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<p>Giant landslides seldom result from a single storm or earthquake. They more often reflect long-term conditioning that weakens a slope, followed by a brief disturbance that delivers the final push. The Xiaqiongsi (XQS) landslide in the upper Yellow River illustrates this sequence. An integrated approach combining geomorphological mapping, P-wave refraction tomography, borehole control, optically stimulated luminescence (OSL) dating, limit-equilibrium analysis (static scenarios), and Newmark sliding block analysis (dynamic scenarios) was used to reconstruct the pre-failure slope and to assess the relative roles of climate and earthquakes. Failure occurred along a basal shear zone at 35 to 40&#xa0;m depth in water-sensitive Neogene red-bed mudstone; the landslide mobilized about 2.39 × 10<sup>8</sup> m<sup>3</sup> and traveled approximately 2.3&#xa0;km. The onset of lacustrine infill yields an OSL age of 13.1 ± 0.7&#xa0;ka, placing failure within a late-deglacial warming and humidification phase. In static limit-equilibrium analysis, assigning near-saturated pore pressures along the basal shear zone and using residual shear strength gives a factor of safety (FOS) = 1.453, indicating that rainfall alone is unlikely to reactivate sliding on the existing surface. Newmark sliding-block calculations show that, in the natural, unsaturated state of the basal shear zone, the critical peak ground acceleration (PGA) for reactivation is ≥ 0.66&#xa0;g. When the basal shear zone is saturated and strength degraded, the critical PGA drops to 0.27 to 0.35&#xa0;g, compatible with <i>M</i><sub>w</sub> 6.1 to 6.3 earthquakes on the Laji–Jishi Shan Fault system (LJSFS). These results support a coupled mechanism: centennial–millennial humidification drives mass rock creep (MRC), elevates pore-water pressure, and weakens the basal shear zone; once near critical conditions, seismic shaking provides the proximal trigger. This climate-preconditioning–seismic-triggering sequence is likely recurrent in deeply incised, mudstone-dominated basins and should inform hazard assessments that jointly consider hydrologic state, creep indicators, and credible seismic scenarios.</p>

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Climatic preconditioning and seismic triggering of the Xiaqiongsi giant landslide, upper Yellow River

  • 期刊论文

  • 发表日期：

    2025年11月4日

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  • Jiale Zhang,
  • Weiliang Huang,
  • Yu Li,
  • Zhimin Li,
  • Song Wang,
  • Fatima Zahra,
  • Qiangbin Huang,
  • Jianbing Peng

摘要

Giant landslides seldom result from a single storm or earthquake. They more often reflect long-term conditioning that weakens a slope, followed by a brief disturbance that delivers the final push. The Xiaqiongsi (XQS) landslide in the upper Yellow River illustrates this sequence. An integrated approach combining geomorphological mapping, P-wave refraction tomography, borehole control, optically stimulated luminescence (OSL) dating, limit-equilibrium analysis (static scenarios), and Newmark sliding block analysis (dynamic scenarios) was used to reconstruct the pre-failure slope and to assess the relative roles of climate and earthquakes. Failure occurred along a basal shear zone at 35 to 40 m depth in water-sensitive Neogene red-bed mudstone; the landslide mobilized about 2.39 × 108 m3 and traveled approximately 2.3 km. The onset of lacustrine infill yields an OSL age of 13.1 ± 0.7 ka, placing failure within a late-deglacial warming and humidification phase. In static limit-equilibrium analysis, assigning near-saturated pore pressures along the basal shear zone and using residual shear strength gives a factor of safety (FOS) = 1.453, indicating that rainfall alone is unlikely to reactivate sliding on the existing surface. Newmark sliding-block calculations show that, in the natural, unsaturated state of the basal shear zone, the critical peak ground acceleration (PGA) for reactivation is ≥ 0.66 g. When the basal shear zone is saturated and strength degraded, the critical PGA drops to 0.27 to 0.35 g, compatible with Mw 6.1 to 6.3 earthquakes on the Laji–Jishi Shan Fault system (LJSFS). These results support a coupled mechanism: centennial–millennial humidification drives mass rock creep (MRC), elevates pore-water pressure, and weakens the basal shear zone; once near critical conditions, seismic shaking provides the proximal trigger. This climate-preconditioning–seismic-triggering sequence is likely recurrent in deeply incised, mudstone-dominated basins and should inform hazard assessments that jointly consider hydrologic state, creep indicators, and credible seismic scenarios.