Raise injection pressure until it exceeds a fracture's critical stress — it snaps open (cubic-law permeability jump) and a microseismic event fires. Watch heat output fall as cold water breaks through to the production well.
Pore-pressure diffusion opens a fracture network between injector and producer; cubic-law aperture growth vs. Mohr-Coulomb-style stress threshold drives induced seismicity and thermal drawdown.