The Sentinel-1 mission for the improvement of the scientific understanding and the operational monitoring of the seismic cycle

a r t i c l e i n f o We describe the state of the art of scientific research on the earthquake cycle based on the analysis of Synthetic Aperture Radar (SAR) data acquired from satellite platforms. We examine the achievements and the main limitations of present SAR systems for the measurement and analysis of crustal deformation, and envision the foreseeable advances that the Sentinel-1 data will generate in the fields of geophysics and tectonics. We also review the technological and scientific issues which have limited so far the operational use of satellite data in seismic hazard assessment and crisis management, and show the improvements expected from Sentinel-1 data. Earthquakes and fault ruptures cannot be directly observed at the depths at which they originate. This, and the fact that earthquake processes span several orders of magnitude of space and time scales, complicates the scientific understanding of these phenomena (Rundle et al., 2003). Seismology is in fact a science largely based on observations not only of present events, but also of those registered in the historical and geological records. During the last couple of decades, our understanding of earthquake and fault processes has improved, thanks to new observational methods, as broadband seismology, Global Positioning System (GPS) and SAR Interferometry (InSAR). Development of new observation tools and datasets has always led in short order to scientific advancements. For example, plate tectonics, the most revolutionary Earth science theory of the past century, could only be fully developed when new, improved, and systematic observations of the Earth's gravity and magnetic fields, precise locations of global earthquakes and detailed measurements of seafloor bathymetry, started to become available in the 1950s and 1960s. Today the Solid Earth scientist has the technological means to generate a wealth of spatially and temporally denser observations to constrain better earthquake models and improve the understanding of the fundamental physical processes driving the earthquake cycle. What is really needed is to make these observations systematic and constant over a long period of time. Measurement instruments placed on satellite platforms are among the best ways to provide systematic observation of the Earth surface over large areas and over long time intervals. In the field of geophysics the most successful of such instruments in the last two decades has been the Synthetic Aperture Radar (SAR). Using SAR images of the ground acquired at different times, an accurate , quantitative measurement of …