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

1B) (Costa et al., 2020). Evidence and ruptures associated with a specific fault have been conducted in a trench south of Tena. These findings, displaying SSE and SSW orientations, are directly linked to the Porotoyacu Fault (Cornejo, 2020). This study aims to cartograph the Porotoyacu Fault on a local scale and determine its subsurface geometry in a southern section of the Porotoyacu fault by employing aerial photogrammetry and seismic refraction tomography (Vp wave). This section is located in the vicinity of the fault trace and shows possible deformations (Fig. 2A). METHODS PHOTOGRAMMETRY: This process covered an area of 0.388 km² (Fig. 3A) using a DJI Phantom 4 RTK drone. Due to limited equipment limitations, control points were not used in this study. The photogrammetric process was carried out using Agisoft Metashape software. A total of 432 images were processed, of which 429 were correctly oriented. A rotation angle of yaw, pitch, and roll was applied. For orientation, maximum precision was used and a generic preselection was applied. Stationary tie points were not excluded and guided matching was not used. Depth maps were generated using low-quality parameters and moderate filtering due to the capacity of the equipment. In addition, a dense point cloud was created with 8,892,697 points. For the classification of terrain points, a maximum angle of 7 degrees, a maximum distance of 0.1 m, and a cell size of 25 m were established (Figure 3B). Finally, a Digital Elevation Model (DEM) was generated with a size of 3,904 x 4,487 using the dense point cloud as the data source (Fig. 2A). Fig. 1: Location of the study area (A) Geodynamics of Ecuador. The green polygon represents Ecuador within the broader geodynamic context of South America, where the Nazca Plate subducts beneath (Hasterok et al., 2022). The study area is delineated by a red dot. (B) Map of the Porotoyacu Fault. The topography of the study area is depicted on a Red Relief Image Map (RRIM), a technique developed by Chiba & Hasi (2016) using a Digital Elevation Model (DEM) from ALOS PALSAR DEM. The fault trace provided by the SARA Project is visible as a black line (Adapted from Costa et al., 2020). The Porotoyacu Fault area is highlighted within a yellow rectangle, while the white rectangle represents the specific study section where the proposed methodologies were performed. The colored dots indicate the seismic activity until 2022, classified by magnitude (MW) (IGPN, 2022).