Destructive mudflows as a consequence of tailings dyke failures

Disastrous mudflows, involving the movement of large volumes of semi-liquid tailings, have followed the failure of many tailings containments, For instance, the mudflow that followed the failure of a tailings dam complex at Stava, Italy, killed nearly 300 people, However, in other cases tailings dams have failed with very little post-failure movement or escape of tailings, This paper examines the behaviour and consequences of failures in five tailings ring-dykes in southern Africa and attempts to define the circumstances under which a mudflow will occur, It is shown that the occurrence of a mudflow is closely associated with the condition (dry or wet) of the ground surface on to which the escaping tailings move, If the ground surface is dry, it is likely that the tailings will not move far whereas if it is wet, a mudflow is much more likely to ensue.