GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.2 GNGTS 2023 Seismic imaging of the shallow eruptive pathways of Deception Island, Antarctica R. Guardo 1,2 , L. De Siena 2,3 , J. Prudencio 4 , G. Ventura 5 1 INGV – Bologna 2 TeMaS — Terrestrial Magmatic Systems Research Area, Johannes Gutenberg University, Mainz, Germany 3 Institute of Geosciences, Johannes Gutenberg University, Mainz, Germany, 4 Departamento de Fisica Teorica y del Cosmos, Universidad de Granada, Granada, Spain, 5 INGV – Roma Deception Island is one of the most active and best-documented volcanoes in Antarctica. Since its last eruption in 1970, several geophysical surveys have targeted reconstructing its magmatic systems. Here, novel data selection strategies and multi-frequency absorption inversions have been framed in a GIS. The result is the detection of these eruptive pathways and their spatial correlation with all available geological (vents and faults distribution), geochemical and geophysical knowledge of the volcano. The model offers the first image of the magma and associated fluids pathways feed the 1967, 1969, and 1970 eruptions. Results also suggest that future ascending paths might lead to active research bases and zones of planned helicopter rescue. The connection between seismic absorption, temperature, and hot fluid content makes it a promising attribute for detecting and monitoring eruptions at active calderas as well as the determination of shallow geothermal areas. We applied a multidisciplinary approach to a sub-dataset of the TOMODEC seismic experiment conducted inside the bay and offshore Deception Island (Ibanez et al., 2017; Prudencio et al., 2013). The method combines a detailed statistical analysis of the data designed for absorption tomography (Guardo & De Siena, 2022) with interpretations performed in a GIS environment. The original dataset is described and made available by Ibanez et al. (2017). The subset was used by Prudencio et al. (2013) to separate and map scattering attenuation from absorption using Gaussian sensitivity kernels. The selection process discriminated the best quality traces based on inversion-specific parameters (Guardo & De Siena, 2022). We describe differences for frequencies below (6 Hz, Figure 1) and above (15 Hz) the dominant frequency of theshots (12 Hz). We resolve several high-absorption anomalies within the bay and across the rim (Figure 1a). At 6 Hz, we recognize a similar NNW-SSE high-absorption trend in the two absorption maps (Figures 1a and 1b), within the low-velocity anomaly identified by Zandomeneghi et al. (2009) (Figure 1c). The highest-absorption anomalies remained undetected in Prudencio et al. (2013), with these authors