Nearly a third of Earth’s living mass exists underground, in dark environments where sunlight never reaches.
Instead of relying on photosynthesis, these deep-living microbes survive on chemical energy produced when water interacts with rocks. But what happens when the ground itself starts to move?
A new study suggests that earthquakes can dramatically reshape life beneath the surface—at least in one of the planet’s most active landscapes: Yellowstone.
In research published in PNAS Nexus, a team led by Eric Boyd studied how a swarm of small earthquakes in 2021 changed the chemistry and microbial life in a borehole near Yellowstone Lake.
The borehole stretches nearly 100 meters deep and provides a rare window into the hidden world below Yellowstone’s volcanic plateau.
Earthquakes do more than shake the ground. They can crack open rocks, change the direction of flowing water, and release trapped gases and fluids.
These disturbances can expose fresh rock surfaces, creating new opportunities for chemical reactions that fuel underground microorganisms. Essentially, earthquakes can refresh the energy supply for deep subsurface ecosystems.
To understand this process, researchers collected water and fluid samples from the borehole five times throughout 2021.
After the earthquake swarm, they noticed a clear spike in chemicals that microbes can use for energy—such as hydrogen, sulfide, and dissolved organic carbon. These changes in chemistry were followed by a rise in the number of free-floating microbial cells.
Not only did the number of microbes change, but the types of microbes also shifted. This is unusual because underground microbial communities, especially those living in deep rock aquifers, tend to be stable and slow-changing.
But in this case, the microbial populations evolved over time, responding to the new chemical conditions created by the seismic activity.
The study suggests that the kinetic energy released by earthquakes can directly influence the underground environment by altering the chemistry of aquifers and reshaping the microbial community.
These changes reflect a complex, dynamic relationship between geology and biology—one that is rarely seen but fundamental to understanding life beneath the Earth’s surface.
What makes the findings even more intriguing is their relevance beyond Yellowstone. The same geological processes could occur anywhere with active seismic activity, including other planets. On Mars, for example, quakes and water–rock interactions might similarly create temporary bursts of chemical energy that could support microbial life.
By showing how earthquakes can renew and reshape deep ecosystems, this study expands our understanding of how life survives in extreme environments—and how it might persist on worlds far beyond our own.
