Evidence for Transient Hydromechanical and Frictional Faulting Responses During the 2011 Mw 5.6 Prague, Oklahoma, USA Earthquake Sequence
Abstract
Mechanisms for the delayed triggering between the Mw 4.8 foreshock and Mw 5.6 main shock of the 2011 earthquake sequence near Prague, Oklahoma, USA were investigated using a coupled fluid flow and fault mechanics numerical model. Because the stress orientations, stress magnitudes, fault geometry, and earthquake source mechanisms at the Prague site have been well-characterized by previous studies, this particular earthquake sequence offered an opportunity to explore the range of physical processes and in-situ fault properties that could explain the 20 hour delayed triggering effect observed at the site. Our numerical experiments suggest that an initial undrained response resulting from elastic stress transfer from the foreshock followed by transient fluid flow along the fault may have contributed to the earthquake nucleation process. Base upon several plausible assumptions, the results of the numerical experiments were used to constrain fault compliance, fault transmissivity, and the characteristic slip-weakening distance for the fault that hosted the Mw 5.6 event. Fault zone compliance was estimated to be relatively large, tending towards values representative of a Skempton pore pressure coefficient near 1. Fault transmissivity was estimated to range from 10-15 to 10-13 m3 . Assuming that the fault was initially in the middle of its interseismic period, an upper bound on the slip-weakening distance was estimated to be appoximately 0.6 mm. This study has implications for understanding hydraulic properties, frictional properties, and faulting behavior of basement faults in Oklahoma that are large enough to host damaging earthquakes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.S53E..01N
- Keywords:
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- 4475 Scaling: spatial and temporal;
- NONLINEAR GEOPHYSICSDE: 7209 Earthquake dynamics;
- SEISMOLOGYDE: 7223 Earthquake interaction;
- forecasting;
- and prediction;
- SEISMOLOGYDE: 8164 Stresses: crust and lithosphere;
- TECTONOPHYSICS