At 7:02:44 am local time, a major, M5.6 earthquake hit 14km northwest of Pawnee, Oklahoma, and rattled a swath of the Great Plains, from Kansas City, Missouri, to central Oklahoma. It was the strongest quake to hit Oklahoma in years.
Immediate Facebook post reports indicated pictures fell off walls as far away as Tulsa. Others felt it in Norman and Wewoka in Seminole County. It lasted roughly 15 seconds. Saturday morning’s earthquake is the largest in Oklahoma since a 5.6 magnitude quake near Prague. That quake was followed by 10 aftershocks, according to the Associated Press:
The magnitude 5.6 earthquake and its aftershocks still had residents rattled Sunday. No injuries were reported, and aside from a buckled highway and the collapse of a tower on the St. Gregory’s University administration building, neither was any major damage. But the weekend earthquakes were among the strongest yet in a state that has seen a dramatic, unexplained increase in seismic activity.
According to press reports the quake was felt virtually across the entire midwest, from North Dakota through Houston - a 1,300 mile stretch:
Aftershocks lasted for several minutes according to the USGS.
Very substantial earthquake with aftershocks going on for several minutes. More information to follow.— USGS in Oklahoma (@USGS_Oklahoma) September 3, 2016
The quake was especially felt in Oklahoma City, while residents as far as Dallas said the shaking continued for at least 10 seconds. The earthquake was shallow, with a focus just 4.1 miles below the surface; such quakes convey more energy to the land surface; as the USGS notes the recent quake in Italy started at a 10km depth.
What is notable about the quake is that in recent months as a result of the decline in fracking, the number of quakes especially in the Dallas region, had declined significantly.
Since fracking activity went to near zero when oil price crashed very little in quake activity around DFW in 2016. pic.twitter.com/yr1tT6nmpU— Jeffrey Ray (@cbs11jeffrey) September 3, 2016
It’s not yet clear whether the earthquake caused any injuries or damage. Earthquakes hit Oklahoma frequently, but they are typically below 4.0 magnitude and rarely are felt in the northeast part of the state, according to Tulsa World.
USGS Ntl Equake Info Cntr has determined an preliminary magnitude of 5.6, 14 Km NW of Pawnee @ 7:02 am. Aftershocks may occur. #earthquake— USGS in Oklahoma (@USGS_Oklahoma) September 3, 2016
People in Kansas City, Missouri, Fayetteville, Arkansas, and Norman, Oklahoma, all reported feeling the earthquake at about 7:05 a.m. Saturday.
The shake map:
A seismograph of the quake when it hit, just after noon GMT.
According to the USGS the quake was particularly powerful due to its shallow nature:
The depth of the quake's focus was 6.6 Km or 4.1 miles, which is fairly shallow. #okquake— USGS in Oklahoma (@USGS_Oklahoma) September 3, 2016
Earthquakes w/shallow focus depths convey more energy to the land surface. For comparison, the recent quakes in Italy started @ 10 Km depth.— USGS in Oklahoma (@USGS_Oklahoma) September 3, 2016
The USGS has said on its twitter account that it hopes the M5.6 quake is not a foreshock of a similar or larger quake.
The Prague earthquake of 2011 was preceded by a strong 4.5 M quake. Hopefully this 5.6 was not a foreshock of a similar or larger quake.— USGS in Oklahoma (@USGS_Oklahoma) September 3, 2016
Owing to Oklahoma’s dramatic rise in earthquakes and a now-undisputed link between the seismic events and oil-and-gas disposal wells, the issue has gained political prominence that it didn’t have in 2011.