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

features result from an earthquake seafloor rupture, with notable fault slip along the northern segment of PCF, evident in profiles SL‐05 and SL‐06, as opposed to the southern profile SL‐07. The deformation includes local subsidence and vertical offset amplification, with secondary normal faulting at shallow depths. Shallow seismic profiles from 1995 (CIMAR‐1) did not show sea floor deformation in the PCF area (Araya‐Vergara, 2011), supporting our hypothesis of submarine earthquake rupture during the 2007 event. SBP SL‐05 and SL‐06 reveal a 650 m long escarpment with a ~2 m bathymetric change, parallel to the proposed QF fault trace. Contrary to Wils et al. (2018), who identified this escarpment as a 2007 event fault scarp, we interpret it as an ancient fault scarp covered by younger sediments, with the Mw 6.1 dextral-normal event likely not reaching the Aysén Fjord sea bottom. No surface rupture features associated with the 2007-AYSS are observed along RCF in our data, where the fault tip ranges between ~109.2 and 27.2 m b.s.f. The complex fault geometry in the fjord suggests multiple scenarios for paleo-earthquakes, either involving individual faulting with different recurrence intervals or multifaulting events driven by coseismic ruptures and static stress transfer. This is a similar to events in New Zealand and Mexico (Beavan et al., 2012; Fletcher et al., 2014; Hamling et al., 2017). Given average sedimentation rates of ~25 mm/yr from PLU (12 to 6 kyr Cal BP), we speculate that the seven identified paleolandslides, resulting from active fault ruptures, occurred approximately every 1,100– 1,500 years during the Holocene. These landslides, including the 1960 Mw 9.5 Valdivia earthquake's relatively small superficial slides (Wright & Mella, 1963) and the 2007 Mw 6.2 Aysén earthquake's larger deep-seated slides (Oppikofer et al., 2012), suggest that significant deep-seated landslides in the Aysén Fjord are linked to local ruptures rather than subduction zone events. Seismic migration and seismotectonic model Shallow earthquakes in the region, typically within the first 10 km of the upper crust, initially appear randomly distributed. A 4-D first order seismotectonic model reveals clusteredpatternsof seismicactivity. January2007showedtwo clusters near theQF trace, associatedwith different depths and magnitudes, interpreted as independent ruptures. February 2007 saw southwardmigration of seismicity, with two clusters linked to theRCF, and shallower activitynear the PCF. March 2007 concentrated seismic activity along the QF, while April 2007, despite being significant due to Mw 6.1 and Mw 6.2 earthquakes, showed reduced activity. in affected areas, possibly due to equipment damage. The period from May 2007 to February 2008 saw deeper seismicity and W-E migration, associated with E-W lineaments. A 3-D seismotectonic model integrates hypocenter clusters, focal mechanisms, and seismic profiles, showing fault planes consistent with Thomson’s (2002) model. The 2007‐AYSS may result from static stress transfer and seismic migration from ductile to brittle crust, explaining the observed seismic patterns. This model highlights significant seismic potential and together with the new fast-slip rates for LOFS (De Pascale et al., 2021) stress the necessity for more studies regarding the active nature and paleoseismic recording associated with this structures. A C K N O W L E D G E M E N T S We thank our colleagues for their assistance in this study, particularly the DETSUFA campaign crew aboard BIO Hespérides for providing seismic and bathymetric data. Villalobos's PhD research was funded by CONICYT National Doctoral Scholarship 15090013, and the DETSUFA survey was supported by project CTM2010- 09891-E. G. Lastras received support from the Catalan Government Grups de Recerca Consolidats grant (2014 SGR 1068). Field observations in Aysén were funded by FONDECYT Iniciación Grant 11160038, CIMAR-24 from CONA, and the U.K./Chile NERC-Newton Fund Grant NE/N000315/1.