Can Geometrical Barrier Explain the Mw 7.8 Earthquake in Southern Türkiye on February 2023?

Two large-magnitude earthquakes hit southern Türkiye on February 2023. The first, Mw 7.8 strike-slip earthquake generated a rupture of 300 km section along the ∼600 km long East Anatolian fault (EAF). Here, we present an analytical solution using perturbation theory for the static stress field near the EAF induced by the fault geometry and the tectonic loading before these earthquakes. By applying the Coulomb failure criterion, we show that a large stress barrier is developed around the segment that ruptured in the first earthquake. Considering stress field conditions that are associated with left-lateral strike-slip on the fault, we demonstrate how the barrier location is mostly determined by the fault geometry, while its magnitude is sensitive to the background stress value and direction. We further show that the elastic energy around the fault increases to maximum values near the barrier region and decreases away from it. Therefore, we suggest that the high magnitude and the associated long rupture of the earthquake were strongly influenced by the static stress heterogeneity generated by the fault geometry.