In Yellowstone National Park, thousands of earthquakes occur each year, many too small for humans to feel. This high frequency of seismic activity has provided researchers with a unique opportunity to study the effects of earthquakes on underground ecosystems.
Montana State University professor Eric Boyd has published new research in PNAS Nexus examining how these frequent quakes affect some of Earth’s earliest lifeforms—microbes living beneath the surface. Boyd, who has spent over 20 years researching in Yellowstone as part of MSU’s Department of Microbiology and Cell Biology, said, “I think it’s one of the more significant findings that I have ever been a part of.” He explained that ancient microbial life likely originated underground about 3.8 billion years ago and depended on chemical energy stored in minerals. Over time, this energy would be depleted unless a process existed to replenish it.
Boyd’s research suggests that earthquakes play a key role by fracturing rocks and exposing fresh minerals for microbes to use. He noted that while seismic events are common globally, Yellowstone’s volcanic activity makes it an ideal location for such studies.
Jovanka Voyich, head of MSU’s Department of Microbiology and Cell Biology in the College of Agriculture, commented on Boyd’s work: “Eric’s investigation into how seismic activity shapes microbial communities in the Yellowstone ecosystem is yet another excellent example of his groundbreaking research exploring how microbial life persists and evolves in extreme environments. The fact that MSU undergraduate and graduate students can take courses and receive mentorship from one of the world’s most prestigious geobiologists is a remarkable educational opportunity.”
The study brought together data on Yellowstone’s subsurface systems—including earthquake records and analysis of underground microbes—to explore how early life could survive without sunlight or air. The project was supported by a $1 million grant from the W.M. Keck Foundation awarded in 2020.
According to Boyd, understanding how half or more of Earth’s microbial biomass survives underground may offer clues about evolution on our planet and possibilities for life elsewhere. “If you perturb a system, there will be a response. If you want to understand how our systems work, you need to understand those responses,” he said. “So much of the biomass on Earth is microbial, and if you eliminated that, there would be no higher forms of life. It’s as simple as understanding the food that sustains the microbes that sustain you.”
During fieldwork near Yellowstone Lake, Boyd observed increased sulfur gas levels during an earthquake swarm—a series of small quakes occurring close together—which coincided with changes in microbial populations within an aquifer. As seismic activity fractured rocks below ground, nutrients became more available for microbes; when the swarm ended, conditions returned to normal.
Boyd emphasized the importance of studying these processes: “Every single ecosystem on Earth is ultimately supported by microbes,” he said. “They are the base of all ecosystems as moderators of the geochemical cycles that sustain plant, animal and human health. If half of that base that sustains all life on Earth is in the subsurface, then you better understand how that microbial base has sustained itself.”
