Image of the Merapi volcano acquired by TanDEM-X

German radar technology for crisis management – the Earth observation satellite TanDEM-X acquired this image of the Indonesian volcano Mount Merapi shortly before it erupted. Hundreds of thousands of people live in the direct vicinity of this volcano and in the city of Yogyakarta, located to the south. When such volcanoes are active and further eruptions appear imminent, it is vitally important to be able to make fast and accurate predictions about the possible courses of new lava flows with the help of three-dimensional Digital Elevation Models (DEM), so that people can be warned and evacuated to safety. Lower resolution digital elevation models do not provide the requisite level of detail about mountain slopes, and gullies and small river courses do not show up on older terrain models. Germany's unique TanDEM-X mission is mapping the entire surface of Earth several times over a period of three years – in three dimensions.