Understanding earthquakes caused by wastewater injection

Since 2009, many residents of the central US have been dealing with increasing earthquakes. Research has suggested that these vibrations are related to the injection of wastewater into deep wells by oil and gas companies. However, the precise dynamics of these earthquakes are still being revealed.

To shed new light, Pennington et al. examined the characteristics of a M_{with whom} 4.0 earthquake that shook Guthrie, Okla., in 2015. This earthquake was the largest in a series of earthquakes near Guthrie caused by sewage injection in the region.

The researchers used seismic data to computationally invert for the precise locations of slip along the debt during the earthquake. In addition, they compared the slip dynamics of the Guthrie quake with those of several other earthquakes of similar size that occurred along active or reactivated faults in North America and East Asia.

They discovered that the M_{with whom} The 4.0 Guthrie earthquake had a complex fault pattern with four different spots along the fault where slip occurred, similar to patterns seen for earthquakes along other reactivated faults. In contrast, earthquakes along active errors showed more diffuse slip patterns.

The findings suggest that the slip dynamics of the M_{with whom} 4.0 Guthrie earthquake was the result of non-uniform stress and force conditions that existed before the earthquake. Changes in pore pressure caused by wastewater injection likely improved these initial conditions. However, the structure of the fault probably gave rise to the characteristic slip pattern, where pore pressure played a secondary role.

These results could aid further research into the dynamics of reactivated faults, and they could aid in earthquake hazard modeling.

The research is published in the Journal of Geophysical Research: Solid Earth†

This story has been republished courtesy of Eos, hosted by the American Geophysical Union. Read the original story here†