Geomorphological Approach to Cliff Instability in Volcanic Slopes: A Case Study from the Gulf of Naples (Southern Italy)

Abstract

This paper deals with the problem of cliff stability and proposes a geomorphological zonation of a cliff using a sector of the Posillipo promontory (named the Coroglio-Trentaremi sea cliff, Italy), in the Campi Flegrei coastal area, as a case study. A detailed geological and geomorphological analysis was carried out, by combining field work with analysis of detailed scale topographic maps, orthophoto, and stratigraphical data from deep boreholes. Field and borehole data, together with structural data collected in seven different stations along the cliff, allowed us to derive six geological cross-sections and to reconstruct the complex stratigraphical and structural setting of the cliff. Geomorphological analysis focused on the detection of the main geomorphological factors predisposing to cliff instability. We selected the most significant factors and divided them into two groups: factors influencing landslide intensity and factors influencing cliff instability. Then, by means of a heuristic approach, we constructed a matrix that was used to derive a map showing the geomorphological zonation of the sea cliff. This map may enable to development of a reliable scenario of cliff instability and consequent retreat, which may be useful either to plan intervention works in the most critical areas or to organize prevention plans aimed at risk mitigation.

Geomorphological and Structural Assessment of the Coastal Area of Capo Faro Promontory, NE Salina (Aeolian Islands, Italy)

“…In this context, the geomorphological evolution induces a rapid cliff retreat, which triggers rockfalls and topples exploiting the discontinuities network [5][6][7] in the volcanic rock mass (e.g., joints and faults). Techniques in all fields of geology have been already explored in similar cases in the southern Italian peninsula [8][9][10][11][12][13], to define the hazardous conditions that could even provoke injuries or fatalities. Assessing these conditions, it is possible to find the best solution to address the risk mitigation measures or to fix them where they become ineffective, in a broad scenario of coastal management [14][15][16].…”

A combined approach to cliff characterization: Cliff Stability index

“…1), such as the Twelve Apostles (Australia), the Minamijima Island (Japan), the Pigeon Rocks (Lebanon), the Catedral (Peru), the Darwin Arch (Ecuador), the Portada (Chile), the Arco de Cabo San Lucas (Mexico), the Holei Sea Arch and Sunsent Cliffs (United States), the Perce Rock (Canada), the Hvitserkur (Iceland), the Cliffs of Moher (Republic of Ireland), the Arch Rock in Arnarstap (Ireland), the Stacks of Duncansby, Yesnaby and Thirle Door (Scotland), the Green Bridge (Wales), the Durdle Door, Flamborough Head and Old Harry Rocks (England), the Azure Window (Malta), the Drangarnir (Faroe Islands), the Porte d'Aval (France), the Quebrada coast, Cuevas del Mar beach and Cathedral beach (Spain), or the Ponte da Piedade (Portugal), among others. Numerous works have studied erosion problems on cliff coasts over the last decades (Sunamura, 1977;Robinson, 1977;Jones and Williams, 1991;Komar and Shih, 1993;Shih and Komar, 1994;Duperret et al, 2002;Moore and Griggs, 2002;Sallenger Jr et al, 2002;Rosser et al, 2005;Hansom et al, 2008;Dawson et al, 2009;Hapke and Plant, 2010;Lim et al, 2011;De Rose and Basher, 2011; Barlow et al, 2012;Dickson et al, 2013;Carpenter et al, 2014;Jones et al, 2015;Johnstone et al, 2016;del Río et al, 2016;Pappalardo et al, 2017;Earlie et al, 2018;Prémaillon et al, 2018;Westoby et al, 2018;Terefenko et al, 2018Terefenko et al, , 2019Zelaya Wziatek et al, 2019;Alessio and Keller, 2020;Muñoz-López et al, 2020;Di Crescenzo et al, 2021). For example, Sunamura (1977) proposed, based on field and laboratory data, a rel...…”