Quantifying Gas Hazard with VIGIL (Automatized Probabilistic VolcanIc Gas DIspersion Modelling)

Volcanic gas emission represents a source of hazard to humans and the environment. They occur both during volcanic unrest, eruptions and in quiescent stages of the volcanic activity. Therefore, it is a widespread and frequent threat. Many gas species (e.g. CO2, SO2) can affect human health and even threaten life at concentrations and doses above species-specific thresholds. Depending on the relative buoyancy at the emission location, volcanic gas emissions can be generally classified as dilute passive degassing and dense gas flow. Numerical simulations of gas dispersion involve a workflow that can be complex and time-consuming, since it starts with the modelling of the wind field, proceeds with the gas dispersion simulation and ends with the postprocessing stage. This process should be repeated several times (hundreds to thousands) for probabilistic volcanic hazard applications, in which the uncertainty of the relevant input parameters (e.g. wind field, emission rates and source locations) is explored to obtain probabilistic outputs. Here we present VIGIL, a Python simulation tool that manages the gas dispersion simulation workflow and is interfaced with two dispersion models: a dilute (DISGAS) and a dense gas (TWODEE-2) dispersion model. We show results from different applications showcasing the various capabilities of VIGIL.