Earthquake-triggered 2018 Palu Valley landslides enabled by wet rice cultivation
Earthquake-triggered 2018 Palu Valley landslides enabled by wet rice cultivation
复制标题
DOI：
10.1038/s41561-019-0444-1
复制
发表时间：
2019-11-01
影响因子：
18.3
通讯作者：
Hill, Emma M.
中科院分区：
文献类型：
--
作者：
Bradley, Kyle;Mallick, Rishav;Hill, Emma M.
如果地震引起的地面震动引发山体滑坡，地震的死亡人数和经济影响可能会大大加剧。地震引发的山体滑坡通常发生在两种不同的情况下：陡坡的局部破坏和由此产生的山体滑坡，对下面地区的生命构成重大威胁;由于震动引起的液化，几乎平坦的沉积平原横向扩展，这可能会破坏大面积的关键基础设施。2018年9月28日印度尼西亚帕卢地震引发的意外灾难性滑坡并没有发生在这两种典型的情况下，但却产生了两种破坏性的结果。在这里，我们表明，冲积地面故障在帕卢山谷灌溉造成新的液化危险的直接后果。水渠支持的种植，主要是湿稻，提高了地下水位接近地面水平，饱和桑迪冲积土，液化反应强烈的地面震动。大位移横向扩展发生在1度的斜坡上。坡度超过1.5度的斜坡会引发长时间的山体滑坡和泥石流，这些泥石流会席卷下方坡度较缓的村庄。如果没有地下水位上升，可能不会发生由此造成的损害和生命损失。地震引发的滑坡平缓，灌溉冲积坡是一个认识不足，但可以避免的人为灾害。
The death toll and economic impact of an earthquake can be greatly exacerbated if seismic ground shaking triggers landslides. Earthquake-triggered landslides typically occur in two different contexts: localized failure of steep slopes and resulting landslides that pose a major threat to life in areas below; and lateral spreading of nearly flat sediment plains due to shaking-induced liquefaction, which can damage large areas of critical infrastructure. Unexpected catastrophic landsliding triggered by the 28 September 2018 earthquake at Palu, Indonesia did not occur in either typical context, but produced both destructive outcomes. Here, we show that alluvial ground failure in the Palu Valley was a direct consequence of irrigation creating a new liquefaction hazard. Aqueduct-supported cultivation, primarily of wet rice, raised the water table to near ground level, saturating sandy alluvial soils that liquefied in response to strong ground shaking. Large-displacement lateral spreads occurred on slopes of 1 degrees. Slopes steeper than 1.5 degrees sourced long-runout landslides and debris flows that swept through villages occupying the gentler slopes below. The resulting damage and loss of life would probably not have occurred in the absence of a raised water table. Earthquake-triggered landsliding of gentle, irrigated alluvial slopes is an under-recognized, but avoidable, anthropogenic hazard.