Friction is overcome when the accumulating stress has enough force to cause a sudden slippage of the rock masses.
(Friction; is overcome; T:when the accumulating stress has enough force) (the accumulating stress; has; enough force to cause a sudden slippage of the rock masses)
Friction the accumulating stress
is overcome has
T:when the accumulating stress has enough force
enough force to cause a sudden slippage of the rock masses