Storm-triggered landslides² cause loss of life, property damage, and landscape alterations³. For instance, the remnants（残余） of Hurricane Camille in 1969 caused 109 deaths in central Virginia, after 600 mm of rain fell in mountainous terrain⁴ in 6 hours. More recently, on 8 August 2010, a rainstorm-induced landslide¹ devastated⁵ the Chinese county of Zhouqu, causing more than 1000 deaths. A new modeling study by Ren examines the multiple factors, both natural and human caused, that came together to produce this event. The triad（三个一组） of storm-triggered landslides is geological condition, surface loading and vegetation roots, and extreme precipitation（降水，沉淀）. Extreme precipitation can be explained by three factors: low-level moisture buildup, conditional⁶ instability, and a lifting mechanism⁷. When several factors (e.g., El Niño years, hurricane remnants, lifting mechanisms⁸ (e.g., orography, cold fronts, jets, and differential heating from land cover contrast), and weather pattern phase-lock) work in synergy in a region, extreme precipitation may occur.

 

Using a multiple-phase scalable and extensible geofluid model, the author considered geological features of the region, as well as an earthquake, drought, deforestation, and topsoil（表层土） erosion before the triggering storm. Previously⁹, drought conditions created cracks and crevices¹⁰ in the surface; these cracks and crevices were deepened by the 2008 M7.9 Wenchuan earthquake.

 

Another key factor in setting up the conditions for the landslide was human-induced deforestation and topsoil erosion, the study found. The results "underscore the urgency for a high priority program of re-vegetation of Zhouqu County, without which the region will remain exposed to future disastrous¹¹, progressive bulking type landslides," the author reports.

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