What term describes the sudden explosion of coal and/or rock from pillars or faces?

The term that describes the sudden explosion of coal and/or rock from pillars or faces is "outburst." This phenomenon occurs when there is an abrupt release of gas or pressure from the coal seam, leading to a violent ejection of material. Outbursts are particularly associated with the presence of high gas levels in the coal and can happen without warning, posing significant hazards to miners.

Considering other terms, while "explosion" may seem related, it is more general and does not specifically denote the context of coal mining or the rapid release of material in this specific manner. "Collapse" typically refers to the structural failure of tunnels or walls without the explosive nature described in the question. "Bump," often used in mining terminology, indicates a sudden rock movement or minor shift, but it does not encapsulate the explosive ejection aspect that "outburst" conveys. Thus, "outburst" is the most accurate term for sudden explosive events in mining contexts.