Sampling Hydrothermal Gases on Vailuluʻu Seamount

While exploring Vailuluʻu Seamount (the only active underwater volcano within the National Marine Sanctuary of American Samoa), we used ROV Hercules to bring special sampling equipment to the seamount’s active vents. These Isobaric Gas-Tight (IGT) Samplers are designed to collect fluids and preserve them at the high-pressure conditions of the seafloor. This ensures that the chemical characteristics of the fluid (including dissolved gases like carbon dioxide) are not modified before laboratory analyses. The materials spewing from these chimneys are corrosive, high temperature, and high pressure. Still, our pilots were able to successfully use the IGT tools without harming the more sensitive parts of the ROV. 

By studying these gases, scientists can determine the characteristics of the reactions between the hydrothermal fluid and underlying rocks, including temperature, depth within the crust, and chemical transfer between rocks and fluids. This helps geologists understand the inner workings of the volcano and biologists evaluate how vent ecosystems are able to thrive and survive at these sites. Learn more from project lead Dr. Santiago Herrera in this highlight video.