Researchers have investigated how earthquakes impacted underground life in Yellowstone, where they thrive far from the Sun’s warmth and energy.
In a study published yesterday in the journal PNAS Nexus, a team studied how small earthquakes in 2021 influenced microbes in the rock and water systems beneath the Yellowstone Plateau Volcanic Field. These life forms draw energy not from photosynthesis but from the chemical reactions related to the movement of water through broken rock. The paper’s results could inform how life can exist in unexpected places and carry implications for the search for extraterrestrial life.
A change in chemical menu
“Seismic energy, like that released by earthquakes, can fracture rock and thereby alter subsurface fluid flow paths, release substrates from inclusions, and expose fresh mineral surfaces capable of reacting with water,” the team wrote in the study. All of these events can trigger “fresh” chemical reactions, as described in a PNAS Nexus statement, which modify the kinds of energy accessible to microbes. “However, it is unclear how such seismic-induced changes influence microbial communities.”
To address this gap, the researchers gathered water samples from a borehole (a human-made hole used for analyses) on the western edge of Yellowstone Lake five different times in 2021. This approach revealed a significant rise in hydrogen, sulfide, and dissolved organic carbon in the aftermath of the earthquakes—important sources of energy for numerous organisms living below ground. They also noted increased levels of planktonic cells. This indicates that the water column hosted more microbes than had been observed before the earthquakes.
These chemical and biological shifts suggest that the earthquake swarm temporarily increased the resources available to microbial life. What’s more, they documented a change in the types of molecules over time. This is particularly notable, given that researchers usually deem underground microbial communities in continental bedrock aquifers to be fairly stable. However, the subsurface system in question seemed to change rapidly and clearly in response to seismic energy.
Could this be happening on Mars?
The team concluded that earthquakes’ kinetic energy (energy related to motion) can impact the chemistry and biology of fluids in aquifers—underground areas of water-saturated rock that can pass water into wells and springs. Their results suggest that even small seismic occurrences can lead to significant changes in underground ecosystems.
Yellowstone isn’t the only region with regular seismic activity, so similar quakes elsewhere could trigger comparable changes to underground energy resources. If this process is widespread, it may help explain how microbes survive in deep, isolated environments.
What’s more, it carries implications for life beyond Earth. If a similar mechanism also takes place on other rocky planets with water, it might broaden our understanding of potential habitats for tiny extraterrestrials in places such as Mars.
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