An Iranian newspaper has quoted a Tehran risk management official as saying that 6-in-10 of the city's buildings don't meet seismic standards and would be heavily damaged if a major earthquake hit.
The report in the Hamshahri newspaper quotes city risk management department head Reza Karami-Mohammadi as saying 1-in-5 of Tehran's buildings would be "completely destroyed" in a big earthquake.
Iran lies on the Iranian Plateau at the juncture of the Eurasian Plate to the north and the Indian Plate to the southeast and is one of the most seismically active countries in the world.
"Sixty percent of the buildings do not comply with the anti-seismic standards and will be seriously damaged" if a magnitude-6.5 or bigger quake were to strike, Karami-Mohammadi was quoted as saying.
He was reportedly speaking at a local council meeting to urge renovations to the Iranian capital's aging cityscape.
Tehran is home to around 9 million of Iran's 83 million or so people.
In 2017, a magnitude-7 earthquake near Iran's border with Iraq killed some 600 people and injured more than 9,000 others.
In 2003, a slightly smaller quake killed more than 26,000 people and leveled much of the historic city of Bam in southern Iran.