A fault in slow motion
The North Anatolian Fault (NAF) is a 1,500-kilometer-long, right-lateral strike-slip fault that slices across northern Turkey. It marks the boundary where the Anatolian Plate, to the south, grinds westward against the Eurasian Plate. This relentless motion, driven by the collision of the Arabian and Eurasian plates further east, averages about 20-25 millimeters per year. Most of this strain accumulates in locked sections of the fault, released suddenly and violently in major earthquakes.
Some segments, however, behave differently. The Ismetpaşa segment is an example where the fault moves through aseismic creep—a slow, steady slip that does not generate earthquakes. This creep releases a significant amount of the accumulated strain, with rates measured between 8 and 13 mm per year. This silent movement is continuously monitored by networks of high-precision GPS stations and satellite-based InSAR (Interferometric Synthetic Aperture Radar), which can detect surface deformation down to the millimeter scale. Data shows that even on this "creeping" segment, the slip is not uniform and may only occur in the upper 7 kilometers of the crust. Below this depth, the fault is likely locked, still accumulating stress.