Shake it up: More than 250 earthquakes hit Kansas in 2020
More than 250 earthquakes hit Kansas in 2020
There were more than 250 earthquakes in Kansas last year, with a flurry in central Kansas — and a strong quake in December near Wichita — that led to an investigation into the possible causes.
That investigation, by the Kansas Corporation Commission, looked at fracking — a practice by the oil industry used to bring crude to the surface. Ultimately, the KCC determined that did not cause the tremors felt throughout south-central Kansas.
“Based on our investigation, KCC staff does not believe the seismicity in Wichita, Kansas, is tied to any oil and gas activities in the area,” said Ryan A. Hoffman, director of the KCC Conservation Division.
The KCC investigation reviewed historical disposal well records for Arbuckle or Granite Wash injection wells within a 6-mile radius of the earthquakes. Five wells were located in the radius. No recent volume increases were found. The investigation also looked at any new drilling activity within 3 miles of the epicenters. No new wells were recently completed within the area. The KCC also performed spot checks of the wells within the radius area to verify compliance with permit conditions.
This investigation procedure is outlined in a 2014 Seismic Action Plan developed with the assistance of the Kansas Geological Survey and the Kansas Department of Health and Environment. An investigation is triggered whenever an earthquake of 3.5 magnitude or higher occurs in the state.
The Kansas Geological Survey monitors recorded 260 earthquakes in Kansas in 2020. Monitors have recorded three more since 2021 has begun.
According to the KGS, though they are not often felt, earthquakes are not rare. Every 24 hours, more than 1,000 earthquakes occur around the world. Eartquaketrack.com showed 64,873 quakes logged in the 365 days leading up to Jan. 8.
On the same day, the site showed 53 in the previous year for Newton, 50 in El Dorado and 26 in McPherson.
Earthquakes are created when rocks beneath the earth's surface suddenly move along faults, which are fractures that occur at weak points in the earth. The movement releases stress. The strength of the earthquake depends on the amount of stress released.
Of the earthquakes recorded in Kansas in 2020, the strongest was a magnitude 4.8 in Reno County on Jan. 19, 2020. There were 23 quakes recorded at three or higher — five of those recorded in Sedgwick County, including a 3.9 on Dec. 30, 2020, that was the second-highest reading of the year.
There are 15 seismometers in Kansas — 11 of those in the southern half of the state. The closest seismometer to Harvey County is in Sedgwick. For Butler County, there is also a seismometer in Sumner County. For McPherson County, the closest is in Saline County.
According to the KGS, some Kansas earthquakes are associated with the Nemaha Ridge, a buried mountain range that extends from roughly Omaha, Neb., to Oklahoma City. The ridge was formed about 300 million years ago and is bounded by faults that are still active today, especially the Humboldt fault zone that forms the eastern boundary of the Nemaha Ridge and passes near Wamego, east of Manhattan, and El Dorado, east of Wichita.