Four terraced houses have been evacuated and a road closed in Norwich after "extensive" cracks caused serious damage to one of the houses.
Residents in Finkelgate, off Queens Road, were advised to leave their homes on Christmas Day after the cracks appeared the previous evening.
A depression and cracks also appeared in the road surface and pavements, Norfolk County Council said.
The area has been cordoned off over concerns about subsidence, it added.
An investigation is due to be carried out by highway and structural engineers.
Problems with door
Other residents in the area have been made aware of the problems, a council spokesman said.
The fire service were called on Christmas Eve to the house closest to the entrance to Notre Dame High School after the occupier discovered cracks and had problems closing a door.
Fire crews shored up the building to reduce the risk of further movement and collapse and the occupier was advised to find alternative accommodation, the county council said.
At lunchtime on Christmas Day, the fire and rescue service responded to a further call and found that the condition of the property had deteriorated, along with signs of subsidence in Finkelgate itself.
The immediate neighbours were advised to leave their homes and made their own accommodation arrangements.
National Grid carried out monitoring in case of leaks caused by possible damage to a gas main, the county council said.