Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

No distinct fault trace was detected. Instead, we observed a localized deformation zone, represented by Unit 5 (Fig. 3), which we interpreted as a fault zone. Unit 5 is visible not only in the logged trench wall but also extends continuously along the trench floor and into the opposite wall. Its strike aligns with the scarp trace, and the deeper anomalies detected in the geophysical profiles This led us to delineate the presumed faults that confine the occurrence of Unit 5. Scarp diffusion modeling Assuming that the present-day shape of the scarp primarily depends on the passage of time and κ value, we calibrated the coefficient of diffusion using the Sub-Tatra fault scarp for the Western Carpathians setting. For linear diffusion modelling of this scarp, we selected two sites covered by colluvium material with an assumed age of 15 ka (Pánek et al., 2020). The best- fit curve, determined by the smallest root mean square error (RMSE) value, was chosen in each case. The results yielded a mean κ value of 2.5 ± 0.8 m²/ka. Across the 10 investigated topographic profiles, the coefficient of diffusion ranged from 1.3 to 3.9 m²/ka. The estimated mean κ value was applied to the Brzegi fault scarp diffusion modelling. For subsequent calculations, we selected 15 topographic profiles and set an initial scarp slope of 90° due to the straight intersection line and strike-slip sense of the fault. Again, the best-fit modelled curves indicating scarp age, closest to the observed profile, were chosen based on the smallest RMSE value. The results indicate a range of 10 to 50 ka for the age of scarp formation, with an average value of 26.3 ± 14.5 ka. Fig. 3: The trench across the scarp in Brzegi, the red dash line bounds the dark gray unit 5.