Monday 16 September 2013

Magnitude 2.8 Earthquake in southern Kansas.

The United States Geological Survey recorded a Magnitude 2.8 Earthquake at a depth of 5.0 km in southern Kansas, close to the border with Oklahoma and about 100 km southwest of Wichita, slightly after 1.50 pm local time (slightly after 6.50 pm GMT) on Saturday 14 September 2013. An Earthquake this size is highly unlikely to have caused any damage or injuries, but was reportedly felt locally.

The approximate location of the 14 September 2013 Kansas Earthquake. Google Maps.

Earthquakes on southern Kansas are rare, and their causes poorly understood. There are two fault zones in the south of the state, The Humbolt Fault to the southeast of Wichita and the Crooked Creek Fault to the southwest of Dodge, though both of these are ancient structures not considered to be particularly active, and both lie a long way from this event. 

Small Earthquakes have also been attributed widely to the activities of hydrocarbons companies, notably the extraction of oil and gas, which is a major industry in Kansas, but not in the area affected by this quake. In particular the process of hydraulic fracturing, or fracking, in which water, sand and chemicals are forced into buried sediments at considerable pressure in order to shock them into releasing trapped hydrocarbons, is often linked to Earthquakes, but this is restricted to the east of Kansas. The practice of storing hydrocarbons in underground salt deposits that have previously been worked commercially has also been linked to seismic events, as it causes repeated inflation and deflation of the affected beds, which can trigger previously quiet and unnoticed faults. Again this occurs in Kansas, but is restricted to the central part of the State, and is unlikely to be connected to this event.

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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