Istanbul authorities said they were still scanning the city and asked members of the public to not approach buildings that might be damaged.
A series of earthquakes have hit the Istanbul area, according to multiple reports.
As of 13:30 Istanbul time (10:27 GMT), there were no reports of any casualties.
Turkey's Disaster and Emergency Management Presidency gave details of the first three quakes, though at least three more sizeable tremors followed these quakes, according to local reports:
Quakes of up to five on the scale are felt and cause minor damage. Anything above a six is ranked as strong and can cause severe damage.
Istanbul authorities said they were still scanning the city and asked members of the public to not approach buildings that might be damaged.
Istanbul is situated near the North Anatolian Fault and is home to more than 16mn people.
Asked after the February 2023 disaster if Istanbul was well prepared for a massive earthquake, seismologist Kalafat told AFP: "I'd like to say it, but sadly, it's a very big city with too many poorly constructed buildings."
Kalafat had previously denounced using low-quality cement and building on "soft soils".