Editorial: Synthetic Aperture Radar and Natural Hazards: Applications and Outlooks
Frontiers in Earth Science
Editorial on the Research Topic Synthetic Aperture Radar and Natural Hazards: Applications and Outlooks The ability of Synthetic Aperture Radar (SAR) to image the Earth's surface, even through dense cloud cover and in night-and-day conditions, can facilitate the evaluation and monitoring of natural hazards and the management of natural disasters. The family of SAR satellite sensors orbits the Earth at an altitude ranging from 500 to 800 km, following sun-synchronous, near-polar orbits, slightly
... ar orbits, slightly inclined with respect to Earth meridians. The most commonly used bands in SAR applications are the C-band (5-6 GHz, ∼5, 6 cm wavelength), the X-band (8-12 GHz, ∼3, 1 cm wavelength), and the L-band (1-2 GHz ∼23 cm wavelength) with a temporal resolution depending on the satellite revisiting time. The availability of SAR has made a new spectrum of measurements possible on a global and spatial scale not attainable by ground-based studies, revealing critical insights into remote or poorly understood areas (e.g., Biggs et al., 2014) . This Research Topics presents a review of articles on the state-of-art in the application of SAR sensors to study surface deformation in different geologic environments and triggered by a variety of processes. The topics discussed range from the analysis of co-seismic deformation ( Merryman Boncori) to studies of volcanic unrest (Dzurisin et al.; Garthwaite et al.), monitoring of landslides (Bianchini et al.) and ground subsidence in urban areas (Solari et al.). Merryman Boncori presents a review of the state-of-the-art concerning the co-seismic deformation measurement with space-borne SAR. SAR applications to over 100 case-studies since the launch of the SENTINEL-1A satellite are discussed, considering the performance of the different SAR sensors and data processing approaches. Although there has been a rapid spread of "free" software that allows DInSAR processing, there are only few systems able to carry out DInSAR processing of SENTINEL-1 data in an automated fashion. So, only few of the co-seismic deformation studies in the recent literature are based on automated processing chains. During the processing of a SAR data set, analysts must typically make several ad-hoc decisions, including what techniques to apply, which additional processing steps to include, and which approach to use for atmospheric corrections and phase unwrapping algorithms. All these issues are addressed in detail in this review.