Pressure diffusion controls maximum induced earthquake magnitudes

It is an open question if maximum induced earthquake magnitudes can be determined based on knowledge about operational parameters, subsurface conditions and physical process understanding. We analyzed a global compilation of earthquakes induced by hydraulic fracturing, geothermal reservoir stimulation, water disposal, gas storage and reservoir impoundment. Our analysis showed that maximum magnitudes scale with the characteristic length of pressure diffusion in the brittle Earth’s crust. An observed increase of the nucleation potential of larger magnitude earthquakes with time is likely governed by diffusion-controlled growth of pressure perturbed fault sizes. Numerical and analytical fault size modelling confirmed the findings. Finally, we derived scaling laws for the maximum possible and maximum expected magnitude for induced seismic hazard and risk forecasting and management.