Natural hazard monitoring with global navigation satellite systems (GNSS)

For more than three decades, Global Navigation Satellite Systems (GNSS) have been essential sensors for monitoring ground deformations and the state of the atmosphere. Geodetic GNSS is crucial for resolving spatial and temporal characteristics of geophysical processes, capturing variations that range from decades to sub-seconds, and from local to global scales. Applications include fields such as geodynamics, seismology, andmeteorology. GNSS can detect long-term changes at the sub-millimeter-per-year level and rapid movements with sub-centimeter precision, making them essential for monitoring plate tectonics, earthquakes, atmospheric water vapor, and ionospheric disturbances. Consequently, GNSS are important for detecting and understanding natural hazards such as earthquakes, landslides, or severe weather events. This review introduces and examines the role of ground-based GNSS in monitoring natural hazards. It highlights key developments and applications in geodetic GNSS for geological and lithospheric hazards (earthquakes, landslides, volcanoes), tropospheric hazards (severe weather), and ionospheric disturbances from natural hazards and space weather events. The review discusses advancements and limitations of GNSS for geophysical applications, its integration with other sensors (e.g., seismometers, InSAR), and recent developments in low-cost GNSS technology and machine learning for hazard monitoring. Additionally, it covers GNSS radio occultation (GNSS-RO) for atmospheric monitoring and provides an overview of open-source GNSS software, key data providers, and online portals.