A swarm of 91 earthquakes rattled the Yellowstone National Park region in just 24 hours on Thursday, according to the United States Geological Survey. Michael Poland, scientist-in-charge at the Yellowstone Volcano Observatory, told McClatchy News in an email the cluster of quakes “is on the large side in terms of number and magnitude, but nowhere near the largest.”

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https://phys.org/news/2020-09-earthquakes-swarm-yellowstone-hours-experts.html