Shear Strain Evolution Spanning the 2020 Mw6.8 Elazığ and 2023 Mw7.8/Mw7.6 Kahramanmaraş Earthquake Sequence Along the East Anatolian Fault Zone

Abstract

Shallow creep along strike-slip faults is essential in releasing strain during earthquake cycles. However, its origin—whether inherent or triggered by earthquakes—remains debated. Using Interferometric Synthetic Aperture Radar phase-gradient data, we map shear-strain rates along the East Anatolian Fault Zone (EAFZ) before and after the 2020 Mw6.8 Elazığ and 2023 Mw7.8/Mw7.6 Kahramanmaraş earthquakes. The observed strain-rate distributions strongly correlate with coseismic slips in the EAFZ. The stress-driven afterslip model constrained by the phase-gradient time series reproduces distinct decaying patterns of newly activated creeping segments, showing that rapid afterslip may decay slowly and keep slipping for decades. Our results reveal that large earthquakes can accelerate, expand, and trigger shallow fault creep, highlighting the roles of fault frictional properties and stress changes caused by nearby earthquakes. These findings provide new insights into fault creep mechanisms and their linkage to large earthquakes, with implications for faulting behaviors.