*4.4. Geomorphological Zonation of Instability along the Coroglio-Trentaremi Sea Cliff*

Overall geological, structural, and geomorphological data highlight the diffuse presence of landslides affecting the sea cliff. We propose, in Figure 12, a geomorphological zonation of the Coroglio-Trentaremi sea cliff, which highlights the location of areas more susceptible to instability. This geomorphological zonation is based on the evaluation of I

and W factors (Table 1), whose weights have been crossed according to the matrix reported in Table 2.

**Figure 12.** Geomorphological zonation of landslide magnitude along the Coroglio-Trentaremi sea cliff. M3: high magnitude landslide (hundreds to thousands of cubic meters involved); M2: moderate magnitude landslide (tens of cubic meters involved); M1: low magnitude landslide (few cubic meters involved). Arrows indicate areas subject to risk due to cliff edge retreat (green arrows), to the presence of sandy shore for mooring boats (red arrows) and to the presence of ships and swimmers (blue arrows).

> The map shows that the more diffuse magnitude class is M2 (e.g., moderate magnitude). High magnitude landslides (class M3 in Figure 12) are limited to few sectors of the Coroglio-Trentaremi sea cliff. These include portions of the sea cliff with high sea cliff height values, presence of a dense network of fractures, some of which are beating fractures, and with large caves at the base of the sea cliff. Low magnitude landslides (class M1 in Figure 12) include few sectors at the base of the sea cliff, occurring near Coroglio, the Trentaremi bay and the La Gaiola islet. In this area, the sea cliff height is low to very low and landslide bodies locally protect the sea cliff base from wave action.

> Sectors of the sea cliff where the presence of human activities may enhance landslide risk are limited to few portions of the Coroglio-Trentaremi sea cliff. These include both areas placed on top of the sea cliff edge and areas placed at the base of the sea cliff. On top of the sea cliff, the area with sport facilities at the Virgiliano urban park, to the west, and

the archaeological roman villae of Diana, to the east, are present (Figure 12). In both cases, cliff edge retreat due to landslide may cause several problems to both human activities and archaeological finds. At the base of the sea cliff, sandy shores for mooring boats are present, which may increase landslide risk especially in summer due to the increasing number of boats that attend this sector of the Campi Flegrei coastline.
