Locking Depth and Interseismic Slip Rate Analysis of the North Anatolian Fault Zone: Insights from Geodetic and Geophysical Techniques in the Düzce Region

Reliable determination of the fault locking depths and slip velocities is of great importance for the assessment of maximum magnitude of a potential earthquake and in performing seismic hazard analyses, especially on large earthquake-prone fault zones. The North Anatolian Fault Zone (NAFZ), a nascent transform plate boundary between the Eurasian and Anatolian plates is characterized by high stress accumulation. The east-west trending earthquake sequence, starting with the M7.9 Erzincan earthquake in 1939 and ending with the M>7 İzmit and Düzce ruptures in 1999 in the NAFZ, revealed a westward migration of seismic energy release. The 1999 M7.2 Düzce earthquake occurred 3 months after the 1999 M7.4 İzmit earthquake, drew a particular attention to the Düzce region as it occurred in the east, reversing the westward migration movement, and resulted in an eastward supershear rupture. In this study, we aimed to analyze the interseismic locking depth and the surface creep parameters in Düzce region by using geodetic and geophysical data. For this purpose, we first examined the spatio-temporal variation of the surface deformation along the Düzce Fault segment of the NAFZ in order to better understand the interseismic loading parameters, and possible effect of the creep. Therefore, we implemented the InSAR Small Baseline Subset time series analysis technique using Sentinel-1 InSAR data for both ascending and descending orbits from 2017 to 2022 to estimate horizontal and vertical displacements and also to calculate the locking depth. Consistent with the previous studies, our study showed that the slip rate in Düzce segment of the NAFZ was ~25 mm/yr. Besides, we incorporate various geophysical properties (e.g. geo-electric resistivity, seismic velocity) through previously obtained by 2D and 3D modeling of magnetotelluric and seismological observations with InSAR-based surface deformation in and around the study area to have an insight into the impact of petrophysical rock properties on seismogenic zone characteristics.
This project is funded by the Bogazici University with the BAP Project No SUP-18161.