The North Anatolian Fault stretches around 1,500 kilometres across northern Turkey, from the eastern highlands near Karlıova toward the Aegean Sea. It accommodates the westward escape of the Anatolian Plate as it is squeezed between the colliding Arabian and Eurasian plates.
It is a right-lateral strike-slip fault with a slip rate of roughly 2 centimetres per year, often compared to the San Andreas for its length, speed and behaviour. The fault is remarkable for its westward-migrating sequence of ruptures, in which successive earthquakes have progressively broken adjacent segments over the twentieth century.
The devastating 1939 Erzincan earthquake (magnitude ~7.9) began a cascade of major quakes marching west toward Istanbul, culminating in the 1999 İzmit earthquake (magnitude ~7.6) that killed more than 17,000 people. Seismologists consider the segment beneath the Sea of Marmara, close to Istanbul, a serious future hazard.