Fig. 4: Evolution of differential travel times and waveform similarity throughout the seismic cycle.
From: Foreshock properties illuminate nucleation processes of slow and fast laboratory earthquakes
a–d Maximum cross-correlation coefficient and minimum DTT as a function of peak stress reached prior to co-seismic failure. Percent of peak stress is calculated by normalizing the instantaneous shear stress by the peak shear stress reached prior to co-seismic failure. We cross-correlate waveforms and estimate DTT using AE data from 15 seismic cycles (Fig. S1). Gray dots represent raw measurements and red line denotes the median derived from a moving window approach. DTT and waveform similarity remain constant throughout the seismic cycle for slow slip events at 8 MPa. Fast stick-slip events at 14 MPa show notable increase in DTT and decrease in similarity when the shear stress is below 40% of its peak stress. In contrast, the data show a significant uptick in waveform similarity and a decrease in DTT once the fault surpasses ~80% of the peak stress.
