Brumadinho incident

Dear fiends and colleagues, Can anyone give some technical information about this recent incident? How it happened? how to avoid such disasters in the future? (ADDED by WATER RESEARCH: WIKIPEDIA LINK TO BACKGROUND ABOUT THE INCIDENT AND LINKS TO ARTICLES ABOUT IT AND OTHER DAM DISASTERS ON THE WATER NETWORK: Brazil Dam Disaster death toll surpasses 110 Brazil's Minas Gerais Dam break