Healing Hagia Sophia

Historical landmark being restored to combat quake threats

For nearly 1,500 years, the Hagia Sophia has stood tall over Istanbul, weathering empires, earthquakes and time itself. But as the threat of another major quake looms, vulnerabilities in its aging structure have surfaced, and efforts are afoot to protect the iconic landmark.

“Hagia Sophia can be seen like a patient, with more health problems appearing as time goes on,” architect Hasan Firat Diker told Anadolu.

Now, working with the diligence of a doctor, Diker is part of the Hagia Sophia Scientific Committee, a team undertaking the building’s most extensive rehabilitation in a century.

The Hagia Sophia was built in the sixth century, and its dome – among the first built on pendentives – collapsed in 558, and partially again in 989 and 1346.

Since then, the structure and dome have held firm, even as other buildings around it fell in the quakes of 1509, 1526, 1766 and 1894.

“Hagia Sophia is the heart of Istanbul,” said Diker, a professor of architecture at the Fatih Sultan Mehmet Vakif University in the Turkish megacity.

“Its continued preservation can be attributed to the efforts of every ruling power – from the Byzantines to the Ottomans and into the Turkish Republic era – each doing their best within their economic means to protect it.”

‘Protect it, not alienate it’

The Hagia Sophia, a cathedral, museum and mosque at different points in time, is now undergoing its most extensive restoration since the founding of the Turkish Republic in 1923.

Initial work focused on surrounding Ottoman-era structures, but attention has now turned to the main building.

“We know its most vulnerable points. Our reinforcement efforts will proceed accordingly,” said Diker.

One of the biggest issues lies in the four asymmetrical arches supporting the main dome – a result of earlier repairs and historic damage.

“Especially after the last two major collapses during the Byzantine era, the dome and arches had to be rebuilt. But they were made thinner than they should have been, which made the structure more fragile and in constant need of protection,” he explained.

One major threat during earthquakes is hammering – a phenomenon where two adjacent buildings or structural components collide with each other due to insufficient separation between them.

“During an earthquake, the two semi-domes, which were built to support the main dome, can start to sway. This movement may create hammering, which risks damaging the main dome instead of protecting it,” he said.