ISTANBUL, Sept. 24 (Xinhua) -- An earthquake with a magnitude of 4.6 hit Turkey's biggest city Istanbul on Tuesday, but no casualties have been reported so far.
The tremor happened in the Marmara Sea off the Silivri district at 11:00 a.m. local time (0800 GMT), the Disaster and Emergency Management Authority said in an announcement posted on its website.
At a depth of 5.36 km, the quake caused panic in the metropolis of 16 million, but no damage was detected so far, the Istanbul governor's office said.
The Sozcu daily said some schools across the city were evacuated due to rising security concern.
Geologists have long been expecting a strong earthquake to hit Istanbul in the fault line passing under the Marmara Sea.
Speaking to the NTV broadcaster, Serif Baris, a geophysics engineer, said the tremor is not a foreshock of the expected strong earthquake in Istanbul.
In 1999, a strong earthquake shook the Kocaeli province, 100 km east of Istanbul, killing around 17,000 people.