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

historically reported and their documented effects (e.g., land- level changes, tsunamis, shaking) have been used to estimate their rupture locations and along-strike extents (Fig. 1). In addition, by applying dislocation models to the distribution of coseismic elevation changes, inferences about the downdip rupture location have been made (Cisternas et al., 2017). As historical reports may be deficient for certain areas and cover less than ~500 yrs, natural archives are required to adequately constrain the spatiotemporal variability of megathrust ruptures and assess the contribution of partial ruptures to the overall slip budget. Lake sediments can be used as natural seismographs, recording seismic shaking above a certain threshold, typically with a seismic intensity of ~VI-VII. Detailed mapping of the imprints of the 1960 and 2010 megathrust events revealed that the size and abundance of sedimentary imprints can be used to provide estimates of seismic intensity at lake sites (Van Daele et al., 2015). This information was applied on a transect of three lakes (39.2-39.8°S: Villarrica, Calafquén, Riñihue) showing a more modest imprint related to partial ruptures, compared to the giant 1960 and 1575 events (Moernaut et al., 2014). Here we extend the transect toward the south (until 41.3°S) by incorporating four new lake records (Ranco, Puyehue, Rupanco and Llanquihue) and adding a coastal tsunami record (Laguna Gemela West, 40°S) to gain insights into the location and characteristics of partial ruptures in 1837, 1737 and ~1460. Fig. 1: Setting of South-Central Chile with indication of paleoseismic sites (red), historical evidence (black) and inferred megathrust rupture history for the Valdivia Segment. Ruptures for the Maule segment are indicated in grey. The five new lake studies fill the data gap between 40-41.5°S. The sedimentary and historical data were modified after Cisternas et al., 2017 and Hocking et al., 2021.