Fig. 4From: Preparation zones for large crustal earthquakes consequent on fault-valve actiona Schematics of fault-valve action after Sibson (2020); b shear stress, τ, and fluid-pressure, Pf, cycles contributing to dual-drive failure; c relative amplitudes of shear stress and frictional strength cycles resulting from valving action (b and c after Sibson 1992)Back to article page