Pore pressure observations of tidal response in the Arbuckle indicate vertical fluid flow and have been interpreted to suggest the Arbuckle is not fully confined (Wang et al. At its peak in 2014, the annual volume of saltwater disposal into the Arbuckle reached more than 1.05 billion barrels (Murray 2015). Saltwater disposal primarily targets the Arbuckle Group, a highly permeable sedimentary unit that is directly upsection from the granitic basement (Ham 1973 Morgan & Murray 2015). 2015), with a smaller portion of earthquakes attributed to hydraulic fracturing (Holland 2011 Skoumal et al. 2014 Walsh & Zoback 2015 Weingarten et al. Much of the increase in earthquake rates in Oklahoma has been linked to deep disposal of saltwater resulting from oil or gas production (Keranen et al.
Earthquake rates in Oklahoma peaked in 2014–2015 and have since declined (Norbeck & Rubinstein 2018) as regulations and economics have reduced disposal volumes. More generally, an increase in the earthquake rates above background in Oklahoma and across the Central and Eastern United States was observed beginning in 2009 (Ellsworth 2013 Llenos & Michael 2013).
#How long is the fault in our stars full movie series#
The Prague sequence was the first in a series of moderate earthquakes that occurred in central to northern Oklahoma related to wastewater disposal, including the M 5.0 Cushing, M 5.1 Fairview and M 5.8 Pawnee earthquakes (e.g. The main shock was preceded ∼20 hr beforehand by a M 4.8 foreshock and the largest aftershock, a M 4.8, occurred ∼48 hr after the main shock. On 6 November 2011 at 3:53:10 UTC a M 5.7 earthquake occurred near the town of Prague, Oklahoma, and was subsequently linked to nearby wastewater disposal (Keranen et al. Induced seismicity, Rheology and friction of fault zones, Seismic anisotropy INTRODUCTION The results suggest elevated pore fluid pressures likely induced failure along several of the faults activated in the 2011 Prague sequence. Our results confirm that induced event sequences can occur on faults not optimally oriented for failure in the local stress field. Both the M 4.8 foreshock and M 4.8 aftershock occur on fault planes that deviate 20–29° from the optimal orientation for slip. We find that only two of the fault planes, including the M 5.7 main shock fault, are optimally oriented. We assess whether the five near-vertical fault planes are optimally oriented to fail in the determined stress field. From an extended catalogue, we map ten distinct fault segments activated during the sequence that exhibit a wide array of orientations.
We find that the dominant azimuth observed is parallel to previous estimates of the regional compressive stress with some secondary azimuths oriented subparallel to the strike of the major fault structures. We estimate the local principal compressive stress direction near the rupture as inferred from shear wave splitting measurements at spatial resolutions as small as 750 m. Here, we examine the 2011 M 5.7 Prague earthquake sequence that was induced by nearby wastewater disposal. The orientations of faults activated relative to the local principal stress directions can provide insights into the role of pore pressure changes in induced earthquake sequences.