The assessment of volcanic hazards is crucial to develop effective emergency plans, especially for volcanoes close to urban centers or under air traffic routes. Impact assessment relies on underlying numerical codes that require eruptive source parameters as input and forecasts drastically depend on their robust reconstruction during ongoing events. We apply a novel deposit inversion workflow built on ensemble methods and data assimilation techniques to reconstruct the explosive events that occurred at Mt Etna, Italy, between 3 and 5 December 2015. Based on results from previous studies, we reconstruct this eruption using the Gaussian with Non-negative Constraints data assimilation method. Results agree well with independent observations and highlight the potential for automatized procedures in volcanic hazard assessment.