The Yellowstone Plateau volcanic field, spanning Wyoming, Idaho and Montana, is a hotspot of seismic activity. Between May and November 2021, more than 2,000 small earthquakes were detected with a maximum magnitude of just 3.6 M on the Richter scale.
While these events may not have destroyed the picturesque landscape, their effects underground are less obvious. Previous research has established that seismic activity changes the fluids passing through rocks underground. The research team, which included microbiologist Eric Boyd of Montana State University, set out to find out how underground energy is changing the microbes that call these water sources home.
The study, of which Boyd was the first author, was published in the journal PNAS Nexus. Boyd and his team collected fluid samples from a well that went nearly 300 feet deep off the shores of Yellowstone Lake. Over five sampling sessions throughout 2021, they examined how underground chemical and microbial communities had changed.
Read more: Fat molecules in deep-sea mud volcanoes reveal how microbes survive extreme conditions
Moving microbes respond to seismic shocks
The Earth's interior contains up to 30 percent of the Earth's biomass, often found in water flowing through bedrock. Subsurface microbial communities found in underground reservoirs are generally stable. But the germs are under Yellowstone Lake has changed over time.
After periods of seismic activity, chemicals such as hydrogen, sulfide and dissolved organic carbon increased; at the same time, Boyd and his team found higher concentrations of certain microbes in their samples. These include types Childrenbacteria And Desulfotomakulumwhich generate energy through the oxidation of inorganic molecules. When the earthquake swarms dissipated, these changes were reversed.
These shifts, the authors write, suggest that “the subsurface biosphere dynamically responds to geochemical changes caused by seismic events.” In other words, as seismic activity changes underground chemicals, microbes will respond to the resulting changes in available nutrients.
Grinding Stones Repeats Key Findings
The authors attempted to replicate their findings in the laboratory. To do this, they crushed samples of rhyolite, the main rock found in Yellowstone – in a jaw crusher and then ground into a fine powder. This process released organic carbon and hydrogen, suggesting that rock breakdown may have contributed to the chemical shifts they observed in the borehole samples. The authors suggest that the same process occurs on a massive scale during seismic activity in Yellowstone. The concentrations of hydrogen and dissolved organic carbon measured in the well were among the highest ever recorded on Earth. Yellowstone.
The authors say similar processes are likely to extend to other regions of underground seismic activity, both on Earth and on other planets. Seismic activity has been detected on Mars. The authors suggest that earthquakes could literally shake up the biomes of other planets, potentially making them more habitable.
Read more: Microbes in Yellowstone's thermal pools may shed light on ancient life
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