The largest quake had a magnitude of 6.2 and struck the Marmara Sea 13 miles off the Turkish coast at 12:49 p.m. local time (5:49 a.m. ET), according to the United States Geological Survey. That was followed by at least three aftershocks between magnitudes 4 and 5, the USGS said, all clustered near the economic maritime artery of the Bosphorus Strait. The USGS’ “Did You Feel It?” map said it shook cities as far away as the Romanian capital of Bucharest and the Bulgarian capital of Sofia 300 miles away. But so far, Turkish officials have found no “damage or adverse conditions on our highways, airports, trains or subways,” according to Turkish Transportation and Infrastructure Minister Abdulkadir Uraloglu on X.

An earthquake with a preliminary magnitude of 6.2 shook Istanbul and other areas on Wednesday, Turkey’s disaster and emergency management agency said. There were no immediate reports of serious damage in the metropolis of 16 million. More than 150 people were hospitalized with injuries sustained while attempting to flee buildings, the Istanbul governor’s office said. The earthquake had a shallow depth of 10 kilometers (about 6 miles), according to the United States Geological Survey, with its epicenter about 40 kilometers (25 miles) southwest of Istanbul, in the Sea of Marmara.

"An earthquake of 6.2 magnitude occurred in Silivri, Sea of Marmara, Istanbul," Interior Minister Ali Yerlikaya said on X, adding that it was felt in the surrounding provinces. The initial quake struck at 12:49 pm (0949 GMT) at a depth of 6.92 kilometres under the sea, which lies to the south of the city, AFAD said. It was followed by eight others with magnitudes of 3.5 to 5.9. As buildings shook, people rushed onto the streets where crowds of worried-looking people stared at their mobile phones for information or made calls, an AFP correspondent said. "I just felt earthquake, I've got to get out," a shaken-looking decorator said while rushing out of a fourth-storey apartment where he was working near the city's Galata Tower, who did not want to give his name.