Temporally variable creep behavior on the East Anatolian Fault and the arrest of the 2023 Pazarcık earthquake rupture

The 80 km-long, NE-striking Pütürge segment of the East Anatolian fault in eastern Türkiye is bounded by two earthquake rupture zones. In the NE, it is underlain by the rupture zone of the M6.7 2020 Sivrice earthquake; at its SW end, it truncates close to the northeastern extent of the M7.8 2023 Pazarcık earthquake. There is a substantial gap of over 40 km between the two rupture zones. Previous authors (e.g. Çakir et al., 2023) have suggested that the 2020 event was arrested by creep on the NE Pütürge segment. In this study, we investigate whether the Pazarcik event was similarly arrested by creep at the Pütürge segment's SW end.

We process InSAR data from ascending and descending tracks of the Sentinel-1 satellites that cover the Pütürge segment, from three time periods – before, between, and after the two earthquakes – using the ISCE and MintPy software. We take short, fault-perpendicular profiles through the velocities and time series we produce to investigate possible shallow creep behavior, and downsample the cumulative displacements to constrain models of fault slip. 

We find: 1) the Pütürge segment was creeping at the surface before the Sivrice earthquake (in the period 2014-2020), at rates that peak at ~6 mm/yr at its NE end, and decrease along-strike to effectively zero at its SW end; 2) the deformation following the Sivrice event includes ~10 cm of surface creep between February and July 2020 along the Sivrice rupture zone, followed by a M~5.8 aftershock and creep transient on the fault immediately to the SW of that zone; and 3) the post-Pazarcık earthquake deformation (~10 cm of surface creep in 8 months) is concentrated along the SW-most section of the Pütürge segment, where there had been little creep before or after the Sivrice earthquake. As we identify creep along the whole Pütürge segment, albeit at different times in different places, we suggest that creep did plausibly play a role in ending the Pazarcık rupture.