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| date = November 6, 2011 | origintime = 03:53:10 UTC〔(【引用サイトリンク】url=http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usb0006klz/index.php )〕 | magnitude = 5.6〔 | depth = 〔 | location = | type = Strike-slip | countries affected = United States | damage = | intensity = VIII (''Severe'')〔 | PGA = | casualties = | related = Part of the 2009–15 Oklahoma earthquakes }} The 2011 Oklahoma earthquake was a 5.6 magnitude intraplate earthquake which occurred on November 5 at 10:53 p.m. CDT (03:53 UTC November 6) in the U.S. state of Oklahoma.〔 According to the United States 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.〔(【引用サイトリンク】url=http://earthquake.usgs.gov/earthquakes/states/events/1952_04_09.php )〕 The quake's epicenter was approximately 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.〔〔(【引用サイトリンク】url=http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usb0006k8b/ )〕〔(【引用サイトリンク】url=http://www.okgeosurvey1.gov/ )〕 The quake had a maximum perceived intensity of VIII (''Severe'') on the Mercalli intensity scale in the area closest to the epicenter.〔 Numerous aftershocks were detected after the main quake, with a few registering at 4.0 magnitude.〔 == Geology == The Oklahoma Geological Survey believes the earthquake occurred along the Wilzetta Fault, which is also known as the Seminole Uplift.〔 The Wilzetta Fault is a 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. From 1972 to 2008, between two to six earthquakes were recorded annually by the USGS, however 50 were recorded in 2009. The USGS and the Oklahoma Geological Survey are installing more seismometers to better monitor the increased activity. Aftershocks from the 5.6 quake, including some that can be felt, were expected to last for months. The Oklahoma Geological Survey reported that a minor earthquake swarm which occurred in January 2011 could possibly have been due to hydraulic fracturing, which is a process used to extract oil from oil wells. In November 2011 several geologists with the USGS that were contacted by ''The Huffington Post'' said that the 5.6 magnitude quake was not due to the mechanical process of hydraulic fracturing itself, which they said causes tremors on a much smaller scale. In March 2013, an article published in the scientific journal ''Geology'' concluded that the earthquake could have been triggered by the cumulative effects of injecting oil drilling wastewater under high pressure into the underground. An issue of the ''Journal of Geophysical Research'' published in March 2014 found that a magnitude 5.0 foreshock believed to be induced by fluid injection promoted failure of the rupture plain of the November 5 mainshock. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「2011 Oklahoma earthquake」の詳細全文を読む スポンサード リンク
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