The North Aegean Trough is a deep, elongated marine basin in the northern Aegean Sea that carries the westward continuation of the North Anatolian Fault as it enters Greek waters. It is a transtensional structure where right-lateral strike-slip motion combines with extension to pull the basin open.
The trough accommodates a large share of the westward escape of the Anatolian block, slipping at around 2 to 3 centimetres per year, among the fastest rates in the region. Its steep submarine slopes and active faults make it a productive source of offshore earthquakes north of the Greek islands.
Major events attributed to this system include the 1968 Ağıos Efstrátios earthquake (magnitude ~7.1) and repeated strong shocks felt across the northern Aegean coasts of Greece and Turkey. Because it links directly to the Marmara segment, the trough is central to understanding how strain is transferred toward Istanbul and the Aegean.