4-4-4-4-4-4-4-4-4-4-4-4-4 From: Simon Thivet <Simon.Thivet@xxxxxxxx> *EGU Scientific Assembly 27 April-2 May 2025* We invite submissions to our session * "**Understanding tephra hazards: the contribution of field measurements, analog experiments, and numerical modeling*â?? *Group and session: Natural hazards â?? Volcanic hazards (NH2.7)"* *Abstract:* Tephra pose significant hazards to human health, infrastructure, and the environment, especially in regions surrounding active volcanoes. Assessing tephra hazards requires knowledge of the physical processes governing tephra generation, dispersal, and fallout, obtained through a multidisciplinary approach that combines field observations, experimental data, and computational models. For instance, field measurements play a critical role in gathering real-time and post-event data on tephra fallout, particle size distribution, and deposit thickness, providing ground-truth data that helps refine models. Recent developments in remote sensing and drone technology are also enhancing the time and spatial resolution as well as the accuracy of tephra transport and deposition processes. Meanwhile, analog experiments offer controlled environments to simulate eruptive processes, plume dynamics, and wind interactions, shedding light on the behavior of tephra during different eruption phases. These experiments allow us to improve our comprehension of ash aggregation and sedimentation processes such as Settling-Driven Gravitational Instabilities (SDGIs). Numerical modeling, driven by field and experimental data, allows for detailed simulations of tephra dispersal and fallout under various eruption scenarios and atmospheric conditions. Advances in computational power and algorithm development are improving the precision of models, allowing us to tackle challenging physical factors such as unsteadiness, particle-turbulence interactions, variable entrainment, thermal disequilibria, ash aggregation, and compressibility. Models enable better forecasting of ash cloud trajectories and deposition patterns. Models also assist in risk assessments, providing insights into potential impacts on aviation, agriculture, and urban areas. This session welcomes any contribution and advances on the aforementioned points related to tephra hazards, potentially emphasizing the synergy between fieldwork, analog experiments, and numerical modeling. *Abstract submissions due 15 January 2025, 13:00 CET:* *https://meetingorganizer.copernicus.org/EGU25/sessionprogramme <https://urldefense.com/v3/__https://meetingorganizer.copernicus.org/EGU25/sessionprogramme__;!!IKRxdwAv5BmarQ!Ygou4USHrUaQ64jxUpsbtD-HO4XWsVZ_SNatj_wgUH5EsDE0bwo17JBMjV4tXaiPsIxlFM24wRx61QwxAiVYoxxKrQ$>* *Conveners:* Dr. Simon Thivet Dr. Jonathan Lemus Dr. Allan Fries (Université de Genève, Geneva, Switzerland) 4-4-4-4-4-4-4-4-4-4-4-4-4 ------------------------------
