Quaternary mass movements controlled by a structurally complex setting in the central Apennines (Italy)

The paper discusses the results of an engineering-geology study of an area in central Italy affected by complex gravity induced slope instability. A finite-difference analysis was implemented to demonstrate that stratigraphy and recent tectonics have had a crucial impact on the gravitational processes that have occurred in a built-up area of the central Apennines (Italy). The creation of a reliable geological-evolutionary model proved to be a key tool for subsequent development of a numerical model, capable of elucidating the main factors and parameters controlling slope instabilities. The study area, in the vicinity of the small mountain village of Micigliano (central Apennines), displays extensive outcrops of carbonate platform lithotypes, hemipelagic marly-clayey deposits and arenaceous pelitic turbidites. Its tectonic setting is very complex, with intense faulting (thrusts, normal faults, and complex kinematic faults) and folding. A geological-evolutionary model of the instability processes in the various sectors of the study area was formulated and fine tuned, on the basis of detailed geological and engineering-geology surveys, assumptions on the mechanical and hydraulic characters of the local geological bodies, and observation of the morpho-evolutionary processes. Subsequently, a stress-strain analysis was applied to the model, using the finite-difference method, in order to reconstruct the complex mechanisms governing evolution of the various sectors of the investigated slopes and the effects of gravity-caused instability on the exposed lithotypes. The numerical model also helped to validate the consistency of the stress-strain assumptions with the deformation mechanisms observed in the various investigated sectors of the study area, yielding a kinematic picture of the causal factors of the local gravity-caused instability in space and time.