Abstract. In 2018, Typhoon Mangkhut (locally known as Typhoon Ompong) triggered thousands of landslides in the area of Itogon (Philippines). A landslide inventory of 1101 landslides over a 570 km² area is used to study the geomorphological characteristics and land cover more prone to landsliding as well as the rainfall and soil moisture conditions that led to widespread failure. Landslides mostly occurred in slopes covered by wooded grassland in clayey materials, predominantly facing East–Southeast. The analysis of both satellite rainfall (GPM IMERG) and soil moisture (SMAP-L4) finds that, in addition to rainfall from the typhoon, soil water content plays an important role in the triggering mechanism. Rainfall associated with Typhoon Mangkhut is compared with 33 high intensity rainfall events that did not trigger regional landslide events in 2018 and with previously published rainfall thresholds. Results show that: (a) it was one of the most intense rainfall events in the year but not the highest, and (b) despite satellite data tending to underestimate intense rainfall, previous published regional and global thresholds are to be too low to discriminate between landslide triggering and non-triggering rainfall events. This work highlights the potential of satellite products for hazard assessment and early warning in areas of high landslide activity where ground-based data is scarce.

中文翻译：

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地貌，降雨和土壤水分在菲律宾2018年台风山竹引发的滑坡发生中的作用

摘要。在2018年，台风山竹（当地称为Ompong台风）在伊托贡（菲律宾）地区引发了数千起滑坡。570 km ^2上有1101个滑坡的滑坡清单该区域用于研究更容易发生滑坡的地貌特征和土地覆盖，以及导致广泛破坏的降雨和土壤湿度条件。滑坡主要发生在被粘性物质覆盖的树木茂密的草地上，主要是东西向。对卫星降雨（GPM IMERG）和土壤水分（SMAP-L4）的分析发现，除了台风降雨外，土壤水分在触发机制中也起着重要作用。将与台风山竹相关的降雨与2018年未触发区域滑坡事件的33次高强度降雨事件以及先前发布的降雨阈值进行了比较。结果表明：（a）这是一年中最强烈的降雨事件，但不是最高的，（b）尽管卫星数据往往低估了强降雨，但先前公布的区域和全球阈值仍应太低而无法区分滑坡触发事件和非触发降雨事件。这项工作强调了卫星产品在缺乏地面数据的高滑坡活动地区进行危险评估和预警的潜力。