Abstract

Earthquakes can deeply shape the mountainous landscape through co-seismic landslides, generating large amounts of sediment that are then transported and distributed by rivers, controlling the landscape evolution. This influence is observed in the Liquin similar to e-Ofqui Fault System (LOFS), an active intra-arc fault system extending hundreds of kilometers through the Andes in Chilean Patagonia. For example, on April 21, 2007, a 6.2 Mw earthquake in the Ayse ' n Fjord triggered over 500 landslides with volumes reaching 12-20 Mm3. Although there is a well-defined recurrence time, no study has focused on the effects of co-seismic landslides and sedimentary dynamics on the evolution of this mountainous landscape. In this research, we seek to improve the long-term understanding of the interaction between landslides and fluvial incisions in this segment of the Andes. For this reason, we implemented the HyLands landscape evolution model to simulate landslide activity coupled to fluvial incision. We consider the landslides that occurred during the 2007 earthquake as a precedent and simulate nine scenarios of ten seismic cycles over 21,000 years based on the 2100-year recurrence time documented in this region for the Holocene. We further used multiple uplift rates, sediment erodibility, drainage area, and channel slope exponent ratios (m/n) associated with the stream power law to assess the parameterization's impact on the landscape. According to our results, earthquake-induced landslides are a fundamental mechanism in the landscape's evolution in this region. Deposits from landslides can create transitory landscape forms that can intervene in fluvial dynamics. A significant part of the landslide sediment can remain on the slopes for thousands of years. We identified that parameterization considerably impacts the evolutionary response of the landscape in the evaluated time scale. Low m/n ratios can generate a different evolutionary response than other scenarios because the slopes are constantly driven towards their threshold angle, intensifying the interaction between landslides and fluvial incisions. Based on our analysis and considering the seismic history of the Ayse ' n Fjord, we can explain a critical primary control of the LOFS on landscape erosion and sediment production. Implementing a hybrid landscape evolution model can help to infer the contribution of sediments associated with large earthquakes and improve the understanding of the role of landslides in the evolutionary history of Andean Patagonia. However, we stress that it is essential to advance in capturing erodibility and incision parameters of the stream power law in the Andes and local geomechanical information. Finally, we believe the landscape evolution models can help to deepen the knowledge of these processes in other Andean basins exposed to these