A 5.8 magnitude earthquake shook Istanbul on Thursday but authorities said no immediate damage was reported in Turkey's financial and cultural center.
Turkey's Disaster and Emergency Management Authority said the earthquake struck in the Sea of Marmara at 1:59 p.m. (1059 GMT) at 7 kilometers (4.4 miles) deep.
The official Anadolu news agency, quoting the Istanbul governor's office, said there were no reports of damage. Turkish media showed children being evacuated from schools and city residents waiting outside their homes.
Turkey is crossed by fault lines and is prone to earthquakes. In 1999, A 7.4 magnitude earthquake in western Turkey killed more than 17,000 people.
Experts have long warned a major earthquake is expected to hit Istanbul, Turkey's most populous city with more than 15 million residents.
A smaller earthquake of 4.6 magnitude was felt in Istanbul on Tuesday.