Inventory of Ring Structures in N- and W-Morocco based on Satellite Data

Abstract

This study is focused on the detection of circular features with different sizes, origins, and state of erosion as well as on their surrounding tectonic pattern based on satellite images of North- and West- Morocco. Sentinel 2- and Landsat 8/9-images and Sentinel 1 radar data help to identify larger ring structures and smaller circular features. Digital Elevation Model (DEM) data and the DEM derived morphometric maps support these investigations in a GeoInformation System (GIS) embedded environment. The evaluations of the various satellite data, especially after digital image processing of the thermal bands, contribute to the inventory larger ring structures with diameters of 10 km up to more than 50 km related to magmatic intrusions or to salt domes in the subsurface with varying grades of erosion. Some of these larger ring structures are only visible on morphometric maps, traced by circular arrangements of slope gradients or a concentric drainage pattern. Smaller circular features such as volcanic features (cinder cones, calderas, maars), and sinkholes in karst environments with diameters ranging from several 10 m up to more than 500 m were digitized as well. As karst phenomena, volcanic features or halotectonic movements may cause damage to the infrastructure the inventory of ring structures should be part of a natural hazard GIS.