Prague, Oklahoma, earthquakes: What we know

An earthquake "swarm" has no precise geological definition, but anyone who shook through many of the 40 quakes and aftershocks around Prague, Oklahoma, Friday night and Saturday morning surely felt stung.

By 3 p.m. Saturday, more than 24,000 people reported feeling the first big quake, according to the U.S. Geological Survey's online "Did You Feel it" feature, but people across this region of the United States took to social media to share their experiences. Millions could have felt it, authorities said.

Here's what we know about the main, 5.1-magnitude quake at 11:24 p.m. Friday and the ones that followed until 11:38 a.m. Saturday.

RELATED: Earthquakes rattled central Oklahoma Friday night. How bad were they?

What was damaged by the Feb. 2-3, 2024, earthquake episode in Oklahoma?

• People reported scattered dishes and household items, cracked drywall in houses and some tumbled exterior brick, but no injuries as of Saturday afternoon according to the Lincoln County Office of Emergency Management.

• Here's a map of earthquakes in Oklahoma over the past 30 days, from the Oklahoma Geological Survey. Friday's big quake and aftershocks came just a few weeks after a cluster of earthquakes were reported near Arcadia. The largest of those earthquakes was a 4.3 magnitude.

ARCADIA-EDMOND QUAKES: Oil and gas regulators investigating swarm of earthquakes near OKC; largest a 4.3 magnitude

Where exactly were these earthquakes in Oklahoma?

• People felt the big one across the state and into neighboring states, but they were all centered in one area 60 miles east of Oklahoma City.

• The first earthquake was at 11:24 p.m Friday, 5 miles northwest of Prague. The rest were in the same area between Prague and the tiny Sparks community 15 miles to the northwest.

If "Prague, Oklahoma," and "earthquake" sound familiar together, here's why

• The 5.1-magnitude quake Friday night was in the same area as the 5.7-magnitude quake in 2011 that led to a lawsuit against two state oil and natural gas companies over property damage, which was settled in 2017.

• Settlement of a second lawsuit from the 2011 Prague quake was announced just last fall.

• The lawsuits alleged that the 2011 quake was caused by oil and natural gas drilling companies' wastewater disposal wells.

Were the February 2024 Prague, Oklahoma, earthquakes tied to "fracking"?

• State seismologist Jake Walter said Saturday that this weekend's quakes also are probably related to disposal wells, which inject waste fluid into porous geologic formations underground. Walter noted that there was no indication that "fracking" caused the quakes.

• The Oklahoma Corporation Commission said Saturday that it was investigating.

• Drilling companies use hydraulic fracturing in production. Underground or ground water is mixed with additives to make fracturing fluids, which are then injected into targeted rock formations to free crude oil.

• However, wastewater disposal comes at the end of the fracturing progress, according to the Environmental Protection Agency.

Oklahoma Corporation Commission orders shutdown of disposal wells near Prague, Oklahoma

The Oklahoma Corporation Commission Oil and Gas Conservation Division ordered oil field wastewater disposal wells in the Arbuckle formation within 10 miles of Prague to begin shutting down operations, as its "initial response to mitigate the risk of further seismic activity," spokesman Matt Skinner said Saturday afternoon.

"The gradual shutdown process is necessary to avoid sudden pressure changes that could result in more seismic activity," Skinner said. "The Arbuckle formation is the state’s deepest formation.

"Oil and gas wastewater disposal into the Arbuckle formation has been linked to seismic activity in parts of the state.It should be stressed that that this action is an initial response. Further study may result in new directives."

Earthquake "swarm" or not, are the quakes and aftershocks over? Probably not, and here's why

• People in the Prague area can expect more quakes, Walter said Saturday in a statement from the Oklahoma Geological Survey.

• Expect several strong aftershocks in coming weeks that may be widely felt, Walter said.

• Most aftershocks are smaller than the main shock, but a small fraction of aftershocks can result in a larger earthquake than the main event, Walter said.

• The seismic hazard remains high in the area, he said.

• People should secure valuables that might shake during strong aftershocks and be ready Drop, Cover, and Hold On.

Here's where the top five most powerful of 40 earthquakes and aftershocks struck in Oklahoma Feb. 2-3, 2024.

According to the U.S. Geological Survey, here are the highest-magnitude quakes of this seismic episode:

• 5.1 magnitude, 11:24 p.m. Friday, 5 miles northwest of Prague.

• 3.5 magnitude, 12:33 a.m. Saturday, 5 miles west-northwest of Prague.

• 3.2 magnitude, 3:17 a.m. Saturday, 5 miles southeast of Sparks.

• 3.0 magnitude, 2:19 a.m Saturday, 5 miles northwest of Prague.

• 2.9 magnitude, 5:21 a.m. Saturday, 5 miles southeast of Sparks. Also, 2.9 magnitude, 4:48 a.m., 5 miles southeast of Sparks.

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Senior Business Writer Richard Mize has covered housing, construction, commercial real estate and related topics for the newspaper and Oklahoman.com since 1999. Contact him at rmize@oklahoman.com. Sign up for his weekly newsletter, Real Estate with Richard Mize. You can support Richard's work, and that of his colleagues, by purchasing a digital subscription to The Oklahoman. Right now, you can get 6 months of subscriber-only access for $1.

This article originally appeared on Oklahoman: Prague, Oklahoma, earthquakes: What we know