The most important reason to use radar instead of optical sensors is its capability to penetrate through clouds and its day and night imaging capabilities. However, radar interferometry might add yet another reason to use radar. Recently it has been shown, that with spaceborne Synthetic Aperture Radar, deformations of the surface of the Earth can be measured with sub-centimetre accuracy. This information becomes available by using interferometric processing techniques of multiple satellite images from the satellite. In this article the basics of the technique and its potential as well as the limitations are outlined. -from Authors@en