Fig. 2: Spatiotemporal variations of shear stress and foreshock activity prior to the mainshock. | Nature Communications

Fig. 2: Spatiotemporal variations of shear stress and foreshock activity prior to the mainshock.

From: Two end-member earthquake preparations illuminated by foreshock activity on a meter-scale laboratory fault

Fig. 2

a Typical evolutions of local shear stress and foreshocks just before a mainshock in LH without PEG. The color indicates the normalized shear stress change; the displayed shear stress in each location has been normalized by the maximum value after subtracting the initial value in the corresponding time period. See Fig. 1c, d for the absolute values. Open star indicates the time and location of the precursory slow slip initiation. b Zoom-in view of (a) for the last 50 ms. c Evolution of foreshock number in LH without PEG. d Histogram of the slow slip initiation times in LH without PEG. e Typical evolutions of local shear stress and foreshocks in MH with PEG. The displayed shear stress has been normalized in the same way as (a). f Zoom-in view of (e) for the last 50 ms. g Evolution of foreshock number in MH with PEG. Seismic events that occurred at t* larger than 0.9 (gray bars in (c) and (g)) were considered as aftershocks and were excluded from the analysis.

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