Shallow Magma Storage Beneath Mt. Etna: Evidence From New Attenuation Tomography and Existing Velocity Models

Abstract

We present a new three-dimensional (3D) image of attenuation beneath Mt. Etna volcano based on the coda normalization method. Mt. Etna is an ideal natural laboratory for the application of new or unconventional tomography techniques owing to high levels of seismicity spanning a wide range of epicentral distances and depths. We retrieved seismic waveforms from the database generated in the 2014 TOMO-ETNA seismic experiment and performed a joint interpretation of tomographic and geophysical inversion models to better constrain interpretations of the volcanic structure. We compared the attenuation tomography results with seismic inversion models (two P wave seismic models and a 3D coda wave seismic attenuation model) and the literature to highlight and interpret structural elements and their impact on the volcano dynamics. We created a new image of the inner structure of Mt. Etna that will help to constrain present and future volcanic behavior. In particular, we focused on magma storage below the summit area and identified a large high-attenuation volume that is characterized by physical properties compatible with the presence of magma and other fluids. The existence of such a large volume of magma in the shallow crust below Mt. Etna has implications for the eruptive potential of the volcano.