Insights on the multi-scale topographic features of Mt. Etna volcano (Italy)

The terrain analysis of volcanic landforms provides valuable qualitative and quantitative insights into the factors that shape volcanoes. Using different terrain analysis approaches, this study reconstructs and describes the multi-scale topographic features of Mt. Etna Volcano (Italy). Specifically, the first order shape of the volcano, approximating the large-scale volcanic edifice, is characterized through the analytical fitting of contour lines using an elliptical geometry. The geometric properties of this modelled surface align with the evolutionary phases of Mt. Etna over the past 300 kyr. The modelled surface also serves as a two-dimensional filter: the residual topography, obtained by its removal from the actual topography, reveals second-order topographic features. The residual topography is then opportunely resampled and analysed using the wavelet technique along slope-parallel and base-parallel sections. This analysis reveals zones with different wavelength behaviours that correlate with the residual topographic anomalies. The spatial arrangement of this anomalies around the flanks of the volcano aligns with known volcanic features of Mt. Etna, such as the “Ellittico” volcano and its caldera depression, the large volcano-tectonic depression of the “Bove” valley, and the unstable eastern flank. A few zones do not correspond to any recognized features and may suggest the occurrence of buried structures, offering potential targets for future investigation. This study demonstrates that the wavelet-based technique is a valuable tool for characterizing and classifying volcanic landforms.