160 Years of Etna summit craters through a photogrammetry-based time machine

This study presents a quantitative, multi-temporal assessment of Etna’s summit morpho-structural evolution, spanning a 160-year (1865–2024) period. We integrated historical topographic maps with modern, high-resolution remote sensing data, including Unoccupied Aerial System surveys. Dataset-specific validation and statistical error propagation yielded root mean square errors ranging from decametric values for the earliest cartographic sources to metric values for the post-2020 datasets. The resulting topographic time series was interpreted alongside geological observations and previously published geodetic analyses. This integrated reconstruction documents the transition from a predominantly monocentric summit configuration to a highly dynamic polycentric system, and reveals contrasting morpho-structural behaviours among the four summit craters. VOR is characterized by recent constructive growth, BN and NEC by recurrent infilling followed by subsidence, whereas the SEC exhibits persistent constructive growth accompanied by progressive eastward expansion. These differences are consistent with variations in crater position, structural setting, shallow feeding-system configuration, and dominant eruptive style. The long-term evolution of the summit area is also consistent with the influence of the North-East and South Rift zones, and with published geodetic observations describing the seaward deformation of Etna’s eastern flank. Overall, the reconstructed evolution highlights the interaction between volcanic construction, structural controls, and gravitational deformation in shaping a continuously changing and asymmetric summit system. The proposed geospatial workflow provides a reproducible and transferable framework for integrating heterogeneous historical and modern topographic datasets and for investigating long-term morpho-structural change at other highly active volcanoes.