TEHRAN -- Zoroaster’s Kaba is in extreme danger of collapse due to escalating earth sinkage at the ancient site of Naqsh-e Rustam in Fars Province.

The measured earth sinkage previously reported by experts was five centimeters, but a new survey shows that this amount has increased over the past few days, the Persian service of the Mehr News Agency reported on Monday.
Experts believe that the occurrence may lead to the destruction of Zoroaster’s Kaba, which is located at a distance of five meters from the sinking earth.
The mishap could cause cracks in rocks bearing the ancient bas-reliefs, they surmised.
Drilling numerous wells and consequent reduction in the level of water tables in the region is the main factor causing the phenomenon, experts previously said.
“The earth sinkage may result in a landslide or a rift that could destroy the ancients sites located in the region,” geologist Hassan Musavi told Mehr.
“Unduly draining water from the numerous wells dug by the local farmers nearby is the main reason for this incident,” he added.
In order to prevent a cultural heritage catastrophe in the region, he said that further exploitation of the wells must be stopped until water table levels are restored.
Zoroaster’s Kaba is one of the most important sites in the Naqsh-e Rustam region. There are various theories on the original purpose of the monument. Some experts believe that the monument was the home of a complete copy of the Avesta which had been written on 12,000 leather parchments. Some orientalists also believe that Zoroaster’s Kaba was a place where the Zoroastrians’ sacred fire was perpetually kept burning.
Other researchers say that the monument is the tomb of Smerdis, the son of Cyrus the Great, who was murdered by his brother Cambyses, king of Persia in 529–522 BC.
Some archaeologists also believe that the site was used as an ancient government archive.
However, in 2005, Iranian archaeologist Reza Moradi Ghiasabadi rejected this theory and described the monument as the world’s most unique calendrical and astronomical building.
Zoroaster’s Kaba bears a Sassanid era inscription explaining the historical events during the reign of the Sassanid king Shapur I (241-272 CE).
The trilingual inscription, written in the Sassanid and Parthian dialects of Middle Persian and ancient Greek, describes the war between Persia and Rome in which Shapur I defeated Valerian, who was captured in 260 and died in captivity.
Naqsh-e Rustam is home to the tombs of the Achaemenid kings Darius I, Xerxes I, Artaxerxes I, and Darius II, and several other sites dating back to the Elamite and Sassanid eras.