A full day’s dive in volcano of Alarcón Seamounts
April 3, 2015
Jenny Paduan writes: The R/V Western Flyer departed last evening from Pichilingue Harbor near La Paz, Mexico. The weather was clear and warm and the sea was smooth as glass. We steamed through the night and arrived in time to do a full day’s ROV dive on the eastern-most volcano of the Alarcón Seamounts.
The dive began inside the 300-meter deep caldera of the volcano at a depth of 1,825 meters. Our priority here was to collect sediment that has accumulated on the caldera floor over time, as the caldera acts as a very effective sediment trap, preserving layers of sediment raining down from the sea surface over long periods of time. Our paleontologist colleagues will then analyze tiny marine animal shells, or foraminerifera, which have been deposited with the sediment. Past climate can be inferred from chemical analysis of the foraminifera shells.
The ROV ascended the wall of the caldera to its rim. Multiple lava flows that built the seamount are exposed in the caldera wall. At the very top, a thin deposit of volcaniclastic material (volcanic ash) is draped over the last lava flows from the volcano, testimony to the explosions it experienced as the flows ceased and the caldera collapsed. Further along we observed abundant, small growths of bacterial mats, which must be fueled by chemical-rich fluids flowing from small cracks or holes in the seafloor; this suggests that the interior of the volcano is still cooling.
Ronald Spelz writes: “Safety is our number one priority”, said the Western Flyer’s chief mate when we gathered in the wet lab during a mandatory safety briefing session. As soon as we heard these words, everyone nodded their heads and silently acknowledged that being out here on the ocean involves certain risks, and that in order to minimize these risks we all need to know the fundamentals of what to do and how to do it.
Scientists and crew members onboard the Western Flyer, no matter what, have to work hand-in-hand to assure that safety standards and regulations are met during all our operations, whether these are performed during transit, at dive sites, or even in port. Safety measures vary from the ordinary, such as wearing the proper safety equipment or staying clear during ROV and equipment launches and ensuring the functionality of the Western Flyer’s sanitation system, to the extraordinary, such as those to be performed during a fire or other emergency situation.
What we do scientifically is important, but doing it safely is vital!
—Jenny Paduan and Ronald Spelz