Loading of a porous rock with constant micro-seismic event rate suppresses seismicity and promotes subcritical failure

Catastrophic failure is the end result of a progression of damage towards brittle failure on a variety of system scales in the Earth. However, the factors controlling this evolution, and the relationship between deformation and the resulting earthquake hazard, are not well constrained. In particular, induced seismicity is a growing cause of concern in the engineering required for the net-zero carbon transition. Here we address the question of how to optimize operational controls to minimize microseismicity in a laboratory experiment where we can simultaneously image the underlying damage using x-rays and detect acoustic emissions. We show that using continuous servo-control based on acoustic emission event rate not only slows down deformation, but also suppresses events of all sizes, including extreme events. We develop a model that explains this observation, based on the the observed evolution of microstructural damage and the fracture mechanics of subcritical crack growth. The model is independently consistent with the observed stress history and acoustic emission statistics. Our results imply including seismic event rate control may be more effective in managing the risk from induced seismicity than current ‘traffic light’ systems based on extreme events alone.