The reactivation of faults and fractures in the Earth’s crust serves as a preferred pathway for fluid migration. Understanding the relationship between fault slip and fluid flow is essential for explaining both the triggering of earthquakes and the cycling of fluids and elements in the crust, driven by natural processes and human activities such as energy extraction and waste disposal. In this study, we conduct laboratory experiments to investigate how permeability changes in response to increasing fluid pressure, which can trigger fault slip and generate acoustic emission (AE) events. Analysis of calibrated AE data indicates that permeability changes occur through a cascade of small-scale events. While each event is much smaller than the fault itself, their cumulative area reaches 10 to 50 times larger than the fault area associated with a single permeability step. These cascading events may connect to form continuous fluid pathways, helping to explain why the cumulative energy from AE events correlates with the evolution of permeability. Therefore, AE monitoring may offer a way to estimate permeability changes, potentially allowing observed seismicity to constrain subsurface fluid flow behavior.