Simulating pre-eruptive magma ascent and induced ground deformation with application to Campi Flegrei caldera, Italy.

Volcanic eruptions significantly impact populations and infrastructure near active volcanoes. They are often preceded by geophysical signals like ground deformation, seismicity, and changes in gravity, which help us understand the magma ascent process. However, interpreting these signals can be challenging, especially when multiple deformation sources overlap or when a volcano has not erupted for an extended period, leaving uncertainties about magma pathways and volcanic behaviour. A notable example is the Campi Flegrei (CF) caldera, which has shown signs of unrest in recent years. Given the potential for an impending eruption, it is essential for the scientific community to assist civil authorities in preparing for emergencies. One urgent requirement is the development of pre-warning scenarios that detail geophysical observations linked to magma ascent. Due to a lack of direct data, numerical models are necessary to simulate these observations. In this thesis, I propose a method to calculate magma ascent scenarios, with a focus on ground deformation. To model expected deformations, I first create a simplified stress field based on the morphology of CF. I then simulate the rise of dikes within this stress field, tracking their trajectory and evolving shape, while also determining the displacement field at GNSS monitoring stations. I add Gaussian noise to the simulated displacements and perform inversions using mathematical models. Additionally, I perform the inversions adding the contribution to the displacement field from the inflation of a surface hydrothermal system, calculated through a distribution of point sources, which is important in the case of calderas like the CF. This study establishes a method for calculating possible magma ascent scenarios and quantifies predicted displacements, enhancing our ability to detect and characterize the magma ascent phase. This can improve our ability to track rising magmas in a complex unrest situation.