GNGTS 2019 - Atti del 38° Convegno Nazionale

422 GNGTS 2019 S essione 2.2 Fig. 1 - Engineering-geological map of the northern and western sectors of the Island of Ischia. Sites cited in the text: 1) Piazza Maio, 2) Grande Sentinella and Fundera, 3) Panza, 4) Rotaro-Tabor Mts, 5) Zaro, 6) Mount Epomeo, 7) Citara, 8) Fango. Campotese-Panza); lava domes and plateau (Zaro); cliffs, slopes and piedmont relieves of Mount Epomeo (Fig. 1). The bedrock is composed by basal lavas (older than 75 ka), and by an overlying multi- layered succession from the Monte Epomeo Green Tuff, to submarine epiclastic sands and clays, the Citara Tuff and younger lavas (Zaro, Fundera). Soil cover units are represented by sub-aerial pyroclastites, widespread epiclastites re-sedimented from older volcanites, ancient landslides (mostly debris flow and avalanches), and coastal-alluvial plain deposit. Active landslides, mostly rock falls along the Epomeo slopes and coastal cliffs, and soil liquefaction represent expected earthquake-induced instabilities. The great heterogeneity of the cover units derived from the robust dataset is reflected on the significant variability of dynamic parameters, such as the Vs (Fig. 2). Plotting parameters with depth was particularly useful for the construction of the dynamic subsoil model. A sub selection of the entire dataset Fig. 2 - Plot of Vs with depth around the median value of the Vs for selected sand-sized and gravel-sized lithotypes. Over-imposed with the same colour and at a representative depth, distributions of Vs as whisker plots (minimum, 25th percentile, median, 75th percentile and maximum) are shown. Labels refer to selected units represented on Fig.1.