From Wikipedia, the free encyclopediaThe 2011 Oklahoma earthquake was a 5.6 magnitude intraplate earthquake which occurred on November 5, 2011, at 10:53 pm CDT (03:53 UTC, November 6, 2011) in the U.S. state of Oklahoma.According to the U.S. Geological Survey (USGS), it was the most powerful earthquake ever recorded in Oklahoma. The previous record was a 5.5 magnitude earthquake that struck near the town of El Reno in 1952. The quake’s epicenter was approximately 44 miles (71 km) east-northeast of Oklahoma City, near the town of Sparks and was felt in the neighboring states of Texas, Arkansas, Kansas and Missouri and even as far away as Tennessee and Wisconsin. The quake followed several minor quakes earlier in the day, including a 4.7 magnitude foreshock. The quake had a maximum perceived intensity of VIII on the Mercalli intensity scale as detected in the town of Prague. Numerous aftershocks were detected after the main quake, with a few registering at 4.0 magnitude.
Geology of the Earthquake
The Oklahoma Geological Survey believes the quake occurred along the Wilzetta Fault, which is also known as the Seminole Uplift. The Wilzetta Fault is a 55-mile (89 km) long fault zone that runs from central Pottawatomie County to the western part of Creek County. It is a strike-slip fault, where two adjacent crustal blocks slide horizontally past each other, but unlike the similar moving San Andreas Fault, the Wilzetta Fault is not located near the margins of any tectonic plates.