Mapping of tecto-lineaments and investigate their association with earthquakes in Egypt: a hybrid approach using remote sensing data

Abstract

This study integrates quantitative methods to detect surface and near-surface geological linear structures from digital elevation model. A set of altitude, slope and shaded relief maps was enhanced by applying Sobel filter with 10% threshold and percentile stretch to detect geological fractures and their displacements over regional scale. Topographic fabric grain algorithm, which classifies point lines into the ridge/valley and quantifies the degree to which all the ridges and valleys are aligned in the same direction, was used to auto-detect lineaments. About 1300 linear features were computed and their orientations were statistically analysed using rose diagrams. The enhanced morphometric maps successfully visualized fault zones and their displacements and detected the regional fault zones cutting across the entire Egypt. Their trends were found to be in the NE–SW, NNE–SSW, NW–SE, NNW–SSE, N–S, E–W and WNW–ESE directions. The results obtained using the integrated methods were compared with those in geological and seismic maps of Egypt and showed strong agreement in several places. This proposed method may be useful for mapping concealed geological structures, where geophysical surveying is difficult and geological information not available.