Abstract
Monitoring slope instability is of great significance for understanding landslide kinematics and, therefore, reducing the related geological hazards. In recent years, interferometric synthetic aperture radar (InSAR) has been widely applied to this end, especially thanks to the prompt evolution of multi-temporal InSAR (MTInSAR) algorithms. In this paper, temporarily-coherent point InSAR (TCPInSAR), a recently-developed MTInSAR technique, is employed to investigate the slow-moving landslides in Oso, U.S., with 13 ALOS/PALSAR images. Compared to other MTInSAR techniques, TCPInSAR can work well with a small amount of data and is immune to unwrapping errors. Furthermore, the severe orbital ramps emanated from the inaccurate determination of the ALOS satellite’s state vector can be jointly estimated by TCPInSAR, resulting in an exhaustive separation between the orbital errors and displacement signals. The TCPInSAR-derived deformation map indicates that the riverside slopes adjacent to the North Fork of the Stillaguamish River, where the 2014 mudslide occurred, were active during 2007 and 2011. Besides, Coal Mountain has been found to be experiencing slow-moving landslides with clear boundaries and considerable magnitudes. The Deer Creek River is also threatened by a potential landslide dam due to the creeps detected in a nearby slope. The slope instability information revealed in this study is helpful to deal with the landslide hazards in Oso.
Highlights
As one of the most frequently occurring natural hazards, landslides pose great threats to public safety in the world
It is clear that these two kinds of phase variations are visually similar and quite difficult to distinguish based on one single differential InSAR (DInSAR) image
interferometric synthetic aperture radar (InSAR) has been proven to be a powerful tool for monitoring slow-moving landslides, this is not an easy task, since the inherent InSAR errors, such as decorrelation noise and topographic residuals, become more troublesome in the areas where landslide hazards frequently occur, which are usually dominated by mountains and hills with steep slopes
Summary
As one of the most frequently occurring natural hazards, landslides pose great threats to public safety in the world. As an imaging radar system, InSAR is independent of sunlight and weather and can provide spatially-dense ground deformation measurements at a relatively large scale, without the need to carry out an in situ survey [3,4] These characteristics are of great importance for monitoring those landslides in mountainous areas, where there is a lack of public concern. By exploiting time series SAR images acquired over the same area during a certain period, these MTInSAR techniques can overcome the limitations associated with DInSAR and, improve the deformation measurement accuracy, as well as generate the deformation time series These advancements have made MTInSAR widely employed for landslide investigation [13,14,15,16,17,18].
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