Investigating slow-moving landslides in the Zhouqu region of China using InSAR time series

Abstract

In the Zhouqu region (Gansu, China), landslide distribution and activity exploits geological weaknesses in the faultcontrolled belt of low-grade metamorphic rocks of the Bailong valley and severely impacts lives and livelihoods in this region. Landslides reactivated by the Wenchuan 2008 earthquake and debris flows triggered by rainfall, such as the 2010 Zhouqu debris flow, have caused more than 1700 casualties and estimated economic losses of some US$0.4 billion. Earthflows presently cover some 79% of the total landslide area and have exerted a strong influence on landscape dynamics and evolution in this region. In this study, we use multi-temporal Advanced Land Observing Satellite and Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR) data and time series interferometric synthetic aperture radar to investigate slow-moving landslides in a mountainous region with steep topography for the period December 2007-August 2010 using the Small Baseline Subsets (SBAS) technique. This enabled the identification of 11 active earthflows, 19 active landslides with deformation rates exceeding 100 mm/year and 20 new instabilities added into the pre-existing landslide inventory map. The activity of these earthflows and landslides exhibits seasonal variations and accelerated deformation following the Wenchuan earthquake. Time series analysis of the Suoertou earthflow reveals that seasonal velocity changes are characterized by comparatively rapid acceleration and gradual deceleration with distinct kinematic zones with different mean velocities, although velocity changes appear to occur synchronously along the landslide body over seasonal timescales. The observations suggest that the post-seismic effects (acceleration period) on landslide deformation last some 6-7 months.

Experimental study of loess disintegration characteristics

“…The Loess Plateau also experiences some of the highest soil erosion and geologic hazard in the world (Zhang et al, 2018). The Loess Plateau is high in the northwest and low in the southeast, and undulates down from the northwest to the southeast.…”

“…The rainy season of the loess plateau is mainly in summer and autumn, while precipitation in winter and spring is characterized by drought and little rain, with annual precipitation ranging from 150 to 750 mm. The Loess Plateau also experiences some of the highest soil erosion and geologic hazard in the world (Zhang et al, 2018). The Shaanxi, Shanxi, and Gansu provinces and the Ningxia Hui Autonomous Region are the main Chinese administrative districts of the Loess Plateau.…”

Landslide-Induced Damage Probability Estimation Coupling InSAR and Field Survey Data by Fragility Curves

“…To partially solve the underestimation related to LOS velocities, we reconstructed with good approximation the real component along the maximum slope using the Vslope method. This approach, used by many authors for landslide monitoring, can be supported and validated by in situ measurements, if available e.g., [83][84][85][86].…”

Integrated Procedure for Monitoring and Assessment of Linear Infrastructures Safety (I-Pro MONALISA) Affected by Slope Instability

“…In recent years, remote sensing methodologies for Earth observation have gained more and more attention and appreciation, also consolidated by good results, so far achieved as tools for the monitoring of a wide range of deformation phenomena occurring on Earth's surface [7][8][9][10][11][12][13][14][15][16][17]. Remote sensing tools, indeed, have become rapidly one of the most important and valuable methods for the prevention and investigation of instabilities, thanks to their rapidity of acquisition, the easy management of the data and for the relative low costs as well.…”