Several incidents of land subsidence occurred in northern Quang Ninh province yesterday, resulting in the creation of five large holes that pose a risk to locals, forcing the evacuation of dozens of families to safe places, authorities reported.

The occurrence took place at 5 am on August 21 in the Thuy Son residential area in Cam Son Distrcit, Cam Pha City, when a local man, Luu Dinh Son, realized he couldn’t open the front door of his house, as the house’s floor had sunk, thus blocking the door.

After some neighbors helped Son force the door open, a small hole formed underground and it rapidly cracked and subsided, resulting in a larger, deeper one.

At noon, more subsidence continued to occur, creating four more holes, the largest and deepest of which was 15 meters wide and 7 meters deep.   Along with sunken land, numerous houses in the area had sustained cracked walls and foundation damage. Of the houses, four could collapse at any time, authorities warned.

Concerned agencies helped the affected household in removing people and property to safe places.

The Cam Son Ward People’s Committee mobilized forces to level the holes to protect locals and ensure traffic safety. Authorities also erected signs warning people not to enter dangerous areas.

Recently, Cam Pha City and Ha Long City have seen many deadly holes suddenly appear.

Vu Van Hien, chairman of the ward committee, said several groups of scientists from central and provincial levels have arrived in Cam Pha to study the situation.

Initial results of one geological survey revealed that there are many underground water reservoirs in Cam Son, Hien said.

On October 2, 2011, the third land subsidence within a month occurred in Quang Ninh, creating a huge hole that led to an urgent evacuation of tens of families. The accident occurred along with a terrible noise from underground in Cao Xanh Ward, Ha Long City, leaving a large hole, 5 m wide and 20 m deep, which put many houses nearby at risk of collapse. Soon afterwards, authorities urgently evacuated 14 families and continued to move many others to safe places.