Effect of initial damage on rock pulverization along faults

► High strain rate experiments are conducted on pre-damaged San Andreas Fault granite and intact Tarn granite. ► Both rocks pulverize at high strain rate, not low strain rate. ► The damaged granite switches from localized damage to diffuse damage (pulverization) at a lower strain rate threshold. ► Pulverization theory predicts such a behavior. ► This leads to a scenario of progressive pulverization of rocks along major fault zones.