Landslide mobility and hazards: implications of the 2014 Oso disaster
Landslide mobility and hazards: implications of the 2014 Oso disaster
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DOI：
10.1016/j.epsl.2014.12.020
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发表时间：
2015-02
影响因子：
5.3
通讯作者：
R. M. Iverson;D. George;K. Allstadt;M. Reid;B. Collins;J. Vallance;S. Schilling;J. Godt;C. Cannon;C. Magirl;R. Baum;J. Coe;W. Schulz;J. Bower
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作者：
R. M. Iverson;D. George;K. Allstadt;M. Reid;B. Collins;J. Vallance;S. Schilling;J. Godt;C. Cannon;C. Magirl;R. Baum;J. Coe;W. Schulz;J. Bower
滑坡反映了在气象和地质时间尺度上演变的景观不稳定性，它们也对人，财产和环境构成威胁。这些威胁的严重程度在很大程度上取决于滑坡的速度和移动距离，统称为滑坡的“流动性”。为了调查流动性的原因和影响，我们专注于2014年3月22日发生在美国华盛顿奥索附近的灾难性山体滑坡，经过长时间的异常潮湿天气。滑坡的影响是严重的，因为它的流动性超过了该地点以前的历史滑坡，也超过了其他地方的可比滑坡。该滑坡发生在一个仅180 m高的缓坡（< 20°）滨江陡崖上，其宽度约为10.1 km，横向扩展距离约为10.1 km。地震学证据表明，高速，流动运动的滑坡开始后约50秒的初步斜坡运动，和观测证据支持的假设，即高流动性的滑坡是由于液化的水饱和沉积物在其基础上。使用新开发的模型的事件的数值模拟表明，液化和高流动性可以归因于压缩和/或剪切引起的沉积物收缩，强烈依赖于初始条件。另一种数值模拟表明，如果滑坡的初始孔隙度和含水量仅略低，滑坡的移动的会小得多。滑坡活动性对初始条件的敏感依赖性对滑坡灾害的评估具有广泛的意义。
Landslides reflect landscape instability that evolves over meteorological and geological timescales, and they also pose threats to people, property, and the environment. The severity of these threats depends largely on landslide speed and travel distance, which are collectively described as landslide “mobility”. To investigate causes and effects of mobility, we focus on a disastrous landslide that occurred on 22 March 2014 near Oso, Washington, USA, following a long period of abnormally wet weather. The landslide's impacts were severe because its mobility exceeded that of prior historical landslides at the site, and also exceeded that of comparable landslides elsewhere. The∼ 8× 10 6 m 3 landslide originated on a gently sloping (< 20°) riverside bluff only 180 m high, yet it traveled across the entire∼ 1 km breadth of the adjacent floodplain and spread laterally a similar distance. Seismological evidence indicates that high-speed, flowing motion of the landslide began after about 50 s of preliminary slope movement, and observational evidence supports the hypothesis that the high mobility of the landslide resulted from liquefaction of water-saturated sediment at its base. Numerical simulation of the event using a newly developed model indicates that liquefaction and high mobility can be attributed to compression-and/or shear-induced sediment contraction that was strongly dependent on initial conditions. An alternative numerical simulation indicates that the landslide would have been far less mobile if its initial porosity and water content had been only slightly lower. Sensitive dependence of landslide mobility on initial conditions has broad implications for assessment of landslide hazards.