Processamento di immagini landsat per l'interpretazione strutturale in aree tettonicamente attive: Un esempio dal margine sud-occidentale della catena del Gran Sasso

Abstract

A low sun elevation Landsat Thematic Mapper image of Abruzzi area was digitally processed for structural studies. An edge enhancement consisting of high-pass filtering the image with a 9x9 kernel, adding back the original (unfiltered) data, was performed to enhance textural differences while maintaining the albedo variations. The Optimum Index Factor technique was then used to choose the best band combination for False Colour Composite generation. Successive interpretation of the enhanced image showed a noticeable improvement in the detection of subtle structural features. The area that the Landsat image refers to is characterized, from a geomorphological point of view, by the presence of small depressions, rather narrow and averaging 1+2 km in length. These depressions are bounded by faults with NW-SE direction, responsible for the deformation of quaternary breccias. The edge enhanced image illustrates the changes in the average direction of the depression systems, going from NW to SE; thus resulting in an overall arc-shaped and sigmoydal trend. In order to explain the morpho-structural situation, as presented above, hypothetical model of deformation is proposed. This model takes into consideration left-lateral strike-slip movements due to faults with NE-SW direction.