Supplemental Information Dataset

We develop a parallelized, partially-coupled, hydro-mechanical, discrete fracture network and matrix model (DFNM) model with thousands of fractures and the capability to calculate Mohr-Coulomb (MC) failure to indicate seismicity and alter hydraulic diffusivity. In consistent comparisons, DFNM-MC simulations allow for deeper, more heterogeneous pressure diffusion than EPM-TP simulations, and they do not need to employ unrealistic diffusivity values to result in pressure diffusion to seismogenic depths.

A sensitivity analysis shows that small deviations in fault orientation ( ≤2 degrees from optimal) and fracture network density outside an intermediate range can drastically decrease the likelihood of IIS, potentially explaining why only a small fraction of disposal wells are associated with IIS. The EPM-TP approach is unsuitable to investigate IIS, but the DFNM-MC approach offers a promising, nuanced approach for further study.