coup de toit

OBS: [Le coup de toit peut] mettre en danger l'outillage et le personnel.

CONT: Rock bursts. In areas of very deep mining, as additional weight is supported by the pillars on the coal face, stresses may so build up that the yield point is reached. If the coal pillars, the roof, or the floor are able to yield gradually, the effects of the stresses are relieved by floor heaving, or by pillar or roof failure. Where the coal or the associated rocks are particularly strong and depths are much above average, these stresses may be relieved by rock bursts, which are relatively violent outbursts of the coal into the rooms and entries. Frequently, a large volume of gas (usually methane) is suddenly released during a rock burst in a coal mine.
OBS: for ""coal burst"" : Rock bursts and ""coal bursts"" in coal mines are generally designated by the term ""bumps"" or ""bounces"". A large proportion of these ""bumps"" or ""bounces"" are actually ""coal bursts"" due to fracturing of pillars and remnants and need not involve any fracturing of roof or floor rock.