Destructions left after an earthquake are mostly caused by high-frequency ground motion that originates from the seismic source. I will exploit the natural continuity between geodetic and seismological data to illuminate high-frequency sources and their relations with changes in earthquake rupture speed. I propose an innovative Bayesian 2-step kinematic inversion in the frequency domain to investigate these destructive and poorly constrained high-frequency sources. This probabilistic approach is based on near-field data and a detailed analysis of the model parameter uncertainties, which allows better locating the HF sources. The project will bring new insights into how high-frequency relates to tectonic features, both in subduction zones and large continental faults. ERASMUS will be a collaborative effort between different earthquake-related communities to generate knowledge that can be included in more reliable seismic hazard assessment, impacting society significantly.

How do erosion rates in glacial landscapes vary with climate change and how do such changes affect the dynamics of mountain glaciers? Providing quantitative constraints towards this question is the main objective of COLD. These constraints are so important because mountain glaciers are sensitive to climate change and their deposits provide a unique history of Earths terrestrial climate that allows reconstructing leads and lags in the climate system. The climate sensitivity of mountain glaciers is influenced by debris on their surface that impedes ice melting. Theoretical models of frost-related bedrock fracturing predict that rates of debris production are temperature-sensitive and that its supply to mountain glaciers increases during warming periods. Thus a previously unrecognized negative feedback emerges that lowers ice melt rates and potentially buffers part of the ice retreat due to warming. However, the temperature-sensitivity of debris production in glacial landscapes is poorly understood. Specifically, we lack robust erosion rate estimates for these landscapes, which are key for testing models of frost-related bedrock fracturing. Here, I propose an innovative combination of new tools that capitalize on recent developments in cosmogenic nuclide geochemistry, landscape evolution modelling, and planetary-scale remote sensing analysis. I will use these tools to quantify headwall erosion rates in mountainous glacial landscapes and to gauge the sensitivity of mountain glaciers to variations in debris supply. Expected results will provide a basis for assessing the impacts of global warming, for improved predictions of valley glacier evolution, and for palaeoclimate interpretations of glacial landforms. COLD will focus on glacial landscapes, but the inverse modelling approach I will develop is applicable to any landscape on Earth and has the potential to fundamentally transform how we use cosmogenic nuclides to constrain Earth surface dynamics.

Alumina and silica nanophases play a crucial role in rock weathering and their formation and destruction controls Earth’s response to global climate change. The presence of various products of aqueous weathering of aluminosilicates points to a complex activity of water, and is considered as the geological indication for the occurrence of life-habitable conditions. In this regard, a more complete picture of the water-alumina-silica interactions would allow for better specifying the molecular-level conditions for early life. Upon weathering the original Al- and Si-containing phases are dissolved at the solid-water interface, undergo hydrolysis and condensation reactions and form new colloidal nanoparticles. However, quantitative and mechanistic understanding of the underlying processes that lead to the formation and types of Al and Si phases is still lacking, due to the insufficient in situ methodology providing structural information about the colloidal species in solution. Therefore, the main objective of the NanoSiAl project is to develop, test and validate the methods for the direct in situ and real-time structural and kinetic characterisation of the alumina and silica colloid formation pathways at the length-scale of < 100 nm. I will achieve this by utilising state-of-the-art in situ liquid-cell transmission electron microscopy (L-C TEM) complemented with synchrotron-based scattering methods. This way I will be able to fully avoid the usual artefacts of sample varying and hard-vacuum conditions, because the L-C TEM and scattering methods allow for direct in situ characterisation of nano-sized objects in solution with a near-atomic-resolution. This combination of novel techniques will provide unprecedented insights on properties of the molecular building blocks for alumina and silica as they nucleate, grow and assembly with each other.

Repeated glacial-interglacial cycles during the Quaternary have significantly impacted the topography of many mountain ranges around the world. Yet, the response of landscape evolution to repeated climate oscillations has not been well quantified. In recently deglaciated landscapes, the transition from glacial to fluvial/hillslope processes have induced progressive topographic adjustments, and the large amounts of sediments inherited from glacial periods and generated through landsliding of oversteepened glaciated topography may act as a fundamental control on the incision of postglacial rivers. These sediments can enhance fluvial incision rate by providing more tools for erosion, or inhibit incision by armoring the river bed. Characterizing when and where sediment enhances or inhibits fluvial incision in postglacial landscapes is critical for understanding the changes in postglacial landscape evolution rates over time and quantifying the response times of mountain ranges to deglaciation. In this project, I propose to develop a landscape evolution model to account for the complex impact of sediment dynamics on fluvial incision in postglacial landscapes. I will utilize this model to investigate the response of fluvial incision to changes in sediment supply and assess the effects of sediment on postglacial landscape evolution. I will apply the model to quantify response times of the deglaciated European Alp, leveraging the rich observational datasets in this region. The proposed work will provide a quantitative understanding of postglacial fluvial incision histories, which is critical for ecosystem management and natural hazard assessment in recently deglaciated mid-latitude mountain ranges and perhaps in high-latitude mountain ranges where continued climate change may eventually lead to deglaciation.