Iran’s heritage sites threatened by accelerating land subsidence, experts warn

Centuries-old monuments across Iran are facing increasing risks from land subsidence driven by decades of groundwater over-extraction, according to scientists and cultural-heritage officials. Sites of global importance such as Persepolis, Naqsh-e Jahan Square, and the Tomb of Cyrus are now located within some of the country’s most subsidence-prone regions. 

Geologists cited by Tasnim News Agency reported that ground deformation has accelerated across the provinces of Isfahan, Fars, and Tehran, with field evidence including cracks, fissures, and foundation instability observed near ancient structures.

Geologist Ali Shahbaz noted that “nearly half of Iran’s valuable historic fabric lies in subsidence-prone zones,” estimating that 63 nationally registered monuments and 27 world-class sites are currently affected.

In Isfahan, the desiccation of the Zayandehrud River has been linked to ground settlement rates of 16–25 centimeters per year in the city’s northern areas. The deformation is raising stability concerns for Naqsh-e Jahan Square, the Shah Mosque, Sheikh Lotfollah Mosque, and the Safavid-era bridges Si-o-se-Pol and Khajou, all integral to the UNESCO-listed urban landscape.

In Fars Province, subsidence in the Marvdasht Plain, estimated at 14 centimeters annually, threatens drainage systems and stone foundations at Persepolis. Experts have also issued warnings regarding the Tomb of Cyrus at Pasargadae and the rock-cut necropolis of Naqsh-e Rostam, where gradual soil compression and differential settlement could undermine archaeological layers over time.

Nationwide, officials describe subsidence as a “silent crisis.” According to Iran’s Geological Survey, over 380 cities and 9,000 villages have recorded measurable ground sinking, with about 42 million residents living in affected zones. The agency attributes the trend to two decades of drought, unregulated groundwater pumping, and fragmented water governance, which have pushed 106 plains into irreversible subsidence conditions.

While cultural-heritage authorities emphasize that no major site faces imminent collapse, they caution that progressive deformation, combined with drying soils and sporadic heavy rainfall, could cause irreparable structural damage over the coming decades. “No site is on the brink today,” Shahbaz said, “but without curbing withdrawals and restoring groundwater, we are setting the stage for losses that cannot be repaired.”