Mỹ Đức sinkhole formed naturally

The sinkhole suddenly appeared at around 8.30am last Saturday in the middle of Hòa Lạc village in An Tiến Commune, about 1.5 hours drive from Hà Nội’s centre. The hole was initially 4m across and 4.5m deep, but then quickly collapsed further to end up 11.3m deep and 13m wide.

Hà Nội’s Department of Natural Resources and Environment quickly carried out a geographic assessment before reaching their preliminary conclusion on Wednesday that the sinkhole was naturally occurring in a terrain called by geologists as karst.

The area around where the sinkhole collapsed was formed by limestone – a rock type below the surface that can gradually be dissolved by ground water. Spaces and caverns start to develop underground that can then trigger a sinkhole without warning.

This appears to be what happened in Hòa Lac village, where the sinkhole destroyed about 27m of a village road, blocking the access of 15 households to the main road. The out-of-nowhere sinkhole also literally sucked in some 30m² of resident Nguyễn Văn Bắc’s garden and his house’s gate, as well as taking the bathroom of Nguyễn Thị Sợi’s house.

An Tiến Commune People’s Committee Chairman, Trần Văn Hoành, said on Wednesday that the sinkhole caused damage of VNĐ125 million (US$5,500) excluding the residents’ losses.

The authorities supported Nguyễn Văn Bắc VNĐ2 million ($88) and VNĐ1 million ($44) to each of the other four households that suffered the most severe damage.

All five families were evacuated to a safer location.