Li Gen K, West A Joshua, Jin Zhangdong, Qiu Hongrui, Zhang Fei, Wang Jin, Hammond Douglas E, Densmore Alexander L, Hilton Robert G, Dong Sijia, Atwood Abra, Fischer Woodward W, Lamb Michael P
Department of Earth Science, University of California, Santa Barbara, CA, USA.
Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA.
Nature. 2025 Aug;644(8076):398-403. doi: 10.1038/s41586-025-09354-8. Epub 2025 Aug 13.
Large earthquakes induce widespread landslides that fill river channels with sediment, generating long-lasting fluvial hazards and reshaping mountain topography. However, riverine sediment fluxes after earthquakes remain poorly resolved, mostly because of a lack of data on bedload flux. Here we construct a source-to-sink sediment budget following the 2008 M7.9 (where M is the moment magnitude) Wenchuan earthquake in the eastern Tibetan mountains. We measured sediment accumulation in a man-made reservoir downstream of the earthquake-affected region. Ten years after the earthquake, the Min Jiang River had exported about 9% of the sediment mass from earthquake-triggered landslides, with around 5.7 times increase in the total riverine sediment flux sustained over that time. Bedload flux increased by times compared with pre-earthquake levels, making up of the post-earthquake sediment export-a proportion much higher than typical of most mountainous rivers. At the current pace, the river system will remove most Wenchuan landslide debris over centennial timescales. However, future sediment export rates are likely to vary because of changes on hillslopes (for example, revegetation) and in hydrology, sediment characteristics and transport processes. Our findings demonstrate a decadal bedload-dominated sediment pulse driven by earthquake-triggered landslides, suggesting that increased vulnerability to cascading hazards such as aggradation and flooding could persist for decades in populated downstream regions after a large earthquake.
大地震会引发大面积山体滑坡，滑坡产生的沉积物会填满河道，造成长期的河流灾害，并重塑山地地形。然而，地震后的河流泥沙通量仍难以确定，主要原因是缺乏推移质通量数据。在此，我们构建了2008年发生在青藏高原东部的里氏7.9级（M为矩震级）汶川地震后的源汇泥沙收支情况。我们测量了地震影响区域下游一座人工水库中的泥沙淤积情况。地震十年后，岷江已输出了地震引发山体滑坡产生泥沙总量的约9%，在此期间河流总泥沙通量持续增加了约5.7倍。与震前水平相比，推移质通量增加了 倍，占地震后泥沙输出量的 ，这一比例远高于大多数山区河流的典型比例。按照目前的速度，河流系统将在百年时间尺度上清除大部分汶川滑坡的碎屑。然而，由于山坡（如植被恢复）、水文、泥沙特性和输运过程的变化，未来的泥沙输出率可能会有所不同。我们的研究结果表明，地震引发的山体滑坡会导致以推移质为主导的十年尺度泥沙脉冲，这表明大地震后，下游人口密集地区对诸如淤积和洪水等连锁灾害的脆弱性增加可能会持续数十年。
