Yellowstone earthquakes may influence more than the rocks beneath the famous national park. New research suggests that seismic activity can alter underground water chemistry in ways that temporarily increase the chemical resources available to microbes. In a 2025 study, researchers tracked an aquifer nearly 100 meters below Yellowstone and found that periods of stronger seismic activity coincided with increases in hydrogen, sulfide, dissolved organic carbon, and microbial cell concentrations. However, the evidence does not show that earthquakes directly “feed” underground organisms. Instead, it points to a more complex process in which shaking may change water pathways, fracture rocks, expose fresh mineral surfaces, and release or generate chemicals that microbes can use.
How Yellowstone earthquakes can change the underground environment
Life below Earth’s surface operates under very different conditions from ecosystems exposed to sunlight. Instead of relying mainly on photosynthesis, many subsurface microorganisms obtain energy from chemical reactions involving substances such as hydrogen, sulfur compounds, carbon dioxide, and other inorganic materials. These organisms include chemolithotrophic microbes, which can use chemical reactions involving inorganic compounds to support growth.
However, chemical resources underground are not necessarily unlimited. Microorganisms consume available compounds, while geological processes continually influence how those compounds form, move, and interact. Therefore, researchers have long investigated how subsurface ecosystems can remain active over extremely long periods despite their isolation from surface sunlight and organic matter.
This is where Yellowstone earthquakes become scientifically interesting. Earthquakes can fracture and deform rocks, potentially changing the routes through which groundwater moves. In addition, mechanical breaking of rock can expose fresh mineral surfaces and release substances trapped within pores, inclusions, or mineral structures. Some reactions between freshly exposed rock and water can also generate hydrogen.
The 2025 study led by researchers from Montana State University examined whether these geological changes could affect microorganisms living in Yellowstone’s subsurface waters. Importantly, the researchers did not assume that earthquakes automatically create a microbial food supply. Instead, they tested whether seismic energy and changes in underground chemistry occurred together.
Their findings supported that connection. As seismic activity increased during the study period, several chemicals associated with microbial metabolism also changed. Consequently, the researchers proposed that earthquakes may periodically refresh chemical conditions that support underground microbial communities.
What researchers found 100 meters beneath Yellowstone
To investigate the relationship directly, scientists collected samples from a borehole near the West Thumb of Yellowstone Lake. The borehole intersects an aquifer within rhyolitic bedrock, allowing researchers to examine underground water and the microorganisms living within it.
The team collected samples five times between May and November 2021. During that six-month period, Yellowstone experienced roughly 2,000 earthquakes, including notable earthquake swarms in May–June and July. Rather than simply counting earthquakes, the researchers examined the seismic energy absorbed near the sampling location and compared it with changes in water chemistry and microbial communities.
The results revealed several striking patterns. Concentrations of hydrogen, sulfide, and dissolved organic carbon increased during the period when seismic energy was rising. Hydrogen reached concentrations of roughly 27–44 micromoles per liter in the samples, which the researchers noted were about 10–20 times higher than the highest concentrations previously measured in Yellowstone’s thermal and nonthermal waters.
At the same time, the number of microbial cells increased substantially. The study reported cell concentrations rising from approximately 1.28 million cells per milliliter at the first sampling point to more than 8 million cells per milliliter later in the study. That represents a major change in the sampled microbial population.
The researchers also detected changes in microbial groups associated with hydrogen-based metabolism. In particular, populations related to Dethiobacteraceae and Desulfotomaculum increased during parts of the period when hydrogen and other relevant chemicals became more abundant.
However, the pattern changed when seismic activity declined. Hydrogen, sulfide, and microbial cell concentrations subsequently decreased. Therefore, the observations establish a temporal association between seismic activity, geochemical changes, and microbial responses. They do not, by themselves, prove that earthquakes directly caused every biological change observed in the aquifer.
Why fractured Yellowstone rock could provide microbes with new resources
The researchers also investigated whether the rocks themselves could help explain the chemical changes. Yellowstone’s subsurface near the study site contains rhyolite, a volcanic rock that can interact with groundwater.
In laboratory experiments, the team mechanically crushed rhyolite samples and examined the chemicals released from the material. The experiments showed that crushing and subsequent exposure to water could release organic carbon and hydrogen and could generate additional hydrogen.
This result provides a plausible mechanism connecting earthquakes with microbial chemistry. When seismic activity fractures or crushes underground rock, it can increase the amount of fresh mineral surface exposed to water. At the same time, fractures can alter groundwater pathways and potentially release chemicals that were previously trapped within the rock.
For microorganisms capable of using hydrogen or other chemical compounds, those changes can create new opportunities for energy production. In other words, the earthquake itself does not function like a biological food source. Instead, seismic activity can modify the geological and chemical environment in which microbes obtain energy.
The researchers found evidence consistent with this process in the Yellowstone aquifer. As seismic energy accumulated, hydrogen and other compounds increased, while microbial populations changed at the same time. The laboratory experiments strengthened the geological explanation by showing that mechanical treatment of rhyolite can release or generate chemicals relevant to microbial metabolism.
Nevertheless, scientists still need to determine exactly how much of the observed chemical change came from rock fracturing, altered groundwater movement, release from pores and inclusions, water-rock reactions, or combinations of these mechanisms. The study itself presents these processes as possible explanations rather than claiming that one mechanism has been definitively established.
That distinction matters because underground ecosystems are complex. Several geological and biological processes can operate simultaneously, and a change in one part of the system can influence many others.
What the findings mean for underground life on Earth and Mars
The Yellowstone results provide a new perspective on how microbial ecosystems can respond to geological activity. Subsurface microbes do not necessarily live in chemically static environments. Instead, earthquakes and other geological processes may periodically modify the availability of energy-producing chemicals.
The study therefore suggests that seismic activity could contribute to maintaining chemical conditions that support microbial communities over long periods. However, researchers have not demonstrated that earthquakes are essential for the survival of Yellowstone’s underground microbes. Other processes, including water-rock interactions and radiolysis, can also generate chemically useful compounds in Earth’s subsurface.
The findings could nevertheless have implications beyond Yellowstone. If earthquakes can influence microbial habitats through rock fracturing and chemical changes, similar processes might operate on other rocky worlds. Mars is particularly interesting because spacecraft have detected evidence consistent with water-related environments beneath or within the Martian crust, while Mars also experiences seismic activity known as marsquakes.
Yet this does not mean that scientists have discovered life on Mars. Nor does the Yellowstone study demonstrate that Martian earthquakes currently support microorganisms. Instead, the research provides a geological mechanism that scientists can consider when evaluating possible subsurface habitats on other planets.
Future missions capable of sampling deeper underground environments could therefore test questions that surface rovers cannot easily answer. If microorganisms exist beneath another rocky planet, their survival may depend not only on the presence of water but also on whether geological processes continually create usable chemical energy.
For now, Yellowstone offers an unusually accessible natural laboratory. Its combination of volcanic geology, groundwater, earthquakes, and microbial ecosystems allows scientists to study how Earth’s physical processes interact with life beneath the surface. The new evidence makes that relationship more intriguing, while also showing why scientists must distinguish between a promising mechanism and a proven explanation.
Original Article: USGC
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