The State of Stress in Oklahoma: Insights from Dynamic Triggering

Abstract:

Induced seismicity, earthquakes caused by anthropogenic activity, has increased significantly in Oklahoma resulting from over a decade of wastewater injection. Oklahoma has been subjected to a few large earthquakes including the 2011 Mw 5.7 Prague event. The state of stress on faults within the crust is a fundamental property to understand the initiation of natural and anthropogenic earthquakes, however it cannot be measured directly. In order to understand the mechanisms leading to earthquake failure, we examine seismicity leading up to large earthquakes in Oklahoma and search for earthquake-triggering incited by natural transient stresses generated by the seismic waves of large remote earthquakes. We analyze ~7 years of data (2010-2016) from the Oklahoma Seismic Network, EarthScope's USArray Transportable Array (TA), and temporary local networks. We investigate 957 teleseismic earthquakes with M ≥ 6 and flag events that significantly increase seismicity throughout Oklahoma following the arrival of the teleseismic wave arrivals. We observe patterns of triggered seismicity indicative of evolving stress-state leading up to several large earthquake failures.