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

S. Salvi, S. Stramondo, G.J. Funning, A. Ferretti, F. Sarti, A. Mouratidis
2012 Remote Sensing of Environment  
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
more » ... ed so far the operational use of satellite data in seismic hazard assessment and crisis management, and show the improvements expected from Sentinel-1 data. j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / r s e for the operational crisis management and mitigation. We shall evidence the new possibilities provided by the Sentinel-1 platform and sensor characteristics, for the improvements of these applications and for establishing new ones. Using synthetic aperture radar interferometry (InSAR) to measure surface deformation In this section we briefly introduce the SAR processing techniques used in geophysical applications; for a more detailed treatment of the subject we refer the reader to A SAR image contains a two-dimensional record of both the amplitude and the phase of the returns from targets within the imaging area. The amplitude stands for the reflectivity while the phase is a term proportional to the sensor-to-target distance. A particular SAR data processing technique referred to as InSAR (Interferometric SAR) is widely used in seismology, volcanology, hydrogeology, glaciology and subsidence studies. The InSAR approach aims at estimating any variation of the phase component of two or more SAR images taken under the same acquisition geometry. This means that the images need to be acquired along the same orbit, at different times (repeat-pass configuration). Since SAR is a coherent sensor, the phase information of any SAR image is related to the sensor-to-target distance. The interferogram, i.e. the result of the interferometric processing, is generated by computing the phase difference of two radar images on a pixel-by-pixel basis. Indeed, satellite SAR sensors can acquire new data over the same area of interest, using the same acquisition geometry, many times a year, thus allowing a comparison of the phase maps at different times. In repeat-pass interferometry, the temporal baseline is the time difference between two SAR acquisitions, the minimum temporal baseline corresponds to the satellite "repeat-cycle" (or revisit time) and varies from 11 days to 46 days for the satellites available today. Using satellite constellations, the actual revisit time can be further reduced to only few days.
doi:10.1016/j.rse.2011.09.029 fatcat:fzultjqb2jhwpjaf4v5q52nxy4