'Hell hole' raging in China

A hole up to 80 m wide appears in the courtyard of a school in southern China.

The sight of a hole in a schoolyard in Hunan Province on China Central Television.Photo: CCTV.

The video broadcast by China Central Television shows the hole in front of a school building in Ningxiang County, Hunan Province. It is the playground of the students. Cracks also appear on buildings around the hole.

The land in the school began to sink from January, forming a hole of 20 m in diameter. Since then the hole has been constantly expanding as the land continues to sink.

Cracks appeared on the walls of houses around the hole.Photo: CCTV .

A local official told China Central Television that the phenomenon of subsidence occurred more strongly in the rainy season because of the heavy rain that caused the soil to become more dense. Families living in houses near the hole were evacuated and the local government supported each household with 300 yuan.

Dozens of large holes have appeared in China since April. In Sichuan province, 26 holes were discovered within a week, counting from April 27. The largest pit has a depth of 40 m and a diameter of 40 m. On June 4, a hole appeared in the middle of a highway in Zhejiang Province. It has a depth of about 6 m and a width of 8 m.

"Hellhole" is often formed in places that contain many easily soluble or soluble solids such as limestone, carbonate and salt. When groundwater flows through those hard substances, they will decompose or dissolve, leaving underground holes and caves. When the caves of the underground caves collapsed, it followed the land above that made the cave appear.