Morphometric Analysis toward Mapping Relative Tectonic Activity of Lebanon

Abstract

Abstract The analysis of geomorphic indices, computed using a digital elevation model and a geographical information system, was carried out to look for signs of tectonic activity in the river basins of Lebanon. The tectonic activity analysis was conducted on the thirty-eight basins through two methods: (1) shape-based, which estimates topography (stream gradient, hypsometry integral, and valley floor), form (asymmetry factor and basin shape), and sinuosity indices (fractal dimension of drainage patterns and mountain front), and (2) terrain-based, which extracts terrain (stream power index, valley depth, flow width, and relief ratio), and surface fractal dimension complexity indices. The results obtained were combined to produce two Relative Active Tectonic Maps (RATMshape and RATMterrain). This study demonstrated that active tectonics matched well with the extracted geomorphic indices and allowed to define the relative tectonic activity in Lebanon: about 65% of the basins correspond to class 1 low; 28% to class 2 moderate; 5% to class 3 high; and 2% to class 4 very high. The east part of the Yammouneh fault and the entire Serghaya fault are moderate to highly active based on the relative tectonic activity analysis. The more active tectonic areas are concentrated in the north ends of Lebanon, while moderate tectonics are focused on the south ends. The entire Rachaya and Roum faults are low to moderately active. The northern part of the Lebanon mountain range, which sits west of the Yammouneh fault, has exceptionally high relative tectonic activity.