In recent years, landslides have become a typical monsoon calamity in the Western Ghats region of Kerala, India. In addition to property damage, heavy rainfall (36% above normal) and multiple landslides (4728) killed 48 people in 2018. This tendency continued throughout the monsoon seasons of 2019, 2020, and 2021, resulting in the deaths of over 100 people. Anomalous precipitation is ascribed to the frequent development of low-pressure in the surrounding oceans. Using ground real data and satellite imagery, we evaluated the features of three large landslides in the state of Kerala, which occurred during the monsoon season of 2021. Our investigation found that the Kokkayar landslide was triggered by anthropogenic-related agricultural activities, the Plappally landslide by geomorphic and tectonic processes as well as human involvement, and the Kavali landslide by forest fragmentation with dense vegetation on thin soil. The triggering mechanism for all three of these landslides, however, is the intense rainfall of 266 mm in less than 24 h. Thus, an accurate and precise forecast of rainfall can be used to define a threshold for an early warning, which will be vital for saving lives.

中文翻译：

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印度西高止山脉三起山体滑坡的故事：要吸取的教训

近年来，山体滑坡已成为印度喀拉拉邦西高止山脉地区的典型季风灾害。除财产损失外，2018 年强降雨（比正常水平高出 36%）和多起山体滑坡（4728 起）造成 48 人死亡。这种趋势在 2019 年、2020 年和 2021 年的季风季节持续存在，导致 100 多人死亡。异常降水归因于周围海洋中低压的频繁发展。利用地面真实数据和卫星图像，我们评估了喀拉拉邦 2021 年季风季节发生的三个大型滑坡的特征。我们的调查发现，Kokkayar 滑坡是由与人为相关的农业活动引发的，即 Plappally 滑坡通过地貌和构造过程以及人类的参与，和卡瓦利山体滑坡，森林破碎化，土壤稀薄，植被茂密。然而，所有这三个滑坡的触发机制是不到 24 小时内 266 毫米的强降雨。因此，准确和精确的降雨预报可用于定义预警阈值，这对于挽救生命至关重要。