Pliocene to Quaternary activity of the Sveta Nedelja Fault in Northwest Croatia as revealed by geomorphological analyses

Northwest Croatia is a seismically active region located at the junction of the Eastern Alps, Internal Dinarides, and the Tisza mega block of the Pannonian Basin System. The area is shaped by the slow convergence of the Adriatic microplate and Eurasian plate (3–4.5 mm/year), driving complex Cenozoic tectonics and Pliocene-Quaternary transpressive fault activity. Among the active faults, the Sveta Nedelja Fault (SNF) is particularly understudied, despite its  seismogenic potential. Positioned along the southern front of Mt. Žumberak, the SNF separates Triassic-Cretaceous carbonates in the north from Miocene basin deposits in the south.  

Geomorphological analysis was conducted to investigate the structural characteristics and tectonic activity of the Sveta Nedelja Fault (SNF). The study included the construction of swath profiles perpendicular to the fault strike to examine variations in topography and identify gradients indicative of structural deformation. Detailed mapping and analysis of drainage patterns, particularly in the Konšćica sub-basin, were performed to assess fault-related geomorphic features such as vertical steps, knickpoints, and convex stream profiles. 

Reconstruction of second-order drainage systems across the fault was undertaken to estimate potential displacements and identify alignments of streams and wind-gaps. This approach provided insights into both long-term tectonic processes and recent activity associated with the fault. These methods collectively aimed to delineate fault kinematics and assess its impact on regional landscape evolution. Future work will focus on quantifying deformation rates, employing age dating, geophysical and paleoseismological methods to better constrain the timing and extent of Quaternary fault activity. These findings are critical for understanding the neotectonic evolution of the Žumberak region and assessing seismic hazards, particularly in light of the 2020 Zagreb and Petrinja earthquakes, which underscore the urgent need for comprehensive seismic hazard assessments in Northwest Croatia.