A 6.2-magnitude earthquake struck off the coast of Silivri in the Marmara Sea at 12:49 p.m. local time on April 23, sending tremors across Istanbul and nearby provinces in Türkiye.
According to the Disaster and Emergency Management Authority (AFAD), the quake occurred at a depth of approximately 7 kilometers (4.35 miles) and lasted 13 seconds.
The earthquake, which originated from a segment of the North Anatolian Fault Zone running through the central Marmara region, was felt in cities up to 300 kilometers from the epicenter.
As of 9:00 a.m. of April 24, a total of 266 aftershocks had been recorded after the 6.2 magnitude earthquake, of these, 258 measured between 0 and 4 in magnitude, 7 were between 4 and 5, and one aftershock registered above magnitude 5.
The AFAD stated that the aftershocks are largely concentrated along a 10- to 15-kilometer stretch east of the epicenter, especially near the northern edge of the Central Marmara Trough and close to the main fault line. The agency warned that these tremors could continue in the coming days and advised residents to remain alert.
The AFAD’s Earthquake Science Board, made up of experts from various disciplines, noted that the earthquake was consistent with a right-lateral strike-slip fault mechanism. Preliminary analysis shows that a fault segment approximately 15 kilometers long and 9.5 kilometers wide was involved in the rupture, with a lateral displacement of about 30 centimeters.
While no widespread structural collapses have been confirmed, officials from the Ministry of Environment, Urbanization and Climate Change are conducting on-site assessments. Over 10,000 calls have been made to the 112 Emergency Call Center, with 296 related to building damage.
Authorities urged citizens to avoid entering potentially damaged buildings until official inspections are completed. “Citizens with concerns about the safety of their buildings should report them to the emergency call center and avoid reentering until cleared by technical teams,” the AFAD emphasized.
The agency also called on the public to remain calm and follow only official updates, cautioning against misinformation on social media. “We extend our well wishes to all residents in Istanbul and other affected provinces,” the statement concluded.