Fractal dimension in Italy: a geomorphological key to interpretation

摘要

By applying fractal geometry to Italy's coastline, with its differing geology and geomorphology, we were able to calculate the fractal dimension both of the whole coast and of some coastal sectors as well as highlight the geomorphic processes strictly related to its evolution. We analysed six different coastal sectors, subdivided along regional tectonic lines, which delimit zones of different tectonic styles, and on the basis of the physiography of the Tyrrhenian, Adriatic and Ionian margins (north-western and north-eastern Italy, Puglia and Calabria) and lastly on the basis of the physiographic singularity of the two larger islands (Sardinia and Sicily). For the different coastlines examined, our results showed that Italy's more or less straight present-day coastline has an average fractal dimension slightly above unity. Thus, we may suppose that, overall, the coastline has experienced concurrent overlay of secondary marine modelling processes, mostly resulting from erosive wave action and active morphoselective processes in different climatic conditions from today's, on primary tectonic processes, responsible for the present structure of coastal landscapes. In general, tectogenesis was more intense in the Pliocene-Pleistocene epoch, whereas morphogenests occurred in the late Quaternary. The different fractal degree of the various sectors would indicate that coastal evolution at certain moments was controlled by postglacial eustatic fluctuations, at others by more or less intense effects related to Pliocene-Quaternary tectonic events and to Pleistocene-Holocene volcanic activity; in recent and historical times, such phenomena appear to have been overlain by coastal dynamics.