The red arc of seamounts shows the Mariana volcanoes under study. The dark blue color indicates the Mariana trench, the deepest place on the planet.

Latest expedition:

NOAA Vents scientists recently confirmed that NW Rota-1 submarine volcano in the Mariana Arc is still erupting and experienced a major landslide since it was last visited in 2009.  See the 2010 cruise blog for more information, images and video clips from this year's ROV dives.
2010 cruise to NW Rota-1

2009 Expedition: This expedition to NW Rota-1, (one year later) with the ROV Jason made observations of the activity, collected samples, and deployed instruments. The activity in 2009 was distinctly different than in 2010..

The Mariana Volcanic Arc extends from 13°N to 23°N in the western Pacific Ocean, northwest of Guam. The Marianas region contains 9 volcanic islands more than 50 submarine volcanoes over a distance of more than 1000 km. The summits of these submarine volcanoes range from 50 m to more than 1800 m below sea level. The Marianas is one of the most active volcanic arcs on Earth.

In February 2003, the Vents Program conducted an extensive survey of the submarine volcanoes in the Mariana Arc (funded in part by NOAA's Ocean Exploration Program). This expedition included detailed mapping of the seafloor and a search for indications of hydrothermal venting at each volcano. It was found that about 20% of the Marianas submarine volcanoes were hydrothermally active. Follow up expeditions with remotely operated vehicles have investigated many of these sites on the seafloor. (See summary paper by Embley et al., Exploring the Submarine Ring of Fire (pdf), 2007.)