The United States Geological Survey recorded a Magnitude 2.7 Earthquake at a depth of 5.0 km, roughly 1 km to the southeast of the Oknoname Reservoir in Okfuskee County, Oklahoma, slightly after 3.05 pm local time (slightly after 8.05 pm GMT) on Sunday 22 September 2013. This is not a large quake, and is unlikely to have caused any damage or casualties, but is was probably felt locally.
The approximate location of the 22 September 2013 Okfuskee County Earthquake. Google Maps.
Oklahoma is naturally prone to Earthquakes, particularly in the southwest of the state, near the Meers Fault Zone, but since 2009 has suffered a sharp increase in the number of small quakes in the central and northeast parts of the state. While most of these quakes have been quite small, a few have been large enough to potentially cause problems, and any unexplained increase in seismic activity is a cause for concern.
In a paper published in the journal Geology on 26 March 2013, a team of geologists led by Katie Keranen of the ConocoPhillips School of Geology and Geophysics at the University of Oklahoma linked one of the largest of these quakes, a Magnitude 5.7 event in November 2011 which caused damage locally and was felt across 17 states, to the practice of pumping liquids (usually brine) into injection wells, which is common in the hydrocarbons industry and used to displace oil or gas, which can then be extracted from nearby extraction wells (where this is done in bursts at pressure to intentionally break up rock it is called hydraulic fracturing, or fracking). Significantly they suggested that the practice could lead to quakes years or even decades after the actual injection.
Witness accounts of quakes can help geologists to understand these events and the rock structures that cause them. If you felt this quake (or if you were in the area but did not, which is also useful information) you can report it to the USGS here.
See also Magnitude 2.9 Earthquake in Payne County Oklahoma, Magnitude 3.1 Earthquake in west Okfuskee County, Oklahoma, Magnitude 2.5 Earthquake in Van Buren County, Arkansas, Magnitude 2.8 Earthquake in southern Kansas and Magnitude 3.8 Earthquake on the New Mexico/Colorado state boundary.
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