The United States Geological Survey recorded a Magnitude 4.0 Earthquake at a depth of 5.2 km in eastern Logan County, Oklahoma, slightly after 11.00 am local time (slightly after 4.00 pm GMT) on Monday 7 April 2014. There are no reports of any damage or casualties associated with this event, but it was felt across much of northern and central Oklahoma.
The approximate location of the 7 April 2014 Logan 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.
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