Evidence suggests Vale dam burst caused by liquefaction: Official

All evidence suggests that Brazilian miner Vale's deadly dam burst was caused by liquefaction, the same issue that led to the 2015 collapse of the Samarco dam which is co-owned by the company, a Minas Gerais state official told Reuters.

Liquefaction is a process whereby a solid material such as sand loses strength and stiffness and behaves more like a liquid. It is a common cause for the collapse of dams holding mining waste, known as tailings because the walls of these dams are mostly built with dried tailings which consist of a mixture of sand and clay-like mud.