Earthquakes often result in damage to buildings and infrastructure and sometimes loss of human lives. Induced earthquakes due to human activities like gas extraction, are the result of fast slip on powder-filled pre-existing faults in the subsurface due to a rapid breakdown of their strength. The physical mechanisms contributing to the rapid failure remain unclear. In this project we will perform experiments at scales of a single rock grain to millions of grains combined with computer models to investigate these weakening mechanisms. Our results will help to better constrain the hazard of induced earthquakes.