Newcastle also paid tribute, saying: “A talented player and a special person, he will always be missed by our players, staff and supporters.”
Atsu won 65 caps for Ghana and helped them reach the final of the 2015 Africa Cup of Nations, where they lost on penalties to Ivory Coast. He was last selected to play for Ghana in 2019.
He joined Chelsea from Porto in 2013 and had several loan spells at clubs including Vitesse and Bournemouth.
“Chelsea sends our heartfelt condolences to Christian’s family and friends and all those affected by the earthquake tragedy,” the London club said.
More than 45,000 people have been killed in the earthquake that struck Turkey and Syria, and the toll is expected to rise further, with some 264,000 apartments destroyed in Turkey and many still missing in the country’s worst modern disaster.