The nonlinear shear strength, friction angle, and cohesion in planetary subsurfaces. (a) The depth-averaged shear strength (﹩\bar{\tau }﹩) variation with maximum depth (﹩{z}_{{\rm{\max }}}﹩). (b) The depth-averaged apparent friction angle (﹩\bar{{\varphi }_{\mathrm{app}}}﹩) variation with maximum depth. (c) The depth-averaged apparent cohesion (﹩\bar{{c}_{\mathrm{app}}}﹩) variation with maximum depth. The profiles were calculated using the surface gravity and density values in Table 2 and assuming nonlinear model parameters representative of cohesionless loose sand or gravel (φ_∞ = 35°, Δφ = 10°, σ_h = 10 kPa, and c = 0).