Lava flow volume and morphology from digitised contour maps: a case study at Mount Etna, Sicily

The volume and morphology of a lava flow-field can be measured by mapping and comparing the topography before and after lava emplacement. Contour maps are a widely available source of topographic data, containing a record of the geomorphological changes at volcanoes due to lava emplacement. This paper explores the use of 1:25,000 scale digitised contour maps for mapping two lava flows of diverse eruption history and morphology at Mount Etna, Sicily. We find that subtracting DEMs created from these maps gives a good representation of volume and shape for thicker lava flows (>10 m mean thickness) in the case of the 1983 lava flow. However, thinner (<10 m) flows, e.g., the 1981 flow, are not represented on this scale of map and the technique cannot be used. Hence, caution is required in using this technique. The assumption of accurate representation of modified topography in contour maps may not always be valid.