Small quakes wake up deep life under Yellowstone

In 2021, a swarm of small earthquakes rippled beneath Yellowstone National Park and jolted a hidden ecosystem nearly 325 feet below the surface. Microbes living in a buried pocket of groundwater suddenly got a burst of energy.

A new study of fluids from that borehole shows that tiny quakes can reshape both the chemistry of the water and the mix of microbes living there.

Yellowstone’s deep community reacted fast, growing denser and more diverse as the ground shook. 

Yellowstone microbes respond to quakes

Up to 30 percent of Earth’s biomass may reside underground. These include microbes that survive in deep rock and sediment far from sunlight.

The work was led by Eric Boyd, a professor of environmental microbiology at Montana State University. His research centers on microbes that live in hot springs and deep rock.

Instead of photosynthesis, many of these microbes act as chemolithotrophs, organisms that gain energy by reacting dissolved chemicals, including hydrogen or sulfide.

Water flowing through fractured rock supplies those chemicals and keeps deep ecosystems operating. 

Quakes change Yellowstone water

Yellowstone’s 2021 quake swarm gave scientists an unexpected test case. A pre-existing monitoring well on the western shore of Yellowstone Lake taps a deep, fractured aquifer, an underground rock layer that stores and moves water. 

Researchers drew water from the well five times that year and measured both chemistry and DNA from the microbes.

Their paper links these changes to thousands of small earthquakes whose energy focused near the borehole.

During the most active part of the swarm, concentrations of hydrogen, sulfide, and dissolved organic carbon, carbon containing molecules dissolved in water that microbes can use, climbed in the sampled water. 

Those new ingredients reshaped the chemical options available to microbes living below Yellowstone.

In many deep continental aquifers, microbial communities remain steady over long periods. Yellowstone’s deep community shifted toward species that respond to fresh chemical energy after the crust slipped. 

Microbes recover differently

Subsurface microbes do not all bounce back at the same pace after a burst of seismic energy.

Some groups rebound quickly by using newly released hydrogen or sulfur compounds, while others return more slowly as conditions settle into a steady state again.

These recovery patterns offer clues about which metabolisms dominate when chemical supplies shift. 

The patterns also help clarify how long geological disturbances continue shaping underground ecosystems after the ground grows quiet.

Rocks release energy

To test where the extra energy came from, the team crushed pieces of Yellowstone rhyolite, the volcanic rock that hosts the aquifer.

They mixed the powder with water in the lab and found that the reaction released measurable hydrogen gas and additional dissolved organic carbon. 

Independent experiments show that hydrogen produced by rock crushing can support methane producing microbial communities over time.

Together, these findings point to fractured rock as a real source of hydrogen and organic molecules for deep ecosystems.

The Yellowstone team also found that fractured rhyolite released a detectable amount of dissolved organic carbon into the water.

That extra carbon could act as usable food for heterotrophic microbes, organisms that prefer consuming organic matter rather than relying on inorganic fuel.

Quakes influence Yellowstone ecosystems

Microbes living deep underground play a quiet but important role in how carbon, sulfur, and hydrogen move through the subsurface. 

Their activity shapes the chemistry of aquifers and can influence how gases and minerals cycle through volcanic regions.

Changes driven by seismic energy help reveal which organisms respond fastest when new chemical fuel appears. 

Those responses point to the kinds of metabolisms that remain active even in isolated environments where fresh resources are rare.

Signals on other worlds

Yellowstone is not the only place where rock and quakes interact. NASA’s InSight mission recorded more than 1,300 marsquakes before shutting down.

Those measurements showed that Mars is still seismically active. If subsurface ice or briny water moves through fractured Martian rocks, similar reactions could release hydrogen and other oxidants there. 

Microbes adapted to that chemistry would not need sunlight, only a steady supply of fresh fractures and flowing water.

On Earth, quake linked chemical pulses may help stabilize deep ecosystems over long periods by occasionally renewing their energy sources.

Even small, frequent earthquakes might shape underground biospheres beneath volcanic regions and slowly shifting crust. 

By watching Yellowstone’s microbes respond to a burst of shaking, the new work connects geology and biology. It suggests that each tremor in tectonically active regions can send an ecological signal through deep, unseen communities. 

The study is published in the journal PNAS Nexus.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–