Two Radar Interferometric Approaches to Monitor Slow and Fast Land Deformation

Differential interferometric synthetic aperture radar (DInSAR) is a deformation measurement technique that couples two interesting characteristics. First, being based on remotely sensed data it offers operational advantages, like low cost data acquisition, wide area coverage, and temporally regular acquisitions. Second, it can be based on rigorous modeling and estimation procedures, which allows some of the most advanced techniques to derive measurements with high quality standards, comparable with those of some geodetic methods. The scope of this paper is to describe two complementary approaches to measure slow (from a few millimeters up to some centimeters per year) and fast land deformation (up to few meters per year). Emphasis is given to the description of the former approach, which requires multiple SAR images of the same phenomenon and an advanced analysis procedure. The effectiveness of both approaches is illustrated through two applications on mining areas of small spatial extent located in Spain. In one case the DInSAR capability to fully detect shape and magnitude of an unknown fast deformation phenomenon is highlighted, whereas in the second one a detailed deformation map is derived over an urban area, where deformations up to $30\mathrm{mm}∕\mathrm{year}$ occur.