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

120 PATA Days 2024 RESULTS PHOTOGRAMMETRY: The Digital Elevation Model (DEM) obtained (Figure 2A) reveals areas with notable elevation changes, starting at an average of 607 meters and reaching 620 meters within less than 100 meters, forming a slope with an approximately 7-degree inclination and a southwest orientation on average. Perpendicular topographic lines drawn across these changes depict an anticlinal feature, originating from compressive forces. Based on this observation, the Porotoyacu Fault was traced in the DEM, spanning 700 meters in length. It exhibits non-linearity as it cuts through the area where residential structures are situated. Fig. 5: Regularization process. A) L-Curve. It is based on the mean square error (RMS) and includes a vertical smoothing of 1 and a horizontal smoothing that varies from 0.3 to 1.0 for each line. 50 iterations were performed to obtain the optimal model. This process indicates that all start from the same value, so the final selected model is correct. B) The RMS convergence. It is displayed on the vertical axis, while the L2, L1, and Infinity norms are represented on the horizontal axis. These norms are used to adjust the optimal velocity model, based on the data observed in seismic refraction. It is worth noting that this model is inferred from the horizontal smoothing parameters, as indicated at the inflection point for AB at 0. 9 represented by black arrows. SEISMIC TOMOGRAPHY: The seismic profile (Fig. 6) shows that the seismostratigraphic units exhibit a coherent deformation pattern, suggesting that identical events and structural elements are responsible for deformation in all units. In the southwestern (SW) part of the seismic profile, the structures exhibit a concave-down geometry in the regions where deformation is most pronounced. Interestingly, the axial lines of these concavities are not vertically aligned between units. This unique deformation configuration is interpreted to be caused by faulting. In this context, a main fault has been identified, referred to as the Porotoyacu. This fault exhibits a reverse regimen and presents a notable characteristic: its angle intensifies starting from -16 meters in depth. In parallel, an antithetic fault has been detected. Unlike the Porotoyacu Fault, this fault exhibits a normal régimen.