Residents of nine properties in the Conwy Valley have been evacuated following a "large" landslip.
Natural Resources Wales said the landslip happened in the Crafnant area near Trefriw.
A spokesperson said there is concern that the area could pose an "immediate risk" to nearby properties and roads.
Sian Williams, from Natural Resources Wales, said: “We are working quickly with a number of partners to monitor the landslip and determine if there are any movements.
“In the meantime, North Wales Police, Conwy County Borough Council and NRW have advised the residents of nine properties to evacuate their homes as there is a concern that this area remains unstable with an immediate risk to properties and highways in the area.
“There are road and footpath closures in place, and we advise people to stay away from the area.”
Engineering experts will continue monitor the landslide over the weekend when further rain is expected from Storm Dennis.