Magnitude Matters: examining landsliding magnitude-frequency relationships and their impacts on mountain landscapes

Susannah Morey, (she/her),University of Colorado Boulder Colorado, United States. susannah.morey@colorado.edu

Landslides are responsible for mobilizing enormous volumes of sediment from hillslopes into channels. At short timescales, these landslide deposits can change channel geometries and impact a system’s ability to efficiently export sediment. Mountain channels must mobilize this sediment before they can incise into their bedrock. There is evidence that mass failures like landsliding set an upper limit to relief and thus shape topography. However, few studies have investigated how landslides impact the landscape- and geologic-scale shape of landscapes. We aim to use topographic metrics to characterize how varying degrees of landsliding at geologic timescales shape landscapes. To address the long-term interplay between landslides, sediment dynamics, and the topographic evolution of Earth’s surface, we use landscape volution modeling which incorporates landslide triggering combined with river bedrock erosion, gravel transport that includes abrasion of both sediment load and bedrock, and dynamic channel adjustment consistent with that of near-threshold alluvial channels. We find that the inclusion of sediment attrition is necessary to reduce the flux of gravel and is consistent with inferences from field studies. We compare our model results to landscapes with constrained landslide histories among a spectrum of tectonic and climatic environments to assess our model’s ability to accurately capture realistic landscape features. This comparison enables us to explore the impact of future, rapid environmental climate change on landslide occurrence and risk, especially the influence of sediment supply on the cascade of downstream hazards

2025 CSDMS meeting-126

Magnitude Matters: examining landsliding magnitude-frequency relationships and their impacts on mountain landscapes