Fig. 10
From: Physical characteristics of scoriae and ash from 2014–2015 eruption of Aso Volcano, Japan
a Stress and b friction coefficient of ash measured by steady shear deformation. a Shear stresses measured under one-directional rotation with a shear rate of \(0.01 \, \hbox {s}^{-1}\) at various normal stresses, temperatures, and grain sizes. b Friction coefficient as a function of the strain and shear rate