About this Research Topic
The ability of Synthetic Aperture Radar (SAR) to sense the Earth surface, even through dense cloud cover and in night-and-day condition, facilitated natural disasters management. More than twenty-five years of continuous SAR Earth observation since the start of the European Space Agency's C-band ERS-1 SAR satellite in 1991 resulted in numerous new insights of natural and man-made hazards. SAR data can be adopted to analyze a slow-moving surface in a variety of environments to understand their long-term behavior, which display episodic partial or total reactivations. This is of great interest for planning emergency responses over periods of critical meteo-hydro-geological conditions.
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 inclined with respect of Earth meridians. The most commonly used bands in SAR applications are: C-band (5–6 GHz, ~5,6 cm wavelength), X-band (8–12 GHz, ~3,1 cm wavelength) and L-band (1–2 GHz ~23 cm wavelength) with a temporal resolution depending on the satellite revisiting time. Space-borne active measurements from SAR have made a new spectrum of measurements possible on a global scale that can complement more focused ground-based studies and can also reveal insights into remote or poorly understood areas.
Mainly applications of SAR imagery are: i) quantifying topography; ii) tracking surface deformation, using the phase difference between two SAR images (Interferometric SAR, InSAR) or pixel offset in amplitude images; iii) mapping structures and deposits, using variation of the scattering properties of the surface. The use of InSAR, firstly developed for spaceborne application, has been extended to observations based on the use of airborne and ground-based microwave interferometer. Given their repeat time, ground-based SARs led the InSAR technique from monitoring to surveillance, becoming a common tool in landslides, volcanic and man-made (mines, dams, quarries) hazard early-warning applications.
The aim of this Research Topic is to give an updated overview of the progress in SAR application to hazard detection, mapping, monitoring, modelling and forecasting, from one sensor to multi-disciplinary efforts, from building to regional scale. Reviews and original contributions are welcome focusing on the application of SAR data to hazard mitigation, as:
- landslides and subsidence mapping, activity definition, and susceptibility assessment
- motion of volcanoes through the eruption cycle
- long-term tectonic ground motion and earthquake deformation
- mapping areas and buildings affected earthquakes, flooding, landslides and volcanic activity
- early-warning applications
- integration of SAR and derived products into operational monitoring and decision support systems
- man-made hazard monitoring (mine activity, dams stability, quarries, oil or water extraction)
Keywords: natural hazards, SAR, InSAR, SBAS, Landslides, Volcanoes, Earthquakes, Tectonics, GBInSAR
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.