The role of GNSS monitoring in landslide research

GNSS is a useful technique to monitor and study the deformation dynamics of landslides. The technique is best suited for slow-to-intermediate moving landslides with temporally varying movements, such as rotational or translational landslides, however, can also be used for stability monitoring of other landslide types. Installing and operating GNSS instruments can be challenging in unstable slopes and harsh weather conditions. Several landslides around the world have GNSS instruments dedicated to monitoring and researching the landslide motion. The types of instruments vary considerably, from CORS-grade equipment to single-frequency code-only instruments, where large motion can be expected. A common trigger for accelerated landslide motion is heavy precipitation, however, earthquakes and other processes can also trigger motion. The strength of the GNSS technique for landslide monitoring lies in its ability to give low-latency, high-precision 3D deformation results with the possibility of high temporal resolution. Furthermore, the detailed long-term time series resulting from GNSS measurements are important to understand better the dynamics of landslide deformation.