Scientists from the Yellowstone Volcano Observatory recently conducted a detailed study of the new thermal area near Tern Lake in Yellowstone National Park, offering insights into the development of these dynamic geothermal features. The team, including geochemist Sara Peek from the U.S. Geological Survey, aimed to measure gas emissions and temperatures, providing a clearer understanding of how thermal areas evolve.
Thermal areas are regions where heat from Yellowstone’s magmatic system reaches the earth’s surface. These areas vary widely in age and activity, with some, like Brimstone Basin, cooling off, while others, like the new Tern Lake area, are quite active. The Tern Lake thermal area was first detected using satellite data and has been monitored through aerial and satellite imagery.
During their initial visit in 2019, Yellowstone Volcano Observatory scientists identified signs of geothermal activity, including dead trees, hot ground, steam emissions, and sulfur deposits. A follow-up visit focused on measuring the total amount of volcanic gas released and analyzing its composition.
Using a CO2 flux meter, the team measured gas emissions across a grid of GPS points, finding that the new thermal area emits approximately 12.4 metric tons of CO2 per day. This is about half the emission rate of the nearby Mud Volcano thermal area but only a fraction of the total emissions from Yellowstone’s thermal regions.
Temperature measurements showed boiling temperatures (92°C or 198°F) just below the ground surface at many sites within the core of the thermal area, correlating with the highest CO2 emissions. These high temperatures are attributed to gas, primarily steam, carrying heat from below.
Gas samples revealed that steam and CO2 are the primary emissions, with minor amounts of hydrogen sulfide (H2S), methane (CH4), nitrogen, oxygen, and other trace gases. The new thermal area displayed higher nitrogen and lower H2S levels compared to the nearby Fern Lake thermal area, suggesting more air incorporation and differing deep gas compositions.
As the Tern Lake thermal area evolves, gas emissions and temperatures are expected to become more concentrated, leading to the formation of fumaroles and changes in the landscape. Continuous monitoring and comparison with mature thermal areas provide valuable insights into these geothermal processes.
