Istanbul
Turkey's Interior Minister Suleyman Soylu tweeted there were no immediate reports of casualties or damage.
The quake struck at 09:37 am (0637 GMT), Turkey's Disaster and Emergency Management Directorate said. It was felt in several neighbouring provinces.
Turkey is crisscrossed by major fault lines and earthquakes are frequent.
In January, a 6.8 magnitude earthquake struck Elazig, killing 41 people in that province and neighbouring Malatya.
Another deadly quake struck western port city of Izmir in October, killing 116 people.
Turkey's worst quake in decades came in 1999, when a pair of strong earthquakes struck northwest Turkey, killing around 18,000 people.
Visit news.dtnext.in to explore our interactive epaper!
Download the DT Next app for more exciting features!
Click here for iOS
Click here for Android