Residents in Dong Phu Village discovered the cracks in Choi Mountain while collecting mushrooms in nearby forested areas and alerted local authorities after finding sections of ground that had subsided.
The crack extends for about 200 metres across the mountaintop. Several sections have subsided by 2 to 3 metres, with some reaching depths of 5 to 7 metres.
The affected area lies about 40 metres above Dong Trung Road, which connects National Highway 1A with the Ky Trung interchange on the North–South Expressway.
Tran Van Hai, head of Dong Phu Village, said the volume of soil and rock on the mountainside posed a significant risk if a landslide occurred, potentially blocking the road and endangering motorists.
Local authorities have installed warning signs, assigned personnel to monitor the site and advised residents to avoid the area during heavy rain or if further ground movement is observed.
They have also reported the incident to higher authorities for geological surveys and a long-term stabilisation plan.