MBARI's research vessel Western Flyer and the remotely operated vehicle Doc Ricketts are at sea in the Pacific Northwest, where MBARI scientists are studying underwater volcanoes, midwater animals, and methane hydrates in the seafloor. The public can follow this expedition through daily reports from the ship.
Leg 4 - Submarine Volcanism I
August 16 - 25, 2009
Leg #4 of this expedition focuses on sampling at Axial Volcano on the Juan de Fuca Ridge and at one of the Vance Seamounts nearby.
The first objective is to sample the pyroclastic deposits that blanket the summits and are exposed at the rims of the large calderas of the two volcanoes. The thick deposits should record the entire sequence of eruptions since the calderas formed. We plan to use the vibracorer to sample the entire section at each volcano to determine if the calderas collapsed in a single, cataclysmic event or as a series of smaller eruptions, determine the timing of the collapse, and discover how the clasts formed and were deposited.
The second objective is to collect young and old flows inside and on the rim of Axial caldera. We will use high-resolution bathymetry recently acquired by the Mapping AUV to guide our ROV dives. Axial Volcano erupted most recently in 1998 with a vigorous flow at the southern end of the caldera that overran older, perhaps more voluminous flows. ROV observations of this and the other, well-mapped flows, and advances we are making in age-dating of the collected samples, will improve our understanding of the history of Axial Volcano: of timing, volumes, and emplacement styles of volcanic events.
Other objectives are to sample hydrothermal fluids using a newly designed sampler for continued monitoring of the hydrothermal systems at Axial and comparison with those at Loihi Seamount, Hawaii; and to collect hydrothermal vent animals for genetic analysis to assess dispersal and isolation of vent populations.