An earthquake measuring 5.2 magnitude on the Richter scale hit in the Marmara Sea Monday evening, causing panic among the residents of Turkey's largest city Istanbul.

The Istanbul-based Kandilli Observatory reported the epicenter of the quake in the Marmara Sea at a depth of 15.3 km and a magnitude of 5.2.

The quake struck at 20:57 local time (17:57 GMT) in the Marmara Sea close to the town of Tekirdag, which is approximately 121 km west of Istanbul.

Three smaller aftershocks were also reported.

The first aftershock measuring 2.7 and the other two measuring 2.6 on the Richter scale, the Kandilli Observatory said. The depths for the first two aftershocks were recorded at 8.8 km and the third at 6.4 km.

No physical or material damage was incurred, according the governor of Tekirdag.

Turkey is fundamentally vulnerable to earthquakes because of its geographical location.

The country sits between two huge tectonic plates, Eurasia and Africa/Arabia, which are inexorably grinding into one another, north to south.

Earthquake safety was forced firmly on to Turkey's agenda following the Izmit tremors in 1999, which killed more than 17,000 people.