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Abstract

Continuous acquisition of high quality geophysical data allows developing a comprehensive geodynamical picture of Mt. Etna and the adjacent areas. We focus on seismic and ground deformation data recorded in the time span 2002 to 2021. Ground deformation measurements on the western flank of the volcano reveal a general trend of inflation, which is an expression of volcano doming and progressive magma accumulation. The seismicity on Etna shows a rather heterogeneous picture. In general, hypocenter depths increase from SE towards NW. Besides, shallow events are frequent in the central part of the area. Focal mechanisms provide information about the forces acting in the seismic source and rupture orientation. We used unsupervised learning - Self Organizing Maps and K-means clustering - for the classification of 577 seismic moment tensors. In the shallow levels normal faulting is frequent. The dispersion of strike direction of the axes for these events mirrors the complex stress field caused by magma dynamics in the shallower portion of the plumbing system. P- and T- axes of deeper events – orientated radially and concentric with respect to the summit area - indicate the existence of a pressure source in the central part of the volcano. The volcano related stress field interferes with the regional field, partly overriding it. The prevalence of the former becomes evident by comparing strain release for volumes inside the volcano edifice to those for adjacent volumes. It is five to ten times larger than in adjacent areas even for the deepest layers.