Fig. 6
From: Laboratory tests to understand tephra sliding behaviour on roofs
Repose angle and angle at which tephra grains started to move on the surface of the deposit for dry and wet pumice, scoria and ash. * Initial movement of wet ash varied with deposit thickness. 10 cm: sliding at the base (between tephra and roof) at 28° on metal sheet and slumping of deposit at 30° on fibre cement and tile; 20 cm: slumping at 21°