On April 23, 2025, a 6.2 magnitude earthquake in the Sea of Marmara struck Türkiye's largest city, Istanbul, causing widespread panic and injuring over 230 people, primarily due to falls and panic-induced accidents. Over the course of the day, at least 272 aftershocks were recorded, with the strongest reaching a magnitude of 5.9. According to an initial statement by Minister of the Interior Ali Yerlikaya, there was no major destruction apart from the collapse of a single abandoned building. However, the event has reignited public and professional discourse around the city's preparedness for a much larger seismic event, long anticipated by experts monitoring the North Anatolian Fault.
As residents evacuated buildings and tried to gather, spend the day and night in public squares and parks, the role of open urban space became immediately apparent, not only as a safety measure but as an essential element of emergency response. These experiences, once again, underlined the spatial importance of safe evacuation routes, seismic performance of materials, and the presence, or absence, of well-designed public areas that can serve as temporary refuges during disasters.
Istanbul, home to over 16 million residents and a vast stock of buildings, both historical and contemporary, sits precariously close to one of the world's most active fault lines. Seismologists have consistently warned that a major earthquake is likely to strike the region within the coming decades. In response, various public institutions and urban planning bodies have introduced policy discussions aimed at reinforcing existing structures, updating building codes, and prioritizing high-risk zones for urban transformation. Yet, the scale of vulnerability and the complexity of retrofitting a city of such layered development continue to challenge these efforts.
The 1999 İzmit earthquake, caused by a rupture along the North Anatolian Fault, resulted in over 17,000 fatalities and prompted significant revisions to Türkiye's seismic building codes, aiming to enhance structural resilience. However, the devastating earthquakes in southern Türkiye in February 2023 revealed persistent enforcement issues. Despite updated regulations, many buildings collapsed due to non-compliance, with factors such as unauthorized construction and insufficient oversight contributing to the destruction.
These recent earthquakes reminded Istanbul of its expected quake once again, and the pace of structural assessments, mainly requested by residents, across Istanbul has increased, with authorities focusing on evaluating the earthquake resilience of existing buildings. According to findings from the Istanbul Province Probable Earthquake Loss Estimates Update Project, a scenario involving a 7.5 magnitude earthquake could result in moderate to severe damage to approximately 17% of the city's building stock, equating to nearly 194,000 structures.
To prepare Istanbul for such a large-scale disaster, efforts are ongoing in several key areas, including urban transformation projects, the reinforcement of structures with high damage risk, and the restoration of cultural heritage buildings. However, growing concerns remain, especially considering the anticipated proximity of the next major earthquake and the extended timeline required to make the entire city resilient. For architects, engineers, urban planners, and policy makers, the earthquake serves as a reminder of the urgent need to integrate seismic resilience into every stage of the design, construction, inspection, and after-construction process. In many parts of the world, earthquake risk is a reality, and the effectiveness of earthquake-related policies in these processes has been experienced firsthand through multiple events. The professions face a dual responsibility: ensuring that new structures meet high seismic standards, while also developing innovative, adaptive strategies for existing buildings, many of which cannot be easily demolished or replaced.
Although the April 23 earthquake caused no major destruction, it underscores a reality that Istanbul's residents, planners, and policymakers can no longer afford to overlook. As seismologists continue to warn of a possible larger event in the region's future, the need for comprehensive, coordinated, and design-conscious preparedness becomes more urgent.
