Fig. 1
From: Which is heterogeneous, stress or strength? An estimation from high-density seismic observations
Two different explanations of focal mechanisms. a A case of ordinary stress inversions (e.g., Gephart and Forsyth 1984; Michael 1984, 1987). Stress is assumed to be uniform in the analysis area. Small rectangles indicate faults. Green and red arrows indicate observed slip directions from focal mechanisms and calculated slip directions inferred from the direction of maximum shear on the fault, respectively. Brown arrows indicate axes of the maximum compressional stress. b Hypothesis of Smith and Heaton (2011). Each fault plane is subjected to different maximum compressional stress, as indicated by brown arrows. Earthquake slips occur only on the faults indicated by colored rectangles, on which the stress has a similar orientation to the incremental stress