Seismic swarms can stimulate microbial growth
By Damien Pin edited by Sarah Lewin Frasier
A swarm of 2,182 earthquakes in Yellowstone National Park was the key to a new discovery about microbes.
Cheryl Ramalho/Getty Images
With a little luck, specialized equipment, a supervolcano and a narrow hole 30 stories deep, researchers demonstrated that earthquakes don’t just shake rocks: they also boost populations of microbes living underground.
Up to 30 percent of life on Earth never sees sunlight; instead, these organisms obtain energy by consuming hydrogen generated by chemical interactions between water and rocks. Earthquakes fracture rocks, creating new reaction surfaces and changing the pathways water takes, increasing hydrogen production. For a study In Nexus PNASresearchers followed the effects of these upheavals on microbes at the bottom of a 100-meter-deep borehole in Yellowstone National Park.
The scientists made a 10-hour round trip to and from the test site seven times over seven months. There, they collected samples of rocks, dissolved gases and microbes, overcoming equipment malfunctions, logistical difficulties and more along the way. The group was fortunate to take measurements at the right time – and in the perfect place – to perfectly capture the rise and fall of a rare “swarm” of 2,182 earthquakes. Yellowstone experiences many earthquakes, but such powerful swarms tend to occur every five to 10 years, says Eric Boyd, a geomicrobiologist at Montana State University and lead author of the study.
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Over the course of the swarm, the amount of microbial life present increased 6.5 times before returning to normal after the shaking subsided. Hydrogen levels also increased and the types of microbes observed changed. “All the pieces fit together well,” Boyd says. “We put all this data together and we’re like holy cow!” »
Findings could offer clues to finding a fulfilling life beneath otherworldly surfacesAlso. “Extrapolation to other planets and moons suggests that subterranean life might be more easily found in seismically active locations,” says Steven D’Hondt, who studies life beneath the seafloor at the University of Rhode Island and was not involved in the work. “It’s a wonderful study,” he adds.
Caroline Freissinet, an astrobiologist at the French research institute LATMOS who was not involved in the work, says that while this is an excellent result for understanding Earth, the study is unlikely to make much difference to the search for life on our closest neighbor planet, Mars, due to its “hellish subterranean conditions.”
“In the past, Mars was wetter,” she says, “but what will remain of this temporarily increased activity today, four billion years later? »
The Yellowstone study was “a really difficult but really meaningful project,” Boyd says. “No one had done this before.” He is currently working on developing an automated sampler triggered by earthquakes to significantly increase data collection.
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