Efforts to monitor and characterize the recent increasing seismicity in central Oklahoma

Abstract

The sharp increase in seismicity over a broad region of central Oklahoma has raised concerns regarding the source of the activity and its potential hazard to local communities and energy-industry infrastructure. Efforts to monitor and characterize the earthquake sequences in central Oklahoma are reviewed. Since early 2010, numerous organizations have deployed temporary portable seismic stations in central Oklahoma to record the evolving seismicity. A multiple-event relocation method is applied to produce a catalog of central Oklahoma earthquakes from late 2009 into early 2015. Regional moment tensor (RMT) source parameters were determined for the largest and best-recorded earthquakes. Combining RMT results with relocated seismicity enabled determination of the length, depth, and style of faulting occurring on reactivated subsurface fault systems. It was found that the majority of earthquakes occur on near-vertical, optimally oriented (northeast-southwest and northwest-southeast) strike-slip faults in the shallow crystalline basement. In 2014, 17 earthquakes occurred with magnitudes of 4 or larger. It is suggested that these recently reactivated fault systems pose the greatest potential hazard to the region.

Source analysis of a potential hydraulic‐fracturing‐induced earthquake near Fox Creek, Alberta

“…Among the induced earthquakes observed worldwide, a moderate percentage shows a strike-slip focal mechanism [Zang et al, 2014]. Movements along buried faults, which are difficult to detect based on active-source seismic surveys, are likely responsible [McNamara et al, 2015;Zhang et al, 2013]. Our moment tensor inversions with full, deviatoric, and pure DC constraints suggest ∼80% DC and a strike-slip mechanism with vertical fault planes.…”

Relocated Hypocenters and Structural Analysis from Waveform Modeling of Aftershocks from the 2011 Prague, Oklahoma, Earthquake Sequence

“…Subsequently aftershocks followed within the same rupture zone, with one earthquake of M w 4.8 (8 November 2011, 02:46:57 UTC; U.S. Geological Survey [USGS]). The earthquake sequence had a swarm-like character, with large-and small-magnitude events interspersed in time (McNamara, Rubinstein, et al, 2015). The shaking of the main earthquake was felt widely into the neighboring states of Texas, Arkansas, Kansas, and Missouri.…”

Induced Microseismicity: Short Overview, State of the Art and Feedback on Source Rock Production

“…Over the last years, anthropogenic seismicity associated with shale plays production has been more and more reported [36], some events are directly associated with the fracturing fluid injection into the source rock as at Blackpool, in the UK [37], but major ones more often result from waste fluid re-injection in another formation. Since 2014, Alberta and British Columbia (Canada) and Oklahoma (US) [38,39] are "under monitoring" respectively, for a 4.4 magnitude event near Fox Creek, Alberta, in January 2015 and because of a significant increase in the number of earthquakes of magnitude greater than 3 in the whole state ( Fig. 7), [40].…”