Integrated Modeling of Magnetic, Gravity and Deformation Data at Etna Volcano: Intrusive Mechanisms of the Recent Eruptions

Geodetic, gravity and magnetic investigations have been playing an increasingly important role in studies on Mt. Etna eruptive processes. Although there have been numerous attempts to independently model these geophysical data, no investigations have been carried out to jointly interpret these observations. They are generally interpreted separately from each other and the consistency of interpretations coming from different methods is qualitatively checked only a posteriori. Such a lack of multidisciplinarity and integration of observations and theoretical studies has been certainly prejudicial to the development of a deeper understanding of the volcano dynamics. During ascent magma interacts with surrounding rocks and fluids, and almost inevitably crustal deformations, gravity anomalies and disturbances in the local magnetic field are produced. When the cause of their variations can be ascribed to the same volcanic source, a joint inversion of ground deformations, gravity and magnetic data would be advisable in order to identify the source parameters with a greater degree of accuracy. In order to make the estimation of source parameters more robust we propose an integrated inversion from deformation, gravity and magnetic data that leads to the best possible understanding of the underlying geophysical process. The inversion problem was formulated following a global optimization approach based on the use of Genetic Algorithms. The proposed modeling technique was applied on field data sets recorded at Etna during the last decade. For the different recent eruptions occurred here, the joint modelling not only allow the timing of the intrusive events to be described in greater detail but also, together with other volcanological evidences, permit some constraints to be set on the characteristics of propagation of shallow dikes.