Morpho-structural analysis of active volcanic calderas coupling high-resolution remote sensing and numerical modeling

Volcanic calderas are large, circular depressions formed by the partial or complete evacuation of magma reservoirs through eruption or magma migration. Active calderas represent significant hazards, from catastrophic eruptions during their formation to unrest periods characterized by changes in seismicity, degassing, and ground deformation. Beyond their hazards, calderas are of societal importance as hosts of geothermal energy resources and ore deposits. Understanding caldera volcano-tectonic models requires reconstructing volcanic structures and analyzing resurgence and subsidence processes. Morpho-structural surveys play a key role in this task but are often hindered by younger deposits, vegetation cover, and anthropogenic modifications. To address these challenges, this study focuses on two resurgent calderas: Ischia Island (Gulf of Naples, Italy) and the Los Potreros Caldera part of the Los Humeros Volcanic Complex (Trans-Mexican Volcanic Belt, Mexico). High-resolution morpho-structural analyses were performed using shaded relief images derived from drone-based LiDAR digital terrain models (DTMs). This advanced remote sensing technique provided precise bare-earth elevation data and enabled detailed mapping of structural architectures in active volcanic and seismic settings. A novel computational workflow was developed to process LiDAR data, removing vegetation and buildings to generate DTMs with centimetric resolution. These methods significantly improve deformation quantification and refine existing volcano-tectonic models. On Ischia Island, neotectonic mapping revealed fault geometries in the Casamicciola area, historically affected by destructive earthquakes such as the 1883 event (over 2,300 fatalities). These fault structures were incorporated into numerical simulations using the mantle and lithosphere dynamics code ASPECT. Simulations evaluated the influence of fault strength, geothermal gradients, and mechanical contrasts under three scenarios: (1) regional NE-SW extensional stress, (2) resurgence driven by magmatic intrusion pressurization, and (3) subsidence from magma depressurization. Results indicate that shallow magmatic intrusions (~2 km depth) are the primary drivers of Holocene deformation, with minimal contribution from regional tectonics. Modeled cumulative slip rates (5.0–31.12 mm/yr) align with geological estimates, and velocity profiles highlight how magma geometry, pressure, and volume control asymmetric caldera uplift. In Los Potreros Caldera, structural mapping constrained fault geometries associated with resurgence, delineating five structural domains linked to distinct magmatic and volcanic processes in the caldera’s evolution. Fault existence and behavior were confirmed through clear morphological expressions, complemented by geometric and kinematic field data. These findings provide new insights into the interplay between magmatic processes, fault dynamics, and seismic hazard in resurgent calderas, while demonstrating the potential of drone-based LiDAR and numerical modeling for advancing volcano-tectonic understanding.