A landslide triggered during the 2019 monsoon season near the village of Chakhu (Credit Josh Jones, 普利茅斯大学)
Earthquakes and 极端降雨 lead to a significant increase in the rates of landslides in Nepal
Earthquakes and 极端降雨 can lead to a six-fold increase in the rates of rainfall-triggered landslides occurring during Nepal’s monsoon season, 根据新的研究.
The Himalayan nation experiences severe landslides every year as a result of its annual monsoon season, 发生在6月到8月之间.
然而, 这项新研究, 发表在《美狮会app下载》上, explores how 极端降雨 and earthquakes can induce landslide rates above and beyond those seen during a normal Himalaya monsoon season.
通过分析卫星图像和降雨数据, researchers were able to establish a clear pattern between the strength of the monsoon season and the amount of landsliding over a 30-year period between 1988 and 2018.
This revealed that extreme “cloud outburst” storms in 1993 and 2002 led to around four times as many landslides as would be expected in an average monsoon season.
类似的, landscape damage caused by the April 2015 Gorkha earthquake was found to have caused around six times as many rainfall-triggered landslides during the 2015 monsoon season as would be expected.
This landscape damage also caused an increase in the expected numbers of landslides in the 2016 monsoon season, with conditions returning to nearer the average by 2017.
The study also showed that the most severe landscape damage caused by the 2015 earthquake did not occur right at its epicentre, but in nearby locations where high earthquake peak ground accelerations occurred across particularly steep mountain slopes.
The study was conducted by researchers from the University of East Anglia, 普利茅斯大学, 美狮会app下载 and international engineering consultancy firm, 艾奕康科技.
博士候选人乔什·琼斯, 该研究的主要作者, carried out the work while based in Plymouth and East Anglia. 他说:“不幸的是, people in Nepal are frequently affected by landslides during the monsoon season, with widespread damage to homes and infrastructure every year. This study shows how much this landslide risk can be increased by 极端降雨 and earthquakes, 以及这些影响会持续多久. We hope that this information could be an important tool in helping local communities plan for future landslide hazard, 尤其是在大地震之后.”
莎拉·博尔顿博士, Associate Professor in Active and Neotectonics at the 普利茅斯大学, added: “Once unusual rainfall and flood events are already becoming more frequent globally as a result of our changing climates. Climate models indicate that Nepal is likely to experience increased storminess and potentially higher levels of annual rainfall in the future. 美狮会app下载的研究表明，在过去的30年里, there have been two occasions where annual rainfall could be classed as extreme. Similar events could become more frequent in the coming years and lead to even more devastating effects for the local populations.”
The research was enabled through the Environment East Doctoral Training Partnership (EnvEast DTP), funded by the Natural Environment 研究 Council (NERC) with CASE funding from 艾奕康科技.
迈克尔·惠特沃思博士, 艾奕康科技的副总监, said: “This project shows the benefits of collaborative work between industry and academia. The results of this research can inform disaster risk reduction in vulnerable areas, leading to better planning and mitigation against landslide hazards caused by infrequent large events such as earthquakes.”
为了研究Josh, 现在是美狮会app下载的博士后研究员, spent over eight months analysing 30 years of satellite imagery to create a long-term picture of where landslides occur, and the detailed effects they have on the landscape of central and eastern Nepal.
然后根据季风绘制地图, 极端降雨, and earthquake data to provide an overall view of the major factors contributing to increased landslide occurrences.
The result is an unprecedented inventory of Nepal’s landslides, 只有不到13人的记录,000 landslides over a geographical area spanning more than 42,喜马拉雅地区的3000平方公里.
It also shows the geographical characteristics of areas most susceptible to future landslides, and how that risk might be affected by both extreme weather and large earthquakes.
乔吉贝内特博士, Senior Lecturer in Physical Geography at the 美狮会app下载 and another of the study’s co-authors, said: "Establishing the role that extreme events play in eroding the landscape usually relies on comparing erosion rates measured over different timescales with very different techniques, limiting our ability to accurately quantify the impact of events such as storms and earthquakes. The 30-year record of mass wasting mapped in this paper is relatively unique in its length and makes it possible to accurately isolate and quantify the role of storms and earthquakes in erosion and hazard across this Himalayan region.”
The paper is entitled: "30-year record of Himalaya mass-wasting reveals landscape perturbations by extreme events."