An earthquake measuring 5.2 on the Richter scale hit northwestern Turkey today and was felt in Istanbul.
No injuries or damages were reported following the quake, which comes only days after another quake of the same size in the area.
The earthquake's epicentre was in the Sea of Marmara, which lies alongside Istanbul, and the shocks were briefly felt in Turkey's largest city of 12 million residents.
On Friday another small quake hit the province of Balikesir, which lies across the Marmara from Istanbul, but there were no injuries.
Turkey, which lies on a major fault line, suffered a devastating earthquake in August 1999, when nearly 18,000 people were killed.
Scientists have predicted a major earthquake is likely to hit the country in the next 30 years.