Boğaziçi University's Kandilli observatory and Earthquake Research Institute says the quake struck on Thursday at 11:54 p.m. and had a magnitude of 5.1. It put its epicenter in Tekirdağ and Marmara Ereğlisi. The quake was largely felt in Tekirdağ, Çorlu and İstanbul.
The observatory also reported two minor aftershocks in Marmara Ereğlisi early on Friday.
Earthquakes frequently rattle İstanbul, but most are minor and cause little or no damage. The most recent devastating earthquake to strike İstanbul occurred in Aug. 17, 1999. A 7.6-magnitude tremor struck at 3:02 a.m. local time, killing tens of thousands of people.