Volcanic eruptions are spectacular displays of nature’s incredible power, but they put local communities at risk. Approximately 800 million people worldwide live within 100 km of a volcano that is currently erupting or has the potential to erupt in the future. Our ability to mitigate their hazard relies on empirical analyses of monitoring data, with large uncertainties in estimating the probability of an eruption and its impact.

Forecasting the size, duration and hazards of eruptions requires a deep understanding of magma transport and storage and quantifying the timescales of the processes occurring beneath the surface. The relationship between these sub-surficial processes and geophysical and geochemical observations made at the surface is key to understand volcanoes behaviour.

The minerals within the rocks erupted during volcanic eruptions are an incredible archive of information. They act like a probe into the volcano’s interior, allowing us to decode its behaviour and inform volcanic hazards assessment. Drawing from examples of some of the most active volcanoes in the world – such as Popocatepetl and Colima in Mexico, and Stromboli and Etna in Italy – this talk will take you on a journey inside the volcano factory, exploring the hidden processes that drive eruptions.

Stromatolites are layered sedimentary structures formed under the influence of microbial communities and environmental factors. They constitute amongst the oldest known evidence of life on Earth – over 3.4 billion years old – and provide a unique fossil archive spanning nearly all of geological time. In this seminar, I will invite you on a journey through the Microbialite Collection of the Muséum national d’histoire naturelle (Paris), a unique archive to explore: • How do stromatolites record the oxygenation of Earth’s atmosphere and oceans? • What can they tell us about the diversity of ancient surface environments? • Are the rhythmic laminations driven by biological processes… or by climate cycles? • Do these layered structures truly reflect biological activity? • And how can AI help distinguish biogenic from abiotic laminated rocks? At the intersection of geochemistry, palaeontology, and astrobiology, my research seeks to improve our understanding of how life has shaped the sedimentary record; with implications that extend beyond Earth’s history to the search for life on other planets.

Turbidity currents, gravity-driven sediment-laden flows, govern material transport and shape underwater landscapes across diverse environments. While extensively studied in marine settings, their behaviour in freshwater systems remains underexplored. We present multi-temporal, multi-scale observations from the Aare Delta of Lake Brienz (Switzerland), combining Acoustic Doppler Current Profiler measurements with high-resolution repeated bathymetric surveys to capture turbidity currents and the resulting lake bottom changes. We document the upslope migration of a bedform triggered by a single flow event, demonstrating how discrete turbidity currents can rapidly reshape the channel floor. We further place these observations within a broader geomorphic context using a rare 125-year bathymetric time series. This longer-term perspective reveals how turbidity currents influence channel morphology over centennial scales. Together, our results highlight the value of lacustrine settings as accessible, scaled-down natural laboratories that bridge the observational gap between controlled experiments and deep-ocean canyons, offering new insights into turbidity-current processes.

Organic matter is expected to be a key component of bodies formed in the outer regions of planetary systems. In the Solar System, measured moments of inertia, interpreted with equations of state for ices, silicates, and carbonaceous materials, suggest that organics may constitute a major fraction of the refractory interiors of several icy bodies (e.g., Reynard & Sotin, 2023; Delarue et al., 2026). Organics may therefore exert a first-order control on thermochemical evolution and volatile production—an idea that is particularly timely given the growing population of low-density exoplanets. The presentation will summarize recent work aiming at (i) predicting the occurrence of organic-rich volatile worlds from host-star elemental abundances, and (ii) quantifying the impact of carbon/organics on thermochemical evolution. On the occurrence side, stellar abundance patterns are used to identify systems in which the available refractory and volatile budgets favor carbon-rich/organic-rich condensates beyond the relevant condensation fronts. On the interior side, evolution is modeled by combining equations of state for ices, silicates and carbonaceous materials with kinetic descriptions of the transformation of a representative organic compound as a function of time and temperature. The kinetic scheme tracks the progressive loss of H and heteroatoms from the carbonaceous phase, the associated increase in residual carbon density toward graphite-like values, and the production of mobile volatiles. These processes feed back on the thermal history and set the time-dependent inventories of potentially releasable species. Model outputs are used to quantify expected volatile release for Titan-like bodies and carbon-rich exoplanets, and to contrast these outcomes with classical telluric and ice–silicate evolution pathways. Implications for JWST-era characterization of low-density planets, and for joint constraints from mass–radius measurements, stellar abundances, and interior evolution models, are discussed.

Abstract to be provided.