Fig. 4. Comparison of our estimate of magnitude of maximum arrested rupture, ${\mathit{M}}_{\mathrm{w}}^{\text{max}-\text{arr}}$, for three values of γ with magnitudes of injection-induced earthquakes over a broad range of injected volumes.

We find that our estimate is equivalent to that of magnitude of maximum possible earthquake by van der Elst et al. (12) for b = 1; therefore, we also indicate the corresponding values of seismogenic index A_p. For completeness, we also include the estimate of maximum possible induced earthquake by McGarr (9). Note that for the events induced during multistage hydrofracking in the Western Canada sedimentary basin (yellow circles), we consider the total volumes for all previous stages and all proximal well completions reported as “maximum volume” by Atkinson et al. (11).