Annual to millennial landslide inventories and hillslope erosion in NW Argentine Andes

• Applicant: Professor Bodo Bookhagen, Ph.D.
• Subject Area: Palaeontology
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 356194137

This collaborative German-Argentine study focuses on understanding the occurrence of landslides in the NW Argentine Andes. This region is characterized by a steep E-W and a moderate N-S environmental gradient of changing climate and vegetation cover, in addition to pronounced contrasts in topography and relief. This region is tectonically active and has been affected by two earthquakes in the past 6 years (M6.3 in 2010 and M5.8 in 2015), i.e. within a timeframe covered by dense optical and radar-remote sensing data, and thus lends itself to a rigorous analysis of different forcing factors that influence landsliding. Hillslope processes, including large stochastic landsliding events, are critical to the morphologic evolution of mountain ranges, and are key to the generation and transport of sediment into sedimentary basins. While constructive tectonic forces are responsible for mountain building processes, physical (e.g., the cumulative effect of earthquakes) and bio-geochemical (e.g., weathering, biota) processes strongly impact sediment production and transport, and ultimately, the erosional decay of orogens. The role of landslides in this combination of processes, as rare, but often voluminous events, is not well understood. This is because the frequency of large landsliding events is often beyond instrumental records. While previous studies suggest that the temporal clustering of landslides may be explained by earthquakes and/or rainfall-extreme events, their spatial distribution is controlled by preconditioning factors such as rock fracturing and shearing, and environmental factors, including vegetation cover. Here, we set out to test hypotheses and model predictions that landslide location and mass-transport rates are to a large degree controlled by vegetation cover and geologic preconditioning factors. While earthquake and rainfall-extreme events and their potential impacts cannot be predicted yet, a more holistic understanding of the locations of landsliding will aid in assessing natural hazards in the changing environments of high-mountain terrains. In a second step, we hypothesize that geochemical tracers allow a more rigorous assessment of landslide occurrences. We will use geochemical tracers to measure landscape disequilibrium and investigate if present-day observations of landslide distribution can be extended into the past and into geological archives. For this purpose we will quantify millennial erosion rates and landscape disequilibria using in-situ and meteoric 10-Beryllium. This will be combined with remote-sensing data, to generate a landslide and hillslope instability time series for the past 15 years (2001-present day) and to ultimately elucidate the impacts of earthquakes, climate, and vegetation-cover changes on landsliding events.

• DFG Programme: Research Grants
• International Connection: Argentina
• Partner Organisation: Consejo Nacional de Investigaciones Científicas y Técnicas; MINISTERIO DE CIENCIA, TECNOLOGÍA E ; INNOVACIÓN PRODUCTIVA
• Cooperation Partner: Professor Dr. Fernando Hongn