Geological conditions in Yellowstone National Park during borehole microbiological study in 2021

Geological conditions in Yellowstone National Park during borehole microbiological study in 2021. Top panel (a) shows a map view of Yellowstone National Park, with different map colors representing water bodies and various rock types. Magenta dots represent the locations of earthquakes during April–November 2021, with the size of the dot corresponding to the strength of the earthquake (Julian Day is the number of the day within the year, so Julian Day 200, for example, was July 19, 2021). The borehole used to sample microbes during a six-month study period in 2021 is located at the south edge of Yellowstone Lake’s West Thumb and appears as a white dot. The bottom panel (b) is a cross-section of the borehole area, with colors representing how much fluid is contained in various layers. Known fluid pathways are designated by dotted lines. From Boyd et al., 2025 (https://doi.org/10.1093/pnasnexus/pgaf344).