The first 7.8 magnitude quake occurred at 04:17 am (0117 GMT) at a depth of about 18 kilometres (11 miles) near the Turkish city of Gaziantep, which is home to around two million people, the US.
President Bashar al-Assad is seeking political advantage from an earthquake that has devastated large parts of Syria and Turkey, pressing for foreign aid to be delivered through his territory as he aims to chip away at his international isolation, analysts say.