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

and exhibits an asymmetrical positive flower structure. The Río Cuervo Fault, a major NS-striking fault, lacks seafloor traces, suggesting recent activity occurred decades to centuries prior to 2007. The Quitralco Fault shows an estimated lateral offset of ~636 m. Other NE-SW striking normal faults were also identified, including the Cuervo Ridge Fault, Río Pescado Fault, Isla Mentirosa Fault, and Punta Mano Fault, displaying various degrees of deformation. Architecture of postglacial sedimentary infill in the inner aysén fjord The inner Aysén Fjord, bounded by the Cuervo Ridge and an associated bathymetric step, features a well-stratified sedimentary cover known as PLU that overlays MU. The PLUexhibits awedge-shaped architecture thinning towards the west, indicative of significant sediment contributions from the Aysén River during the last deglaciation and the subsequent global sea level highstand (~7 kyr BP; Lambeck et al., 2002). Sedimentary thickness varies from over 300 m near the Aysén River mouth to approximately 109 m near the CuervoRidge. The inferred age for PLU, based on local observations and tephra layers, is approximately 12 kyr, with average sedimentation rates ranging from25 to 9mm/ yr, assuming the removal of laminated sediments by the Aysén Glacier during the Last Glacial Maximum (LGM). A sediment core (MD07‐3117, Fig. 1) from the Aysén Fjord, analyzed by Van Daele et al. (2013) and Wils et al. (2018), revealed three sandy layers and a pumice layer, which were correlated with specific reflectors in SBP data. Van Daele et al. (2013) suggested sedimentation rates of about 3.0mm/yr, aligningwithearlier estimates (Salamanca & Jara, 2003) and dated the pumice layer to ~3,170 yr BP. Wils et al. (2018) confirmed these correlations with radiocarbon dating and identified five paleoevents ranging from 710–830 to 8,710–8,890 14C Cal yr BP. The oldest event, associated with the SL-A reflector, is dated between ~18,600 and 20,000 14CCal yr BP. Regional geomorphological evidence supports the presence of large ice sheets over the Northern Patagonian Andes during the Last Glacial Maximum (~20-18 kyr BP; Heusser, 1990; Thomson et al., 2010). Vargas et al. (2013) dated soils buried by tephra in the Aysén Fjord area to ~12,000 14C yr BP, marking the last ice sheet retreat locally. The absence of glacio-deformed sediment in the Aysén Fjord suggests that the sedimentary infill is entirely postglacial. Seismic profiles show moraine banks (MU) at ~200 m depth, with a minimum age of ~12,000 yr for the top of the MU, implying that the stratified sediment of PLU is postglacial. This interpretation revises earlier estimates by Wils et al. (2018), who dated reflectors at ~55 m b.s.f. to ~18-20 kyr based on sedimentation rates from surface cores. We propose that PLU comprises two subunits: a transgressive phase (PLUT) formed during deglaciation and a progradational phase (PLUP) developed after sea levelstabilization(~7-6kyrBP;Lambecketal.,2002,2014). The PLUT is characterized by high-contrast acoustic impedance, indicating coarser sediments. Radiocarbon data suggest the base of PLUP is located between 17-15.5 m in core depth, with sedimentation rates from ~12,000 to ~6,000 Cal yr BP estimated between ~15.6 and ~36.1 mm/yr. Rates for the period from 17.3 to 6 kyr Cal BP range from ~8.3 to ~19.1 mm/yr, reflecting contributions from ice-sheetmelt and sea-level rise. The lower rates in the Holocene are attributed to the progradation of the Aysén River and limited accommodation space due to global sea level stabilization (Lambeck et al., 2002). New efforts to refine the ages and understanding of glacial evolution along our transect in the Aysén Region have involved detailed stratigraphic analysis and radiocarbon dating of key glacial systems, including the Coyhaique Alto, El Diablo, and El Toro Systems (Villalobos et al., in progress; Fig. 2). We have integrated radiocarbon data from glaciolacustrine and fluvioglacial deposits across multiple sites to track the timing of glacier advances and retreats. This dataset allows us to test and refine the time-dependent evolution model for the Patagonian Ice Sheet proposed (e.g., Hubbard et al., 2005) to explains glacier fluctuations between 45° and 48° S. Through these efforts, we aim to constrain the ages of paleoseismic events by linking glacial landforms, such as submerged moraines in the Aysén Fjord and Lake Riesco, to sedimentary records and seismic profiles.