The Digital Elevation Model of Italy for geomorphology and structural geology

Abstract

The geomorphological setting and main geo-structural features of the Central-Southern Italian Peninsula have been investigated by creating and analyzing a Digital Elevation Model (DEM) and derived slope, aspect and shaded relief images. The DEM has been assembled from the Mean Heights Archive, provided by the Italian Geological Survey for the whole country. The elevation data exhibit a grid mesh spacing of 7.5′' Latitude and 10′' Longitude. Firstly, three different methods for calculating from a DEM slope and aspect are discussed: the Four Contiguous Right Triangles, the Maximum Downward Gradient and the Bicubic Spline First Derivative; the resulting maps have been compared with each other at regional scale and for a small area with a slope map obtained by using classical techniques. The main goal of the comparison has been the choice of the best technique for the computation of the digital slope map of Italy. The Four Contiguous Right Triangles method yields better results, both at local and at regional scale, and is being used to create from the DEM a slope map and a shaded relief of the whole country, which will be published by the Italian Geological Survey. Secondly, the integrated analysis of DEM, derived slope digital map and shaded relief has permitted verification, for the Italian Peninsula, of the trends of already mapped fractures and faults and detection of previously unmapped structures showing morphological evidence. The analysis of 1520 regional structural features has showed that the morphological setting of the studied area is strictly related to the tectonics: about 90% of the mapped faults and folds are detectable on the shaded relief, which proved to be the most useful byproduct of the DEM for morphological analysis.