As reported by Lao Dong Newspaper, from the end of March 2025 to present, in Kim Lu commune (Na Ri, Bac Kan), 7 sinkholes have appeared, directly threatening the lives and property of people in the area.
Of which, the largest hole has a diameter of nearly 5m, about 10m deep and the holes are being cordoned off, with warning signs to limit the danger to people.
According to the preliminary assessment of the Institute of Geological Sciences and Mineral Resources, the subsidence phenomenon in Bac Kan occurs in the area of sand distribution of allocated additives mixed with limestone or dolomite, a type of rock of carbonate origin, which is easily dissolved in natural conditions.
Above the holes are thick layers of thick material including sand, mixed sand, and lightning, with poor durability, loose state, and 3 - 5m thick.
Below are gray limestone layers, which have beenstered and cracked, developing many Karst caves containing water.
According to the geological mechanism, rainwater absorbs into the soil combined with CO2 in the air to form weak acid, thereby dissolving limestone over time.
Initially, it was just small cracks, but gradually large holes were formed in the ground.
When the pressure of groundwater decreases, especially due to excessive underground water exploitation, the ceilings of caves are prone to collapse, causing subsidence of the ground.
In addition to geological factors, the Institute also warns that at locations such as traffic routes where heavy trucks often pass by or large-scale construction works, the risk of subsidence increases due to mechanical impact.
In this situation, the Institute of Geological Sciences and Mineral Resources recommends zoning areas, erecting fences, warning signs at collapsed points and areas with unusual signs such as cracks in the ground, subsidence of house foundations.
Regarding technical solutions, it will be proposed to fill the hollow compartments with soil, stone, cement or concrete, and reinforce the surface with sustainable structures such as reinforced concrete and piles.
In addition, it is recommended that people temporarily suspend or reduce groundwater exploitation activities near residential areas.
The results of the study will be an important scientific basis to help determine the cause, propose sustainable solutions and support local natural disaster risk prevention planning, the Institute of Geological Sciences and Minerals emphasized.
At around 9:30 p.m. on May 26, at the subsidence point on National Highway 3B through Hiep Luc village, Kim Lu commune (Na Ri, Bac Kan), a motorbike driver fell down the barrier and fell into a deep hole.
As soon as the news was received, the authorities were present at the scene and organized a search, but so far the victim's whereabouts have not been found.
