The analysis of the spatial patterns and controls governing the global occurrence of fatal landslides

In the research presented here, a global inventory of fatal landslides has been generated allowing the investigation of the spatial distribution and temporal occurrence of mass movement events. There are important regional differences within these data with Asian fatalities being characterised by high frequency, low magnitude landslide events. In comparison, high magnitude events were found to be responsible for the high fatality totals in the Americas. This research has demonstrated that the spatial distribution of fatal landslides is best explained by a combination of physical and social factors and has yielded some interesting results.87% of the fatal landslide events recorded within the database were triggered by high intensity of prolonged rainfall events associated with tropical cyclones or monsoon rainfall that are compounded in areas of high relief associated with tectonically active mountain belts. Increasing landslide impacts are often associated with less developed countries, where there is rising population density, rural to urban migration, growth of megacities, and severe land degradation. However, the results indicate that the occurrence of landslide fatalities are not simply a function of level of development of a country or population density but that fatalities predominantly occur within middle income countries and rural areas which are increasingly vulnerable to landslide disasters. This can be attributed to changes in physical systems, most notably climate variation

Landscape, Livelihoods and Risk: Community Vulnerability to Landslides in Nepal

The occurrence of fatal landslides in Nepal is increasing with time, faster than the effects of monsoonal variations. Possible explanations for the trends observed include: land-use change, population growth, and the development of transport infrastructure. However, to date, there is little evidence to support these postulated causes and very little research into the nature of landslide vulnerability in the Nepalese context. This research takes an interdisciplinary approach to examine, and where necessary, challenge a series of assumptions made regarding landslide vulnerability in Nepal with a view to developing a better understanding of social vulnerability and its underlying causes. Firstly, a bottom up livelihoods based approach is adopted to examine the following research questions: (1) Who is vulnerable to landslide hazard?; (2) Why do people occupy landslide prone areas?; and (3) How do ‘at risk’ rural communities perceive and respond to landslide hazard and risk? In so doing, this thesis approaches the question of landslide vulnerability from the perspective of the vulnerable people themselves. Secondly, the research explores how scientists and policy experts view landslide risk management in Nepal and how policy is subsequently informed and shaped. The findings highlight the impact of infrastructure projects in rural Nepal. Within the Upper Bhote Koshi Valley clear transitions in settlement patterns and rural livelihoods (and thus the occupation of landslide prone areas) have been seen over time. For the majority of households, their decision to occupy these areas is driven by the economic and social benefits associated with the road. Landslide risk therefore emerges not just from societal marginalisation but also from situations of relative prosperity. The findings suggest that occupants of landslide prone areas have a good understanding of landslide hazard and its associated risk. However, these risks are contextualised in relation to other social concerns. The significance of the findings for landslide policy and practice are addressed along with different actors’ views of landslide risk management in Nepal

The neglected country(side): Earthquake risk perceptions and disaster risk reduction in post-Soviet rural Kazakhstan

© 2020 The Authors While increasing resilience to earthquakes in the global South has become a major research and policy goal, the focus has largely been on rapidly expanding urban areas. Rural areas are often neglected despite the fact that rural residents make up a significant proportion of the population exposed to earthquakes in many low and middle-income countries. Central Asia is a case in point. Drawing on empirical research undertaken in the Central Asian Republic of Kazakhstan, this paper explores local perceptions of and responses to earthquake hazard and risk among rural householders. The primary data are derived from a survey of 302 households conducted across six rural communities in South Kazakhstan oblast (now Turkistan oblast), supplemented by 10 focus group discussions with rural residents. The findings show little awareness of earthquakes or concern about the potential occurrence of a high magnitude earthquake in the future. This reflects, at least in part, a lack of direct experience of all but minor earthquakes. As a result, we see little evidence of the presence of a seismic culture. Only a small number of respondents had received guidance on how to prepare for, or respond to, earthquakes, and few householders had taken any action to reduce the risk faced. We reflect on the findings in the context of Kazakhstan's Soviet past and its transition to a post-Soviet future. We argue that acknowledging this past is essential to understanding local level decision-making and to informing future disaster risk reduction interventions in rural areas

Between a rock and a hard place: Vulnerability and precarity in rural Nepal

Drawing on a local study on Nepal’s Terai, this paper explores the nature of livelihood exposure to shocks and stresses among rural households in two Village Development Committees in Sunsari District. The primary data are derived from a 117 household survey supplemented by 19 purposefully sampled follow-up interviews. The paper opens with a discussion of the changing nature of exposure in the global South, distinguishing between inherited vulnerability and produced precarity. We then provide background to the research site and the research methods. In the core empirical part of the paper we unravel and distinguish between the livelihood threats and opportunities faced by households in the area and use these to reflect on the nature of ’exposure’, its historical origins and contemporary (re)production. The final part of the paper uses the Nepal case to build a more general argument, proposing that if we are to understand the puzzle of continued livelihood exposure and uncertainty in the context of aggregate economic expansion we need to identify and interrogate the processes that may, at the same time, produce wealth and reduce vulnerability, while also generating precarity

Global Mapping of Citizen Science Projects for Disaster Risk Reduction

Citizen science for disaster risk reduction (DRR) holds huge promise and has demonstrated success in advancing scientific knowledge, providing early warning of hazards, and contributed to the assessment and management of impacts. While many existing studies focus on the performance of specific citizen science examples, this paper goes beyond this approach to present a systematic global mapping of citizen science used for DRR in order to draw out broader insights across diverse methods, initiatives, hazards and country contexts. The systematic mapping analyzed a total of 106 cases of citizen science applied to DRR across all continents. Unlike many existing reviews of citizen science initiatives, relevance to the disaster risk context led us to ‘open up’ our mapping to a broader definition of what might constitute citizen science, including participatory research and narrative-based approaches. By taking a wider view of citizen science and opening up to other disciplinary practices as valid ways of knowing risks and hazards, we also capture these alternative examples and discuss their relevance for aiding effective decision-making around risk reduction. Based on this analysis we draw out lessons for future research and practice of citizen science for DRR including the need to: build interconnections between disparate citizen science methods and practitioners; address multi-dimensionality within and across hazard cycles; and develop principles and frameworks for evaluating citizen science initiatives that not only ensure scientific competence but also attend to questions of equity, responsibility and the empowerment of those most vulnerable to disaster risk

Simple guidelines to minimise exposure to earthquake-triggered landslides

Reducing landslide risk in many mountainous regions is most effectively achieved by reducing exposure to landslides, because landslides cannot be predicted or stopped and engineering solutions are generally impractical or impossible. Because landslide hazard is very site-specific, available hazard maps may not be detailed enough, or contain appropriate and up-to- date information, to inform decision-making. We use our experience of studying the characteristics of landslides in recent large earthquakes to describe three simple guidelines that can be used to minimise exposure to future earthquake-triggered landslide hazard. The most effective measure is to choose a location that minimises the angle to the skyline, and to keep that angle below 25° if at all possible. It is also important to avoid steep channels (those with slopes of >15°), especially if there are many steep hillsides upstream. Finally, the slope of the ground at your location should always be minimised. These guidelines do not specify where landslides will occur, but can be used to distinguish between areas which are more or less likely to be affected by landslides in a large earthquake. They can be used to reduce risk before an earthquake occurs by helping to inform decisions on where to situate key infrastructure, such as schools or health posts. They can be used to inform decisions about the locations of houses, markets, or other areas where people are likely to spend considerable periods of time, or for deciding on appropriate types of land use. The guidelines can also be used in disaster preparedness and response planning, by identifying suitable evacuation routes and open spaces for use as evacuation sites or emergency shelters. We provide some brief guidance on what to do immediately after an earthquake in order to minimise exposure to landslides, and discuss the relevance of these guidelines for protecting against rainfall-triggered landslides which may occur more frequently

Satellite-based emergency mapping using optical imagery: experience and reflections from the 2015 Nepal earthquakes

Landslides triggered by large earthquakes in mountainous regions contribute significantly to overall earthquake losses and pose a major secondary hazard that can persist for months or years. While scientific investigations of coseismic landsliding are increasingly common, there is no protocol for rapid (hours-to-days) humanitarian-facing landslide assessment and no published recognition of what is possible and what is useful to compile immediately after the event. Drawing on the 2015 Mw 7.8 Gorkha earthquake in Nepal, we consider how quickly a landslide assessment based upon manual satellite-based emergency mapping (SEM) can be realistically achieved and review the decisions taken by analysts to ascertain the timeliness and type of useful information that can be generated. We find that, at present, many forms of landslide assessment are too slow to generate relative to the speed of a humanitarian response, despite increasingly rapid access to high-quality imagery. Importantly, the value of information on landslides evolves rapidly as a disaster response develops, so identifying the purpose, timescales, and end users of a post-earthquake landslide assessment is essential to inform the approach taken. It is clear that discussions are needed on the form and timing of landslide assessments, and how best to present and share this information, before rather than after an earthquake strikes. In this paper, we share the lessons learned from the Gorkha earthquake, with the aim of informing the approach taken by scientists to understand the evolving landslide hazard in future events and the expectations of the humanitarian community involved in disaster response. Please read the corrigendum first before accessing the articl

Satellite-based emergency mapping using optical imagery: experience and reflections from the 2015 Nepal earthquakes

Landslides triggered by large earthquakes in mountainous regions contribute significantly to overall earthquake losses and pose a major secondary hazard that can persist for months or years. While scientific investigations of coseismic landsliding are increasingly common, there is no protocol for rapid (hours-to-days) humanitarian-facing landslide assessment and no published recognition of what is possible and what is useful to compile immediately after the event. Drawing on the 2015 Mw 7.8 Gorkha earthquake in Nepal, we consider how quickly a landslide assessment based upon manual satellite-based emergency mapping (SEM) can be realistically achieved and review the decisions taken by analysts to ascertain the timeliness and type of useful information that can be generated. We find that, at present, many forms of landslide assessment are too slow to generate relative to the speed of a humanitarian response, despite increasingly rapid access to high-quality imagery. Importantly, the value of information on landslides evolves rapidly as a disaster response develops, so identifying the purpose, timescales, and end users of a post-earthquake landslide assessment is essential to inform the approach taken. It is clear that discussions are needed on the form and timing of landslide assessments, and how best to present and share this information, before rather than after an earthquake strikes. In this paper, we share the lessons learned from the Gorkha earthquake, with the aim of informing the approach taken by scientists to understand the evolving landslide hazard in future events and the expectations of the humanitarian community involved in disaster response

Modelling post‐earthquake cascading hazards: Changing patterns of landslide runout following the 2015 Gorkha earthquake, Nepal

Coseismic landslides represent the first stage of a broader cascading sequence of geohazards associated with high-magnitude continental earthquakes, with the subsequent remobilisation of coseismic landslide debris posing a long-term post-seismic legacy in mountain regions. Here, we quantify the controls on the hazard posed by landslide remobilisation and debris runout, and compare the overlap between areas at risk of runout and the pattern of post-seismic landslides and debris flows that actually occurred. Focusing on the 2015 Mw 7.8 Gorkha earthquake in Nepal, we show that the extent of the area that could be affected by debris runout remained elevated above coseismic levels 4.5 years after the event. While 150 km2 (0.6% of the study area) was directly impacted by landslides in the earthquake, an additional 614 km2 (2.5%) was left at risk from debris runout, increasing to 777 km2 (3.2%) after the 2019 monsoon. We evaluate how this area evolved by comparing modelled predictions of runout from coseismic landslides to multi-temporal post-seismic landslide inventories, and find that 14% (85 km2) of the total modelled potential runout area experienced landslide activity within 4.5 years after the earthquake. This value increases to 32% when modelled runout probability is thresholded, equivalent to 10 km2 of realised runout from a remaining modelled area of 32 km2. Although the proportion of the modelled runout area from coseismic landslides that remains a hazard has decreased through time, the overall runout susceptibility for the study area remains high. This indicates that runout potential is changing both spatially and temporally as a result of changes to the landslide distribution after the earthquake. These findings are particularly important for understanding evolving patterns of cascading hazards following large earthquakes, which is crucial for guiding decision-making associated with post-seismic recovery and reconstruction