This story first appeared on Cowboy State Daily
By Ellen Fike, Cowboy State Daily
Yellowstone National Park has seen almost 300 small earthquakes in the last week, according to the U.S. Geological Survey.
The event is a fairly typical earthquake swarm, the USGS said.
Earthquake swarms are sequences of elevated earthquake activity with no clear originating event and are common in Yellowstone and other places.
The park saw 280 earthquakes in just a few-day period, the USGS reported on Saturday on social media.
“Earthquake sequences like these are common and account for roughly 50% of the total seismicity in the Yellowstone region,” the USGS said on social media over the weekend. “This swarm is similar to one that occurred in about the same place during December 2020.”
Swarms occur in a variety of volcanic and tectonic settings and have several possible causes, ranging from a slow fault slip at a few patches between two tectonic plates or magma-filled cracks pushing their way through the crust.
The most common way swarms are generated, though, is when water enters and interacts with pre-existing fault lines in the earth’s crust, which is probably what caused the most recent swarm in Yellowstone, according to the USGS.
Yellowstone National Park’s seismic activity increased in 2020, with the park experiencing about 500 more earthquakes than in 2019. At least 1,722 earthquakes were recorded, an increase from 2019, when the park experienced 1,218 earthquakes.
The park can experience anywhere from 1,500 to 2,500 earthquakes per year, according to historical records.
Only three of the 1,722 earthquakes recorded in 2020 could actually be felt, meaning people reported some shaking.
Around 890 of the earthquakes occurred as a part of 26 swarms.The largest swarm occurred the week of Sept. 10, when 123 earthquakes happened in a one-week period.