March 27, 2010

Eruption movies

Yesterday we got the clearest views yet of the explosive eruptive activity at NW Rota. We've now found 5 separate eruptive vents, all in a line within about 100 m. Some have opened up while we've been out here. The activity we've seen this year is a lot more variable than we've seen in the past. An eruptive vent will be active on one dive, then inactive on the next. Vents even open up and shut down from hour to hour. We don't really understand why, but suspect that the volcanic plumbing system was disturbed by the landslide and has not yet finished reorganizing itself.

With each explosive burst rocks and ash are thrown up (making the plume dark), but quickly drop back to the seafloor (turning the plume white). The billowing white plume is full of tiny droplets of molten sulfur.

As the clouds from an explosive burst rise and expand, bubbles of CO2 float upward in front of Jason. Plumes of such bubbles are what we've been seeing with the Kilo Moana's new sonar system (see Volcano Mapping post).

Because the pressure at this depth dampens the power of the explosions, Jason can approach within a few feet of the eruptive vent (notice the Jason basket in the foreground at the beginning of this clip). However, in this case the volcano got a little too active and Jason had to back away temporarily. Notice how the eruptive plume expands and contracts during the biggest bursts.

-Bill Chadwick, Oregon State University

All video copyright by Advanced Imaging and Visualization Lab WHOI