Istanbul, the ancient city straddling East and West, is built on one of the world’s most active fault lines, putting its 40,000 historical sites and thousands of residential buildings at risk. A major earthquake could imperil these structures, claiming up to 700,000 lives.
The North Anatolian Fault, which runs just 10 miles from Istanbul, has produced many major earthquakes since 1900, but a 70-mile stretch remains dormant, causing concern among experts. Geophysicists predict that in the next 30 years, Istanbul will experience a 40 to 60 percent chance of a major earthquake.
Efforts to protect the city’s landmarks have been hindered by a split between the city government and the central government, led by President Recep Tayyip Erdogan. The Ankara-led authority has taken some steps to reinforce at-risk buildings, but full fortification comes at a huge cost.
Historic sites like the Hagia Sophia, Basilica Cistern, and Zeyrek Cinili Hamam require seismic isolators or base isolators to withstand major earthquakes. However, installing these devices is difficult due to historic preservation rules and high costs.
The Ankara-led government has launched measures to protect these sites, such as upgrading the steel framework of Hagia Sophia and reinforcing the exterior to protect its ancient mosaics. The Istanbul Metropolitan Municipality aims to preserve this place forever, but it faces similar hurdles in taking action.
A private structure like Zeyrek Cinili Hamam was extensively reinforced with lime mortar, brick, and stone, which can withstand 2,000 years of seismic activity. However, acquiring and restoring such structures is costly, with prices ranging from tens to millions of euros.
As the clock ticks away, experts warn that Istanbul must take drastic action to mitigate earthquake risks. “The question is when, not if,” said Wendy Bohon, a geologist.
Source: https://www.washingtonpost.com/world/interactive/2025/istanbul-earthquake-hagia-sophia-basilica-cistern