More Quakes Strike Oklahoma

Earthquake Hazard
.

Significant Quakes Continue to Strike Oklahoma

At least 10 shallow quakes measuring up to 4.1Mw have occurred in Oklahoma February 5 – 11, 2014.

The quakes have occurred at shallow depths of 3.6 – 5.2km. At least 27 earthquakes have occurred in the state of Oklahoma over the past 30 days.

Earthquake location map. Source: USGS/EHP.

Details of the Most Significant Quake in 30 Days

• Magnitude: 4.1Mw
• Event Time: 2014-02-09 02:16:01 UTC
• Location;: 35.876°N, 97.261°W depth=4.8km (3.0mi)
• Nearby Cities:
  • 7km (4mi) S of Langston, Oklahoma
  • 50km (31mi) NNE of Oklahoma City

Tectonic Summary

Earthquakes in the Stable Continental Region – Natural Occurring Earthquake Activity
[Excerpts from USGS/EHP]

Most of North America east of the Rocky Mountains has infrequent earthquakes. Here and there earthquakes are more numerous, for example in the New Madrid seismic zone centered on southeastern Missouri, in the Charlevoix-Kamouraska seismic zone of eastern Quebec, in New England, in the New York – Philadelphia – Wilmington urban corridor, and elsewhere. However, most of the enormous region from the Rockies to the Atlantic can go years without an earthquake large enough to be felt, and several U.S. states have never reported a damaging earthquake.

Induced Seismicity

As is the case elsewhere in the world, there is evidence that some central and eastern North America earthquakes have been triggered or caused by human activities that have altered the stress conditions in earth’s crust sufficiently to induce faulting. Activities that have induced felt earthquakes in some geologic environments have included impoundment of water behind dams, injection of fluid into the earth’s crust, extraction of fluid or gas, and removal of rock in mining or quarrying operations. In much of eastern and central North America, the number of earthquakes suspected of having been induced is much smaller than the number of natural earthquakes, but in some regions, such as the south-central states of the U.S., a significant majority of recent earthquakes are thought by many seismologists to have been human-induced. Even within areas with many human-induced earthquakes, however, the activity that seems to induce seismicity at one location may be taking place at many other locations without inducing felt earthquakes. In addition, regions with frequent induced earthquakes may also be subject to damaging earthquakes that would have occurred independently of human activity. Making a strong scientific case for a causative link between a particular human activity and a particular sequence of earthquakes typically involves special studies devoted specifically to the question. Such investigations usually address the process by which the suspected triggering activity might have significantly altered stresses in the bedrock at the earthquake source, and they commonly address the ways in which the characteristics of the suspected human-triggered earthquakes differ from the characteristics of natural earthquakes in the region.

Related Links

• M4.5 Quake Strikes NE Edmond Oil and Gas Field, Oklahoma December 8, 2013
• 41 Earthquakes Strike Oklahoma in November  December 1, 2013
• Earthquake No. 19 Strikes N. Texas November 29, 2013
• Two More Quakes Strike North Texas November 29, 2013
• Oil Drilling Likely Caused Texas Earthquake Posted on May 17, 2009
• M3.3 Quake Strikes Azle, Texas Posted on November 25, 2013
• FEWW Earthquake Links