A new article published November 25th in Proceedings of the National Academy of Sciences (PNAS) Nexus reveals that earthquake activity may play a critical role in sustaining microbial life deep beneath Earth’s surface—an insight with implications for understanding the origins of life. Montana Technological University researchers Professor Alysia Cox and Dr. Eva Andrade-Barahona (Ph.D. Earth Science and Engineering, ‘25) are co-authors on the interdisciplinary study, which tracked geochemical and microbial changes in a Yellowstone aquifer during a months-long earthquake swarm.
The research team, led by Montana State University professor and microbiologist Dr. Eric Boyd, conducted detailed, sampling of fluids from a 100-meter-deep borehole near Yellowstone Lake. Their findings show that increased seismic energy corresponded with measurable shifts in the aquifer’s chemistry and microbial activity.
As earthquakes fractured the surrounding rhyolite bedrock, the process released hydrogen, dissolved organic carbon, and sulfide into the aquifer. These new chemical inputs acted as fuel sources for subsurface microorganisms, driving periods of increased metabolic activity and growth.
“When Eric contacted me about needing organic carbon and ∂13C analyses for his borehole and experimental project on subsurface microbial changes in Yellowstone and mentioned that they collected samples related to seismic activity, I got incredibly excited. We want to know how geochemistry and microbial communities change with seismic activity and Eric and his team captured that response,” Cox said. “I think this is one of the most significant contributions to collective knowledge I have ever been involved with partly because microbes form the basis of all ecosystems on Earth, up to half of Earth’s microbial biomass is in the subsurface and is fueled by energy stored in geochemical compounds. Earthquakes causing geochemical compounds to be released from minerals and the microbes fueling their metabolisms with these compounds helps explain how subsurface microbial communities can be sustained now, have been and evolved in the past, and how microbes could thrive on other planets in seismically active areas.”
Cox and Andrade-Barahona contributed analytical geochemical analyses to the project, measuring organic carbon and its carbon isotopic composition adding to the fluid chemistry, metals, and dissolved gases. Their work helped establish clear connections between seismic energy and shifts in aquifer chemistry—critical evidence showing that the subsurface biosphere responds rapidly to geological disturbances.
The study also included laboratory experiments in which the team mechanically pulverized Yellowstone rhyolite to simulate earthquake fracturing. These tests demonstrated that rock grinding can release or generate hydrogen and organic carbon, pointing to large subsurface reservoirs of chemical energy that seismic activity can unlock.
In Yellowstone’s seismically active environment—where up to 3,000 earthquakes occur annually—these processes may be key to sustaining deep microbial ecosystems that are isolated from the sunlight-driven energy sources found at Earth’s surface.
The findings open new avenues for understanding how microbial life persists in the deep crust over geologic time. They may also inform the search for life on other seismically active planetary bodies, including Mars.
This project brought together researchers from Montana Tech, Montana State University, the University of Colorado Boulder, the U.S. Geological Survey, New Mexico Tech, the National Park Service, and Princeton University.
The full article, “Seismic Shifts in the Geochemical and Microbial Composition of a Yellowstone Aquifer,” is available through PNAS Nexus. To accees, click here.