Detection of recent faulting and evaluation of the vertical offsets from numerical analysis of SAR-ERS-1 images: the example of the Atacama fault zone in northern Chile

Catherine Mering, Jean Chorowicz, Jean-Claude Vicente, Cherif Chalah, Gaelle Rafalli, Joan B. Lurie, James J. Pearson, Eugenio Zilioli
1995 Geographic Information Systems, Photogrammetry, and Geological/Geophysical Remote Sensing  
Its is already well known that the relationship between the antenna depression angle of the incident beam and the surface slope of macro-scale features is very significant in the interpretation of radar Images. The foreslopes of topographic features (slopes facing the antenna) are responsible for strong echoes with the greatest amount of reflection occuring when the local slope is perpendicular to the mdar beam (Ulaby et al., 1982), which corresponds to a 67OC angle in the case of SAR ERS-l
more » ... es. This condition, known as normal incidence, produces a very bright area on the image. Abrupt scarps such as those of recent faults (see Fig. I ) which face radar illumination can be then considered as creating conditions for such a foreslope brightening . Besides, the presence of topographic relief in a scene can introduce distorsions known as foreshortening and layover. We will see whether the specific conditions of the viewing on Fault scarps are affected by these distorsions. With radar imaging, all foreslopes are shortened relatively to their true lengths (Fig. 1) . The degree of shortening is a function of the illumination geometry and the foreslope angle acording to the equation (1):
doi:10.1117/12.226823 fatcat:vfytanflibdvlcvxipfddmztfy