The head of Iran’s Geological Agency says that in 300 plains in Iran the earth is sinking and huge sinkholes are appearing.

Alireza Shahidi says that the capital city Tehran is sinking 35 centimeters (more than a foot) a year, ISNA reports.

Shahidi compared Iran with the European Union and says that a four millimeter subsidence in Europe is considered a crisis, while the surface in many areas in Iran is subsiding 35 cm a year.

There have been frequent reports in the past three years in Iran about the ground sinking and sinkholes appearing. Last year, the official news agency IRNA reported that in some areas the ground has subsided 54 cm or nearly two feet, which is 140 times the world standard considered critical.

Shahidi also said that from 43 cases of hazardous conditions in the world, 34 are in Iran.

Mismanagement of underground natural water reservoirs is a major cause of earth subsidence. In Iran shortage of water has led to the depletion of underground reserves, which in turn cause the earth to sink and in some cases big sinkholes to appear.