A suggested method for assessing cliff instability susceptibility at a given scale (CISA)

This paper illustrates a new multidirectional method for assessing cliff instability susceptibility at a given scale (CISA, Cliff Instability Susceptibility Assessment) through a case study along the Murgia coastline North of Bari (Apulia, SE Italy). The stretch of coastline considered in this study shows an indented rocky coast with cliffs up to 12 m high, numerous small to mediumsized caps and inlets, and a well protected tourist port. The coastal outcrops are made up of Mesozoic carbonate rocks which are thicklybedded (0.2-1.0 m) and, moderately to highly fractured and karstified. At places, clear signs of coastal erosion are evident; they consist mainly of rock falls caused by differential erosion of rock strata of varying resistance to weathering and sea wave action on the cliff face. The CISA method is based on classifying coastal sectors using above all morphological criteria and characterising them estimating and combining 28 incidence parameters according to an heuristic approach. These parameters were divided in four categories: geomechanical (12), morphological (6), meteo-marine (8) and anthropogenic (2). For each parameter 5 classes of rating were proposed; the cliff classification, in terms of cliff instability susceptibility, was obtain from the total rating which represents the summation of the single rating of the individual parameter.