Slip‐weakening distance estimated at near‐fault stations

We estimated the slip‐weakening distance from the seismograms recorded at near‐fault stations, considering the effect of spatio‐temporal filtering for a continuous propagation of rupture. This effect is usually observed at some distance away from the fault. We used a Green's function for 2‐D anti‐plane rupture propagating with constant rupture velocity and instantaneous slip at the crack tip. As a source time function, we used a regularized Yoffe function which is a kinematically good approximation of dynamic slip‐weakening behavior. By convolving these functions, near‐fault waveforms are computed. As a proxy of slip‐weakening distance ( D c ), we used D c ′, which is defined as a slip at the time of peak slip velocity. Then, D c ′ values can be computed as a function of the distance from the fault. This procedure is applied to the observation of the 2000 western Tottori, Japan, earthquake ( M W 6.6) as well as the 2002 Denali, Alaska, earthquake ( M W 7.9). We estimated D c ′ at about 0.3 m at GSH station (∼100 m away from the fault) for the Tottori earthquake and that at about 2.5 m at PS10 station (∼3 km away from the fault) for the Denali earthquake. We confirmed that both estimates are not affected by the spatio‐temporal smoothing.