The crack appeared after heavy rain from September 13 to 19 in Dong Luong Commune, running 15-50 metres from the foot of the hill, local authorities said.
The landslides also damaged about 400 metres of Road 530B.
In the Na Nieng area of Tan Lap Village, more than 20,000 cubic metres of earth and rock are estimated to have collapsed. Cracks measuring 70-100 metres long have appeared, with some areas subsiding by 60-70 cm and others sinking by around 1.5 metres.
The landslides have affected 34 households with 180 residents, as well as four classes at a local preschool. All 34 households have been evacuated to safer areas amid concerns over further landslides.
Provincial authorities declared a landslide emergency for the Na Nieng and Na Lo hills on September 29.
Local authorities have been instructed to monitor the affected areas, erect barriers and warning signs and prevent people from entering high-risk zones.
