Monitoring Strategy of Geological Hazards Using Integrated Three-dimensional InSAR and GNSS Technologies with Case Study

Abstract

Geodetic/geodynamic benchmarks, equipped with both ascending and descending radar corner reflectors, and a method for integrated InSAR and GNSS/GPS network observation were developed and applied as the continuation of the former geodetic monitoring at the Dunaszekcső landslide, Hungary. The attempts to apply InSAR technologies using archive and Sentinel-1 data practically failed on the most intensive landside areas (“Vár” and “Szent János” hills), where proper persistent or distributed scatterers were not found. Our concept solved this problem, where the Simple Look Complex (SLC) images are used to interpolate the movements between two GNSS network observations using the integrated benchmarks and the method of Kalman-filtering. Since the InSAR line-of-sight (LOS) changes are barely sensitive to the north movements, this information is essentially provided by GNSS measurement alone, moreover, the GNSS measurements are used to: a) identify the benchmarks, b) detect the unwrapping errors and missing cycles and c) provide the boundary values of Kalman-filtering.After the installation of benchmarks three GPS observations were carried out and 69 ascending and 61 descending Sentinel-1 A and B images were processed. The data processing properly indicated the general movement history, which fit the curves of former geodetic observations, as well. The dense data points of the East and Up (vertical) components made possible more detailed geomorphologic interpretations of the ongoing process between two GPS observations. During the investigated periods the deceleration of movements was experienced, however, the deceleration of the dormant state needs the continuation of the monitoring.