Title

Spatio-temporal evolution of frequency-magnitude distribution and seismogenic index during initiation of induced seismicity at Guy-Greenbrier, Arkansas

Abstract

In this study, we carry out detailed analyses of the spatio-temporal variations of seismic b-value during the onset of the potentially induced-earthquake sequence between Guy and Greenbrier, Arkansas, to investigate correlations with pore-pressure change. The range of b-values suggests that the seismicity in the Guy-Greenbrier area is mostly a result of the activation of pre-existing faults. The spatial distribution of b-value correlates with modeled pore-pressure changes. In the northern segment of the fault, b-value increases with depth due to large pore-pressure changes and opening of new fractures in the deeper part and stress relaxation in the shallower parts. Whereas, in the southern segment, the shallower part shows higher b-values due to higher pore-pressure fluctuations but the deeper part in the crystalline basement has low b-value due to higher confining stress. The correlation between the temporal variation of b-value and hypocentral depth explains a previously observed temporal drop of b-value. This suggests that temporal variations should be interpreted along with the spatial variations. Estimation of the seismogenic indices for the Guy-Greenbrier fault is provided. Our analysis suggests that monitoring changes in b-value and seismogenic indices during an injection period might be used to avoid the occurrence of significant events if injection volume is reduced at critical times.

Publication Title

Physics of the Earth and Planetary Interiors

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