Richat Structure, LiDAR satellite image. The Richat Structure is an eroded volcanic dome in the deserts of Mauritania. As the volcanic dome eroded, concentric layers of rock were exposed. The structure is 485 metres high, and nearly 50 kilometres across. It is in the Maur Adrar Desert, in the Western Sahara. LiDAR combines optical and laser imaging to produce digital elevation maps (DEMs), with differences in elevation shown by the colour-coding of the image. Image data obtained by the radar and optical sensors on the Advanced Land Observation Satellite (ALOS) of the Japan Aerospace Exploration Agency (JAXA).