‘ Earthquake hypocenters and focal mechanisms in central Oklahoma reveal a complex system of reactivated subsurface strike-slip faulting, McNamara et al. , Geophysical Research Letters, 2015. ‘

Since late 2009, there has been a notable increase in the number of earthquakes with magnitude greater than 3 in Oklahoma. Given that the most recent activity does not follow patterns normally observed in the area, many  believe that fluid injection of wastewater from the oil and gas industry may be contributing to the increased seismic activity.

To better understand the cause of this activity and to better assess potential hazard, McNamara et al. used a multiple event location method to relocate over 3,600 events and used Regional Moment Tensors to compute source parameters for 195 events in Oklahoma.

They found that a majority of faults are optimally oriented for failure relative to the regional compressive stress field and that most of the earthquakes originate in the shallow crystalline basement. Based upon these observations they believe that there is a high potential earthquake hazard in Oklahoma.

For more details check out the article here.