10:26 PM PDT on Thursday, May 25, 2006

By FRANK MUNGEAM, kgw.com Staff

The geology of the Mariana arc, which includes Saipan and Iwo Jima as well as Guam, is similar to that of the Cascade Mountain Range of the Pacific Northwest and provides clues to terrestrial volcanic activity.

Mount St. Helens, for example, lies within the Cascades. Both are on the Pacific "Ring of Fire" and, in each case, an oceanic plate is being subducted beneath another plate, causing a string of volcanoes above where the plate begins to melt. The deep-sea vents located near the undersea volcanoes may also harbor clues to the origin of life on Earth, many scientists believe.

(NOAA)

While much of the focus has been on Rota, because of its recent volcanic activity, the researchers have surveyed more than 50 submarine volcanoes in the Mariana arc. At some of the sites they observed in 2004 using an ROV, they discovered black "smokers" - chimneys made from spewing minerals and hydrothermal vents. Most such vents are deep in the ocean, but they found some on the shallow summits of volcanoes with schools of tropical fish, tuna and sharks swimming nearby.

"As the ROV came closer to the surface, where the sunlight was able to penetrate, it was just a riot of life with incredible amounts of fish and corals," Chadwick said. "But what was truly unique was that two fundamentally different kinds of ecosystems were overlapping here - one based on sunlight and one based on chemicals."

Mount St. Helens, for example, lies within the Cascades. Both are on the Pacific "Ring of Fire" and, in each case, an oceanic plate is being subducted beneath another plate, causing a string of volcanoes above where the plate begins to melt.

The deep-sea vents located near the undersea volcanoes may also harbor clues to the origin of life on Earth, many scientists believe. While much of the focus has been on Rota, because of its recent volcanic activity, the researchers have surveyed more than 50 submarine volcanoes in the Mariana arc. At some of the sites they observed in 2004 using an ROV, they discovered black "smokers" - chimneys made from spewing minerals and hydrothermal vents. Most such vents are deep in the ocean, but they found some on the shallow summits of volcanoes with schools of tropical fish, tuna and sharks swimming nearby.

"As the ROV came closer to the surface, where the sunlight was able to penetrate, it was just a riot of life with incredible amounts of fish and corals," Chadwick said. "But what was truly unique was that two fundamentally different kinds of ecosystems were overlapping here - one based on sunlight and one based on chemicals."

Read more about the undersea volcano study