Category: General Article
Friday August 14, 2015
Submitted by Rachel Teasdale
Summary: Today all teams are working to get ready for our arrival at Axial Seamount on Saturday afternoon.
Friday morning, we had a safety meeting at 8:00 a.m. to learn what to do in the unlikely event of a fire or other emergency and practiced putting on our immersion suits. (See the video in the right sidebar entitled Ready, Set, Suit Up for details on these suits.)
By 9:00 a.m. we were untied from Pier 90 and headed north through Puget Sound in calm water and light rain. The science crew is busy getting instruments ready for first deployments on Saturday afternoon when we arrive at Axial Seamount. At 10:00 this morning we did our first Skype call to the Hatfield Marine Science Center to talk to a great group of kids in a Marine Science Camp. The rest of the day will take us through the Strait of Juan de Fuca and then out into the Pacific Ocean and approximately 400 miles (640 km) to Axial Seamount where we’ll be able to get started on a busy suite of activities to meet a variety of science goals.
Our 2015 Axial Seamount Expedition includes three interrelated scientific investigations led by four principle investigators (called PIs for short) who collaborate with a variety of scientists and institutions prior to, during, and following the cruise. Each project has specific scientific goals for the cruise, all of which are related to the unique environment of Axial Seamount.
1. Seafloor pressure measurements to measure volcanic inflation and deflation:
This investigation is headed by PIs Scott Nooner and Bill Chadwick. This work employs multiple instruments that precisely determine the depth of the ocean floor at Axial Seamount to look for vertical movements due to volcanic activity. Volcanoes like Axial Seamount inflate and deflate like a balloon. If magma accumulates below the seafloor, the seafloor will rise (inflation) and during an eruption the seafloor will sink (deflation).
Nooner and Chadwick have recorded progressive inflation and deflation events for the last 15 years at Axial Seamount using monitoring instruments Called Bottom Pressure Recorders (BPRs).
In addition, it was recently demonstrated by colleagues at the Monterey Bay Aquarium Research Institute (MBARI) that high-resolution mapping by Autonomous Underwater Vehicles like Sentry also measure these kinds of vertical movements of the seafloor by repeat surveys. On this cruise Sentry will be collecting mapping data both to measure inflation and deflation, and to make detailed maps of Axial Seamount’s newest lava flows.
2. Collect samples and incubate hydrothermal vent fluids for chemical and microbial analysis:
This investigation is headed by PIs Dave Butterfield, Julie Huber, and Jim Holden. This is a mouthful to say, but basically it involves samples of seawater above and around the hydrothermal vents being collected in a CTD, which is a collection of instruments that measure Conductivity (to calculate water salinity), Temperature, and Depth. The CTD houses multiple bottles so that water samples can be collected on command as the instrument package travels vertically through the water column. Water samples will be collected outside the area of volcanic activity to determine “background” conditions, which can then be compared with samples closer to the hydrothermal vents, the caldera, and new lava flows.
Additional water samples and microbes will be collected at hydrothermal vents on the seafloor using a collection of tools housed on the Jason ROV. Hydrothermal microbes are single celled organisms that live off of the chemical energy from different sources of “food,” such as hydrogen (H2), hydrogen sulfide (H2S), and methane (CH4). To collect samples, fluid samplers (like large syringes) suck water from hydrothermal vents into a series of bottles. The water chemistry and microbial organisms that live in and around the hydrothermal vents help to better understand the organisms present and the environmental conditions in which they can survive.
3. Event response activities related to the April-May eruption:
All the PIs are involved in this one. In the early hours of April 24, seismometers installed at Axial Seamount started to record thousands of small earthquakes at the same time that Bottom Pressure Recorders detected a sharp drop in the seafloor, both of which signaled that an eruption was occurring at the volcano. This was recognized almost immediately because of the recently installed Cabled Array monitoring network of the National Science Foundation’s (NSF) Ocean Observatories Initiative that is now sending data back to shore. New samples of the 2015 lavas will be collected and the new flows will be mapped by Sentry with multi-beam sonar to better understand the volume and extent of the 2015 eruption. Vent fluid and microbe samples from the young lavas will help show how eruptions change the hydrothermal vents and biological communities. The timing of the 2015 Axial Seamount Expedition is a unique opportunity to investigate the most recent eruption and document the state of a submarine volcano in its aftermath.
Related Features: Explore By Ecosystem: Marine Trenches
Photo and video courtesy of Axial 2015 Team.