2011 Oklahoma earthquake

Geology

The Oklahoma Geological Survey believes the earthquake occurred along the Wilzetta Fault, which is also known as the Seminole Uplift. 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 and 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 in 2011 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.

According to the 2016 USGS report, "Earthquake rates have recently increased markedly in multiple areas of the Central and Eastern United States (CEUS), especially since 2010, and scientific studies have linked the majority of this increased activity to wastewater injection in deep disposal wells." In March 2013, an article published in the scientific journal Geology observed that "the volume of fluid injected into the subsurface related to the production of unconventional resources continues to rise" and this potentially triggered the earthquake. 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.

Damage

Early reports indicated that U.S. Route 62 had "buckled" in three locations and that several nearby homes had major damage and there were also numerous reports of broken windows and other minor damage, mostly to residences. Some local residents reported minor masonry damage and a chimney collapsed at one residence, while a few residents near the epicenter reported a noise which sounded like thunder in the distance as the earthquake struck. The Oklahoma Department of Emergency Management reported that two people suffered minor injuries, 14 homes had various levels of damage, and that Benedictine Hall at St. Gregory's University in Shawnee had one turret collapse and two others damaged, forcing the closure of the building. Sandra and Gary Ladra of Prague, suffered physical injuries and damage to their home, during the earthquake. They sued Spess Oil and Old Dominion, LLC, for compensation. In July 2017, Spess came to a confidential settlement in the case, which was before the Oklahoma Supreme Court.

Radar imagery

The National Weather Service (NWS) reported that weather radar detected insects, bats and birds which had apparently taken flight immediately after the quake. The NWS radar indicated that the tremors were significant enough that those animals that could leave the ground, did so.

References

References

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2. (September 7, 2016). "Magnitudes for Oklahoma Earthquakes Shift Upward". United States Geological Survey.
3. "Historic Earthquakes". United States Geological Survey.
4. (November 6, 2011). "Oklahoma Hit With 10 Aftershocks Following 5.6-Magnitude Earthquake". Fox News).
5. "Magnitude 4.7 – Oklahoma". United States Geological Survey.
6. "Preliminary Earthquake Report, November 5, 2011". Leonard Geophysical Observatory.
7. Achenbach, Joel. (March 28, 2016). "7 million Americans at risk of man-made earthquakes, USGS says". The Washington Post.
8. (March 28, 2016). "Induced Earthquakes Raise Chances of Damaging Shaking in 2016". United States Geological Survey.
9. (April 1, 2016). "Open-File Report".
10. Parker Gay, S.. (2003). "The Nemaha Trend—A System of Compressional Thrust-Fold, Strike-Slip Structural Features in Kansas and Oklahoma, Part 1". Shale Shaker.
11. "Earthquake Summary". United States Geological Survey.
12. Holland, Austin. (August 2011). "Examination of Possibly Induced Seismicity from Hydraulic Fracturing in the Eola Field, Garvin County, Oklahoma". Oklahoma Geological Survey.
13. (November 7, 2011). "Oklahoma Earthquakes Stronger Than Fracking Tremors, Experts Say". The Huffington Post.
14. Ellsworth, W.L.. (2013). "Injection-induced earthquakes". Science.
15. (2014). "Sharp increase in central Oklahoma seismicity since 2008 induced by massive wastewater injection". Science.
16. (2015). "Oklahoma's recent earthquakes and saltwater disposal". Science Advances.
17. (2015). "High-rate injection is associated with the increase in U.S. mid-continent seismicity". Science.
18. (2013). "Potentially induced earthquakes in Oklahoma, USA: Links between wastewater injection and the 2011 M_w 5.7 earthquake sequence". [[Geology (journal).
19. (March 7, 2014). "Observations of static Coulomb stress triggering of the November 2011 ''M''5.7 Oklahoma earthquake sequence". [[Journal of Geophysical Research]].
20. (November 5, 2011). "Oklahoma quake buckles highway, damages several homes". Los Angeles Times.
21. Dinger, Matt. "Record 5.6 magnitude earthquake shakes Oklahoma". News OK.
22. (November 6, 2011). "Quake update: Several homes, university damaged; assessment ongoing". Tulsa World.
23. [http://www.stwnewspress.com/news/local_news/oil-company-settles-earthquake-damage-suit/article_8281c799-98e9-545b-8519-293a01718aab.html Oil company settles earthquake damage suit], Michelle Charles, Stillwater ''[[News Press]]'', July 6, 2017. Retrieved July 8, 2017.
24. Israel, Brett. (November 7, 2011). "Oklahoma Quake Stirs Bird, Bug or Bat Swarm Seen on Radars". Our Amazing Planet.