneys discovered at Niua South.

The tops of two active chimneys discovered at Niua South. Image courtesy of MARUM, University of Bremen and NOAA-Pacific Marine Environmental Laboratory. Download larger version (jpg, 1.1 MB).

Niua volcano proposed remotely operated vehicle dive sites indicated by black circles.

Niua volcano proposed remotely operated vehicle dive sites indicated by black circles. Image courtesy of Susan Merle, Oregon State University/NOAA Vents Program. Download larger version (jpg, 2.5 MB).

Active Chimneys
September 18, 2012

After two days of bad weather when we couldn't dive, the Quest 4000 ROV got back in the water today and made a dive at Niua South Volcano, the northern-most in the Tofua arc. The ROV explored a crater that was about 200 meters across and about 30 meters deep. At the center of the crater was a large sulfide mound, about 20 meters high and 50 meters wide, representing deposits formed during many years of high-temperature hydrothermal venting at this site. Most of the mound is now inactive but at the top we found a spectacular black-smoker vent, consisting of a cluster of about 20 active chimneys that had all grown together. The ROV sampled the vent fluids and gases coming out of the chimneys as well as a few pieces of the sulfides. Animals living at the vent included at least two species of shrimp, scaleworms, crabs, eelpouts, and barnacles.