Fig. 4: Rupture speed versus driving load.
From: Laboratory earthquakes decipher control and stability of rupture speeds
a Normalized rupture speed \({V}_{{{{{{\rm{r}}}}}}}/{C}_{{{{{{\rm{S}}}}}}}\) of laboratory earthquakes as a function of the driving load \(\triangle {\tau }_{{{{{{\rm{d}}}}}}}^{2}/{\sigma }_{{{{{{\rm{N}}}}}}}\) with speed stability regions revised. The inset shows the definition of the local dynamic stress drop \(\triangle {\tau }_{{{{{{\rm{d}}}}}}}^{{{{{{\rm{local}}}}}}}\), with the gray strip delineating the transient weakening process. Rupture events on extremely smooth, smooth, and rough faults are represented by circles, squares, and triangles, respectively. The color of the symbol is coded by the horizontal stress \({\sigma }_{{{{{{\rm{X}}}}}}}\). Horizontal bar indicates the range of rupture velocity. Vertical bar indicates the range of driving load calculated from not perfectly uniform local dynamic stress drop \(\triangle {\tau }_{{{{{{\rm{d}}}}}}}^{{{{{{\rm{local}}}}}}}\). The dashed magenta lines represent model predictions based on the self-similar fracture analysis. b Normalized rupture speed \({V}_{{{{{{\rm{r}}}}}}}/{C}_{{{{{{\rm{S}}}}}}}\) of compiled natural strike-slip earthquakes as a function of the driving load represented by stress drop \(\triangle \tau\). Strike-slip events (squares) are chosen from the SRCMOD database43 (Supplementary Data 2) with the fast-rupture segments (diamonds) compiled from well-instrumented events (Supplementary Data 3). Error bars indicate the uncertainties from the references. Details in estimating the stress drop are given in the supplemental materials. Despite their scatter, the field data match well with the speed regions delineated by the theoretical model, that is in turn congruent with the laboratory data.
