The 1935 Erdek–Marmara Islands earthquake occurred at 16:41:30 local time 4 January on the islands of Marmara and Avşa off Erdek in the Sea of Marmara, Turkey.

Three aftershocks occurred in conjunction with this destructive earthquake that was felt strongly in Istanbul, Edirne and İzmir.

The foghorn building on Hayırsız Island was demolished and rocks at the shore fell into the sea.

[5] The submarine communications cable running across the Sea of Marmara remained intact.

In the villages Narlı and Ocaklar on the Kapıdağ Peninsula, and as well as around Avşa, fountains dried and emitted noise.