资源环境科技发展态势分析平台

Anthropogenic changes to the environment can enhance earthquake-triggered landslides, yet their role in earthquake disasters is often overlooked. Co-seismic landslides frequently involve liquefaction of granular materials, a process that reduces shear strength and facilitates downslope motion even on gentle slopes. Irrigation systems can increase liquefaction susceptibility and compromise otherwise stable slopes. Here we investigate devastating landslides that affected Palu, Indonesia, during the 28 September 2018 earthquake of moment magnitude 7.5. We document fields and buildings translated over 1 km down slopes of <2 degrees and show that landslides were limited to irrigated ground. A liquefied detachment was rooted upslope in a conveyance canal that supplied water to the irrigation network. A strong correlation between landslide displacement, irrigation infrastructure and the highest slopes (>= 1.5 degrees) suggests a causative mechanism that should provoke urgent assessment of gently sloping irrigated terrain elsewhere in Sulawesi and in tectonically active areas worldwide.