Stress State Evolution in Glacially Imprinted Landscapes

The morphological evolution of alpine landscapes during the Quaternary climate cycles is tightly linked to the redistribution of gravitational stresses and the (in)stability of the rock mass. In this study, we investigate the evolving stress states of mountain massifs as they transition from fluvial to glacial topography and through subsequent rapid deglaciation. Using a three-dimensional numerical model based on the fictitious domain method, we compute stress distributions across complex, glaciated, and glacially imprinted landscapes. Time series of these stress calculations identify  when and where shear stress concentrations emerge within the mountain massif throughout its geomorphic evolution.

Our preliminary results quantify the contribution of two primary drivers of stress redistribution on mountain massif scale: 1) The transition from V-shaped fluvial valleys to U-shaped glacial troughs operates on time scales of 10⁵-10⁶ years and causes valley widening and deepening. This process steepens valley flanks and sharpens ridgelines, thereby concentrating gravitational loads and consequently increasing shear stresses. 2) Ice unloading due to climate warming and deglaciation (time scales of 10³ years) causes a rapid loss of lateral confinement previously provided by ice. This process increases shear stresses in valley flanks.

Both the transition from fluvial to glacial topography and the subsequent removal of ice act in combination to increase shear stress on valley flanks. When these shear stresses exceed the strength of the rock mass, failure occurs as a trigger of landsliding in paraglacial environments. By integrating topographic evolution, shear stress redistribution, and rock mass strength, this approach provides new insights into the long-term morphological evolution of mid-latitude mountains while serving as a predictive tool for identifying regions approaching critical rock failure.