Combining minero-petrological and geomorphological analyses at active volcano-tectonic and hydrologically hazardous areas: a case study on Montagnone-Monte Cito at Ischia (southern Italy).

The combined use of minero-petrological analyses and drone photogrammetry may represent a powerful way to better understand the dynamics of hazardous geological environments. This can help to map, investigate and monitor volcanic structures that are modifying by actual processes, particularly through the creation of a time series of spatial data able to evidence the geomorphological evolution and mechanical features variation of landscapes.

In this study we investigate the relationships between acid sulfate weathering, geostructural framework and geomorphological changes that can be observed at active volcanic hydrothermal systems. The investigated area is Montagnone-Monte Cito, site of high temperature geothermal activity, flank instability and disastrous seismicity in historical and recent times. The target area, in fact, is the one closest to the city of Casamicciola, remembered as the epicenter of the destructive volcanic-tectonic event (approx. magnitude 4.0) which took place on August 21, 2017 and was unfortunately destroyed by a powerful landslide on November 26, 2022.

Photogrammetry of proximity survey, geological field campaign, mineralogical and geochemical analysis with Optical Microscopy (OM), X Ray Diffraction (XRD), Electron Microscopy and Energy Dispersive microanalysis (SEM-EDS), and handheld X-Ray Fluorescence (XRF) to characterize altered outcropping deposits, were repeatedly carried out in the area. We present multitemporal analysis based on the comparison of 3D data obtained by UAV photogrammetry techniques. We comparison two dataset acquired in 2022 for each of which we obtained a 3d point cloud, that has provided the setting of the area at the different times and its evolution through their comparison evaluating volumetric changes.

Modifying sites have been examined in the field and characterized for mineralogical and geochemical features. Our methodological approach appears promising to evaluate evolution and rock fall susceptibility of solfataric terrains subjected to hydrothermal dynamics.