A series of minor earthquakes in Yellowstone National Park in 2021 triggered significant changes in the deep subsurface environment, boosting microbial activity. Researchers found that the seismic events altered water chemistry and increased microbe populations in a borehole near Yellowstone Lake. These shifts highlight how geological activity can sustain life in dark, isolated underground habitats.
In 2021, a swarm of small earthquakes shook the Yellowstone Plateau Volcanic Field, prompting Eric Boyd and his team to investigate their effects on subsurface microbial ecosystems. These microbes thrive in deep rock and water systems, far from sunlight, by harnessing energy from chemical reactions as water flows through fractured rock.
The earthquakes disrupted this environment by exposing new rock surfaces, releasing previously trapped fluids, and altering water pathways. This led to fresh chemical reactions, effectively changing the available energy sources—or the 'chemical menu'—for the microbes.
To capture these changes, the researchers sampled fluids from a borehole about 100 meters deep on the western edge of Yellowstone Lake. They collected samples five times during 2021, tracking immediate and longer-term responses. Post-earthquake analyses revealed elevated levels of hydrogen, sulfide, and dissolved organic carbon in the water—key energy compounds for subsurface organisms. Planktonic cell counts also rose, signaling a surge in microbial presence within the water column.
The study further documented shifts in microbial community composition. Unlike the typically stable populations in continental bedrock aquifers, Yellowstone's underground life responded rapidly to the seismic energy, altering both geochemical and biological profiles.
Published in PNAS Nexus in 2025, the research by Boyd and colleagues, including Daniel R. Colman and Ana Menchaca, suggests these dynamics could be common in seismically active regions worldwide. Such processes may sustain microbial life in extreme Earth environments and inform habitability on water-rich rocky planets like Mars.