High-velocity friction experiments on a fault gouge collected from the Nojima fault activated during the 1995 Kobe earthquake showed that the friction coefficient decreased from 0.63 to 0.18 over a slip weakening distance, D c , at high slip rates of ~ 1 m/s. The dramatic drop in friction coefficient of more than 0.3 is consistent with that for the Kobe earthquake estimated from seismological observations. Experimentally determined D c becomes 5 m at a higher normal stress of 1.85 MPa, close to the order of magnitude of seismologically determined D c of 0.5 to 1 m. The difference in D c is not significant because the fracture energy consumed during frictional slip is the same order of 106 N/m for both cases. Here we show that frictional behavior of a fault during an earthquake can be predicted by conducting high-velocity friction experiments.