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Monitoring activity at the Daguangbao mega-landslide (China) using Sentinel-1 TOPS time series interferometry

Lookup NU author(s): Professor Zhenhong Li, Dr Roberto Tomas-Jover, Jiajun Chen, Julia Stockamp



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


The Daguangbao mega-landslide (China), induced by the 2008 Wenchuan earthquake (Mw=7.9), with an area of approximately 8 km2, is one of the largest landslides in the world. Experts predicted that the potential risk and instability of the landslide might remain for many decades, or even longer. Monitoring the activity of such a large landslide is hence critical. Terrain Observation by Progressive Scans (TOPS) mode from the Sentinel-1 satellite provides us with up-to-date high-quality Synthetic Aperture Radar (SAR) images over a wide ground coverage (250 x 250 km), enabling full exploitation of various InSAR applications. However, the TOPS mode introduces azimuth-dependent Doppler variations to radar signals, which requires an additional processing step especially for SAR interferometry. Sentinel-1 TOPS data has been widely applied to earthquakes, but the performance of TOPS data-based time series analysis requires further exploitation. In this study, Sentinel-1 TOPS data was employed to investigate landslide post-seismic activities for the first time. To deal with the azimuth-dependent Doppler variations, a processing chain of TOPS time series interferometry approach is developed. Since the Daguangbao landslide is as a result of the collapse of a whole mountain caused by the 2008 Mw 7.9 Wenchuan earthquake, the existing Digital Elevation Models (DEMs, e.g. SRTM and ASTER) exhibit height differences of up to approximately 500 m. Tandem-X images acquired after the earthquake were used to generate a high resolution post-seismic DEM. The high gradient topographic errors of the SRTM DEM (i.e. the differences between the pre-seismic SRTM and the actual post-seismic elevation), together with low coherence in mountainous areas make it difficult to derive a precise DEM using the traditional InSAR processing procedure. A re-flattening iterative method was hence developed to generate a precise TanDEM-X DEM in this study. The volume of the coseismic Daguangbao landslide was estimated to be of 1.189±0.110 x 109 m3 by comparing the postseismic Tandem-X DEM with the preseismic SRTM DEM, which is consistent with the engineering geological survey result. The time-series results from Sentinel-1 show that some sectors of the Daguangbao landslide are still active (and displaying four sliding zones) and exhibiting a maximum displacement rate of 8 cm/year, even eight years after the Wenchuan earthquake. The good performance of TOPS in this time series analysis indicates that up-to-date high-quality TOPS data with spatiotemporal baselines offer significant potential in terms of future InSAR applications.

Publication metadata

Author(s): Dai K, Li Z, Tomás R, Liu G, Yu B, Wang X, Cheng H, Chen J, Stockamp J

Publication type: Article

Publication status: Published

Journal: Remote Sensing of Environment

Year: 2016

Volume: 186

Pages: 501-513

Print publication date: 01/12/2016

Online publication date: 24/09/2016

Acceptance date: 14/09/2016

Date deposited: 14/09/2016

ISSN (print): 0034-4257

ISSN (electronic): 1879-0704

Publisher: Elsevier


DOI: 10.1016/j.rse.2016.09.009


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Funder referenceFunder name
NE/K010794/1Natural Environment Research Council (NERC)
NE/N012151/1Natural Environment Research Council (NERC)