Barone, Andrea (2021) Integrated multi-scale methods for modeling the deformation field of volcanic sources. [Tesi di dottorato]

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Abstract

The modeling of volcanic deformation sources represents a crucial task for investigating and monitoring the activity of magmatic systems. In this framework, inverse methods are the most used approach to image deforming volcanic bodies by considering the assumptions of the elasticity theory. However, several issues affect the inverse modeling and the interpretation of the ground deformation phenomena, such as the inherent ambiguity, the theoretical ambiguity and the related choice of the forward problem. Despite assuming appropriate a priori information and constraints, we are led to an ambiguous estimate of the physical and geometrical parameters of volcanic bodies and, in turn, to an unreliable analysis of the hazard evaluation and risk assessment. In this scenario, we propose a new approach for the interpretation of the large amount of deformation data retrieved by the SBAS-DInSAR technique in volcanic environments. The proposed approach is based on the assumptions of the homogeneous and harmonic elastic fields, which satisfy the Laplace's equation; specifically, we consider Multiridge, ScalFun and THD methods to provide in a fast way preliminary information on the active volcanic source, even for the analysis of complex cases, such as the depth, the horizontal position, the geometrical configuration and the horizontal extent. In this thesis, firstly we analyse the biharmonic general solution of the elastic problem to state the deformation field surely satisfy the Laplace's equation in the case of hydrostatic pressure condition within a source embedded in a homogeneous elastic half-space. Then, we show the results of different simulations by highlighting how the proposed approach allows overcoming many ambiguities since it provides unique information about the geometrical parameters of the active source. Finally, we show the results of Multiridge, ScalFun and THD methods used for the analysis of the deformation components recorded at Okmok volcano, Uturuncu volcano, Campi Flegrei caldera, Fernandina volcano and Yellowstone caldera. We conclude this thesis by remarking the proposed approach represents a crucial tool for fixing modeling ambiguities and to provide useful information for monitoring purposes and/or for constraining the geometry of the volcanic systems.

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