Alberto Salerno

Lava flow dating is a fundamental aspect of volcanology, contributing to the understanding of eruption histories, hazard assessment, and volcanic evolution. Traditional dating methods, such as radiometric techniques, provide high precision but are often costly, time-consuming, and limited to accessible sites. Recent advances in satellite remote sensing offer a powerful alternative for estimating lava flow ages over extensive and often inaccessible volcanic terrains. Multispectral and hyperspectral imaging enables the detection of mineralogical and chemical changes that occur as lava flows undergo weathering and oxidation over time. Among the most relevant indicators of lava flow aging is the oxidation state of iron, which transitions from ferrous (Fe²⁺) to ferric (Fe³⁺) forms as a function of exposure to atmospheric and environmental conditions. The Sentinel-2B satellite, part of the Copernicus program, provides high-resolution multispectral data suitable for capturing these spectral variations. This study presents a novel methodology for estimating the relative ages of lava flows by leveraging Sentinel-2B imagery and GIS-based processing. The approach involves the development of a custom toolbox within ArcGIS Pro, named "Polygrid," designed to preprocess satellite images by removing vegetation and moisture effects. Additionally, spectral band ratios are utilized to highlight Fe²⁺ and Fe³⁺ distributions, facilitating the construction of a Fe³⁺/Fe²⁺ ratio image for age estimation. The results are validated against known eruption dates to assess the accuracy and reliability of the proposed method. This study focuses on four volcanic regions characterized by diverse geological settings and well-documented eruption histories: Mount Etna (Italy), Stromboli (Italy), Kīlauea (Hawaii), and the Grindavík region (Iceland). These locations were selected due to their frequent lava flow activity and availability of independent age constraints for validation.