He won a state scholarship to study natural sciences abroad, as part of Mustafa Kemal Atatürk's plans of modernizing the newly formed Republic of Turkey.

Ketin returned to Turkey in 1938, and started his career as assistant professor at the Geological Institute of Istanbul Technical University.

Through a faithful coincidence, the long-dormant North Anatolian fault awoke to activity, first gently with the Tercan quake of 21 November 1939, but then violently with the great Erzincan catastrophe of 28 and 29 December 1939, which claimed the lives of some 32.000 people.

After Ketin published his paper on the North Anatolian fault, its importance was acknowledged when he was awarded the coveted Gustav-Steinmann-Medaille, the highest distinction the Geologische Vereinigung e.V.

Ketin contributed four major papers to the International Tectonic Map of Europe, published in 1960, in which he portrays Turkey as a dominantly asymmetric orogen, accreted from north to south.