The Daguangbao landslide (DGBL), the largest landslide triggered by the 2008 Ms 8.0 Wenchuan earthquake, has received much attention, but its long-term post-earthquake evolution and driving force of activity are still poorly understood. As the evolutionary behavior of the DGBL is complicated by the influence of mainshock, aftershocks and rainfall, it is of great significance to study the dynamics of the landslide. In this study, a systematic and comprehensive framework for assessing the long-term stability and risk of co-seismic landslides was proposed. Based on ALOS-1 and Sentinel-1 data, time-series InSAR technology was used to reveal the nearly 15-year post-seismic evolution characteristics of the DGBL at different stages, followed by the prediction of the stabilization time, the estimation of the landslide thickness and risk assessment. The first stage was identified as three years after the earthquake (2008–2011). During this stage, ALOS-1 results show that the deformation of DGBL was intense (300 mm/year) with uneven spatial distribution, and an aftershock (Ms 5.3), along with increased rainfall, triggered its acceleration in 2009. The second stage was the period from 2014 to 2022. For this stage, we used the mass conservation approach to invert the thickness of the DGBL, revealing that a new sliding surface and thickness center had formed following the co-seismic failure in 2008. Sentinel-1 time series results indicated that the DGBL remains active even 15 years after the Wenchuan earthquake, but the deformation of DGBL has significantly slowed down (50 mm/year). The stabilization time for different segments of DGBL was predicted to range from 2027 to 2040 according to an exponential model. Beyond the overall trend of recovery, seasonal movements (including localized acceleration in 2021) closely related to rainfall remained evident, but the impact of aftershocks on the DGBL was severely weakened over time. UAV and field survey results suggested that the risk of localized debris flows at DGBL still exists. Our study improves our understanding of the long-term evolutionary pattern of DGBL and provides an important reference for post-earthquake landslide risk assessment and disaster prevention.

中文翻译：

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通过 InSAR 观测描述 2008 年汶川地震近 15 年后大光堡滑坡的演变特征


大光堡滑坡 （DGBL） 是 2008 年汶川 8.0 级地震引发的最大滑坡，受到了广泛关注，但对其震后的长期演变和活动驱动力仍然知之甚少。由于DGBL的演化行为受主震、余震和降雨的影响而复杂，因此研究滑坡的动力学具有重要意义。本研究提出了一个系统、全面的框架，用于评估共震滑坡的长期稳定性和风险。基于ALOS-1和Sentinel-1数据，利用时间序列InSAR技术揭示了DGBL在不同阶段近15年的地震后演化特征，并预测了稳定时间、滑坡厚度估算和风险评估。第一阶段被确定为地震后三年（2008-2011 年）。ALOS-1 结果表明，2009 年DGBL 变形剧烈（300 mm/年），空间分布不均匀，余震（Ms 5.3）和降雨量增加触发了其加速。第二阶段是 2014 年至 2022 年期间。在这个阶段，我们使用质量守恒方法反转了 DGBL 的厚度，揭示了在 2008 年同震破坏后形成了一个新的滑动面和厚度中心。Sentinel-1 时间序列结果表明，即使在汶川地震发生 15 年后，DGBL 仍然活跃，但 DGBL 的变形明显减慢（50 mm/年）。根据指数模型，预计 DGBL 不同段的稳定时间在 2027 年至 2040 年之间。 除了总体恢复趋势外，与降雨密切相关的季节性变化（包括 2021 年的局部加速）仍然很明显，但余震对 DGBL 的影响随着时间的推移而严重减弱。无人机和现场调查结果表明，DGBL 局部泥石流的风险仍然存在。本研究提高了对 DGBL 长期演化模式的理解，为震后滑坡风险评估和灾害预防提供了重要参考。