Istanbul’s earthquake danger: What data reveals about future risks?

Türkiye has addressed growing concerns over a potential major earthquake in Istanbul, as seismic activity intensifies in the region.

According to the newspaper Türkiye, a state of emergency has been declared in Greece due to increased seismic movements in the Aegean Sea, while recent tremors have also raised concerns in Türkiye, per Caliber.Az.

Scientists are closely monitoring the potential for a significant earthquake in Istanbul.

Geologist Prof. Osman Bektaş has assessed the risk levels, stating that the eastern part of the city has a lower likelihood of a major earthquake. However, he highlighted the western segment as an area of concern.

Historical data indicates that the estimated magnitudes of the earthquakes that struck the Adalar fault region, east of Istanbul, in 1509 and 1766 ranged between 6.8 and 7.2. Following the magnitude 6.3 earthquake in the same region in 1963, seismic hazard in this segment has significantly decreased.

Conversely, the western part of Istanbul has not experienced a major earthquake in the past 500 years. Current fault drift measurements confirm this historical gap.

The most active seismic period in the Marmara Sea over the past 500 years was the 20th century, during which earthquakes migrated from west to east, causing six tremors with magnitudes exceeding 7. The intervals between major earthquakes in the region range from 89 to 163 years.

İSTANBULDA BÜYÜK DEPREM ÇOK ZOR
İstanbulun doğusunda, Adalar Fay segmentinde gelişen 1509 ve 1766 depremlerinin tahmini büyüklüğü M 6,8-7,2 dir (Ambraseys,2000). 1963 Adalar depremi M 6,3 olduğuna göre bu segmentin deprem tehlikesi oldukça azalmıştır.
İstanbulun batısında son pic.twitter.com/rLK1RHehTo

— Prof. Dr. Osman Bektaş (@profobektas) February 14, 2025

Recent seismic events near the Greek island of Santorini have intensified concerns. Since January 28, 2025, the region has recorded over 400 earthquakes, with the strongest reaching a magnitude of 4.8. These tremors have been concentrated approximately 25 km northeast of Santorini at depths between 5 and 25 km. 

The Disaster and Emergency Management Authority (AFAD) has classified this as an earthquake swarm, drawing parallels to similar activity recorded between 2011 and 2012, which did not result in volcanic eruptions.

On February 4, 2025, a series of earthquakes, including two of magnitude 5.1, struck the Greek islands, primarily affecting Santorini. Over 200 tremors have been recorded since the weekend, prompting authorities to evacuate more than 6,000 people. Schools have been closed, and residents have been advised to avoid large indoor gatherings. Experts have confirmed that the current seismic activity is tectonic rather than volcanic.

Türkiye’s most catastrophic earthquake in recent years occurred on February 6, 2023, claiming over 53,000 lives and injuring more than 107,000 people. The disaster, which struck southeastern Türkiye and northern Syria, was one of the deadliest earthquakes in the country's history.

By Tamilla Hasanova