30 CFR § 57.3200
Correction of Hazardous conditions.
Scaling and Support--Surface and Underground
Ground conditions that create a hazard to persons shall be taken down or
supported before other work or travel is permitted in the affected area.
Until corrective work is completed, the area shall be posted with a warning
against entry and, when left unattended, a barrier shall be installed to
impede unauthorized entry.
For further information: See MSHA's Program Policy Manual