Dr. Abdolazim-Amir Shah-Karami outlined the problem in an interview with the Iranian Students News Agency (ISNA). He is an advisor to the Office of Conservation, Revitalization and Registration of Historical Buildings of the Iranian Cultural Heritage and Tourism Organization (ICHTO).
He explained: “The atmospheric effects and stone decay of the outer-wall situated on the left side of the main stairway leading to the Persepolis Platform has caused three cracks to appear. For this reason, strengthening the wall and restoring it is a matter of utmost urgency, since a small tremor will cause the outer wall to collapse.”
Shah-Karami said that from an engineering standpoint, as opposed to artistic or archaeological standpoints, “the surrounding walls of Persepolis are the most important constructions of all. The outer walls not only carry their own heavy weight as well as the construction on the top, they also act as the platform stopper to keep it from moving and subsequently collapsing—in short, like a belt fastening the platform together.”
He said the main dangers to the outer walls are from an earthquake, since the city sits on two fault-lines, as well as sinking ground and rising moisture.
Achaemenid architects designed and constructed Per-sepolis 25 centuries ago in a way to withstand earthquakes and to deal with dampness, he said, calling the site a marvel of engineering.
“Persepolis was constructed in such a way that it could withstand any earthquake. The platform is connected in such a harmonious way, using limestone and sometimes sandstone. All the stones were fastened together with metal clips without using any mortar in between, which was an innovation. And in order to reduce the weight on the platform, many of the internal walls were constructed of mud brick clad in stones,” Shah-Karami said.
He said, “The system constructed in ancient times to rid the platform of moisture is still operating on the right section of the platform, but the left section [where the cracks have appeared] has been disabled.”
He said: “First and foremost, we have to clear the blocked air-vents that draw the moisture out of the platform. The soil behind the walls must be replaced. Most importantly, the wall must be reinforced to prevent its collapse and the cracked stones replaced.”