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

486 PATA Days 2024 M E T H O D O L O G Y To investigate the submarine LOFS segments, we used high- resolution bathymetric and seismic reflection profiles collected in the inner fjord west of Puerto Aysén (73.13°-72.68°W, 45.32°- 45.47°S) during the DETSUFA project from March 4th to 17th, 2013, aboard the BIOHésperides. Bathymetric data were acquired using a KONGSBERG SIMRAD multibeam EM-1002S system, providing a 4 m grid resolution. Data processing was performed with Caris HIPS and SIPS software, with bathymetric maps created in ArcGIS. Seismic profiles were obtained using BOLT air guns and a DELPH SEISMICPLUS system, with post- processing in Seismic-Unix to migrate sea bottom diffractions and mute the water column, applying a P-wave velocity of 2000 m/s for migration. We analyzed seismic events from the 2007 Aysén Earthquake Sequence using local seismic network data from the Chilean National Seismological Center and the University of Liverpool, leading to a 3D seismotectonic model of the LOFS incorporating active fault structures and hypocenter clusters R E S U LT S The inner Aysén Fjord features a generally flat seafloor with slopes of ≤2.5°, steepening to 30°–80° along the fjord's northern and southern boundaries, and the Cuervo Ridge, which exhibits NE-striking bathymetric highs and slopes up to 80°. Depth ranges from 150 m near Bahía Acantilada to a maximum of approximately 340 m west of the Cuervo Ridge. Identifying submarine fault scarps is challenging due to high sedimentation from the Aysén River and deformation from landslides. Bathymetric highs show vertical displacements up to 8 m. Structures previously interpreted as fault scarps near Punta Cola are now linked to basin-plain deformation associated with mass flows (Van Daele et al., 2013). These bulges, resembling fold-and-thrust structures from landslides (Schnellmann et al., 2005), range from370 to 750m in length. The sedimentary infill was divided into three seismic-stratigraphic units based on subbottom profiler data (Fig. 1): the Cuervo Ridge Unit (CRU, chaotic seismic facies indicatinghardvolcanic rocks), theMoraine Unit (MU, interpreted as a glacial moraine), and the Parallel Laminated Unit (PLU, reflecting sedimentation from the AysénRiver). SevenMass Transport Deposits (MTDs) were identified, associated with submarine landslides, showing evidence of repeatedmass-wasting events. We describe active faults in the postglacial sedimentary infill, including the Punta Cola Fault, which extends 4.2 km underwater