According to the BBC, while no immediate casualties or major damage have been reported, authorities remain on high alert.
Turkey’s emergency services reported that the quake, which hit at 12:49 local time (09:49 GMT), originated at a shallow depth of 6.92 kilometres (4.3 miles).
The epicentre was located in the Silivri district, along the Sea of Marmara coast, approximately 80 kilometres (50 miles) west of central Istanbul.
Officials confirmed that two smaller quakes were recorded in the same region, followed by several aftershocks that continued to rattle nerves throughout the day.
“I was with my family in a high-rise building when the shaking started,” Selva Demiralp, an economics professor at Koç University, told the BBC.
“It was quite scary… We are safe and there seems to be no damage, but people are worried this could be a foreshock.”
Residents described the tremor as one of the most intense felt in recent years, with some reporting furniture and household items falling to the floor.
Social media videos showed people evacuating apartment blocks and gathering in open areas.
Municipal officials have begun inspecting buildings for structural damage and are urging citizens to avoid potentially compromised structures.
The quake stirred painful memories of the devastating twin earthquakes that hit southern Turkey in 2023, claiming over 55,000 lives.
Istanbul, a sprawling metropolis of 16 million people, sits just 20 kilometres north of the highly active North Anatolian Fault Line, making it especially vulnerable to seismic activity.
Emergency response teams remain on standby, and authorities are continuing to monitor the situation closely.
