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    基于多源遥感影像的西藏白格滑坡失稳前后全过程形变监测研究

    Whole-process deformation monitoring of the Baige landslide in Tibet before and after instability based on multisource remote sensing images

    • 摘要: 西藏白格滑坡于2018年10月和11月先后发生2次崩滑,造成了巨大的经济损失和广泛的社会影响。利用多源数据开展滑坡各阶段活动特征监测对理解此次滑坡事件的破坏机理具有重要意义。该文采用Sentinel-1,ALOS-2和Landsat8 3种数据源,通过短基线集合成孔径雷达干涉测量技术(small baseline subset interferometric synthetic aperture Radar,SBAS-InSAR)和SAR偏移量以及光学偏移量跟踪技术获取了白格滑坡滑前、2次滑动和滑后的形变特征。光学偏移量计算结果表明,白格滑坡在2014年11月—2018年3月29日的滑前阶段,累积位移量达到40 m,其形变区为滑坡中部。SAR偏移量结果也表明该滑坡在滑前2018年5月与7月的累积位移量达到了6.4 m,其形变区同样为滑坡中部。基于InSAR技术的监测结果揭示了白格滑坡2018年10月—11月2次失稳后,在滑坡后缘和滑坡左上侧仍存在明显的残余形变。白格滑坡在2018年11月—2021年11月滑后阶段,在滑坡的后缘高位处仍存在-140 mm/a的形变,且滑坡左上侧形变范围在持续扩大。该研究成果恢复了白格滑坡大量级位移的滑动全过程,为滑坡监测及预警研究提供了参考。

       

      Abstract: The Baige landslide occurred twice in October and November 2018, causing huge economic losses and extensive social impact. Monitoring the activity characteristics of the Baige landslide in various stages based on multisource data is significant for understanding the failure mechanism of this landslide. With Sentinel-1, ALOS-2, and Landsat8 data as data sources, this study derived the deformation characteristics of the Baige landslide before, during, and after two slide events using techniques, such as small baseline subset-interferometric synthetic aperture radar (SBAS-InSAR), SAR offset tracking, and optical offset tracking. The optical offset calculation results show that from November 2014 to March 29, 2018 in the pre-sliding stage, the cumulative displacement of the Baige landslide reached 40 m, with deformation concentrated in the middle of the landslide. The SAR offset results indicate that the cumulative displacement of the landslide reached 6.4 m in May and July 2018 in the pre-sliding stage, with deformation also concentrated in the middle of the landslide. The InSAR-based monitoring results reveal that after the two failures of the Baige landslide in October and November 2018, significant residual deformation remained in the trailing edge and upper left side of the landslide. From November 2018 to November 2021 in the post-sliding stage, the Baige landslide exhibited a deformation rate of -140 mm/y at the high trailing edge of the landslide, and the deformation range on the upper left side continued to expand. All the results of this study reconstructed the whole sliding process of the Baige landslide subjected to large displacements, providing a valuable reference for the monitoring and early warning of landslides.

       

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