A 7.8-magnitude earthquake hit near Gaziantep in southeastern Turkey on Monday, the US Geological Service said.
The quake struck at 04:17 am local time (0117 GMT) at a depth of about 17.9 kilometres (11 miles).
According to AFAD, the government’s disaster management agency, the quake’s magnitude was 7.4.
The USGS reported another shallow 6.7-magnitude quake occurring near the site of the first about 15 minutes after.
The southern region of Gaziantep — one of Turkey’s key industrial and manufacturing hubs — borders Syria. The tremors were felt in Lebanon, Syria and Cyprus, according to AFP correspondents.
Turkish authorities have not yet reported any deaths or injuries, but videos posted on social networks showed destroyed buildings in several cities in the southeast of the country.
Turkey is in one of the world’s most active earthquake zones.
Duzce was one of the regions hit by a 7.4-magnitude earthquake in 1999 — the worst to hit Turkey in decades.
That quake killed more than 17,000 people, including about 1,000 in Istanbul.
Experts have long warned a large quake could devastate Istanbul, which has allowed widespread building without safety precautions.
A magnitude-6.8 quake hit Elazig in January 2020, killing more than 40 people.
And in October that year, a magnitude-7.0 quake hit the Aegean Sea, killing 114 people and wounding more than 1,000.