On January 4, 2010, in the remote Hunza Valley of Northern Pakistan a massive landslide buried the village of Attabad, destroyed 26 houses and killed 20 people. The landslide dammed Hunza River and formed an extensive lake of 100m depth. Until the end of July 2010, 381 houses were ruined; out of which 141 were directly affected by Attabad landslide...
... A second period of displacement was observed in 2004, when the cracks extended longitudinally and transversely into cultivated fields and the populated area of Atta Abad Village. Surface failure features also appeared at the toe of the affected area(Hayat et al., 2010). The situation was exacerbated by the 2005 Kashmir earthquake, which destroyed several houses, damaged others and expedited slope movement. ...
Natural processes, such as earthquakes, landslides and landslide-dam outburst floods, meteoric floods, and glacially-derived floods, have over even just the last few years within the Hindu Kush-Karakoram-Himalayan Region caused several billions of dollars' worth of damage to hydropower infrastructure alone, let alone wider societal losses, thousands of fatalities, and hundreds of thousands of displaced and homeless people. It is evident that the consequences of extreme hydro-meteorological and geological processes have not been considered adequately in the development of major infrastructure projects, such as hydropower schemes, in this region. Analysis of a number of notable natural disasters that have occurred within the last decade in the Hindu Kush-Karakoram-Himalayan Region has aided the understanding of the causes and behaviour of the responsible natural processes and their sequencing. Rather than examine each as an example of a specific type of event, it has been necessary to review a combination of geological preconditioning factors and the interaction with recent and current physical processes, including the effects of changing climate. Three disasters that have occurred between 2010 and 2016 are described from Pakistan, northern India, and Nepal to illustrate the combination of physical processes in each case. Lessons learned from each with respect to geohazard assessment will be highlighted. In addition, it is also germane to examine how Massive Rock Slope Failures influence active landslides and the development of future major rock instabilities. Many of these events and phenomena further demonstrate the role of the physical preconditioning of sites in shaping the nature and scale of subsequent natural disasters. Better understanding of the physical processes involved in destabilisation of steep mountain flanks and the role of climate change is helping to refine the way in which these mountain hazards can be assessed. The relationships between these physical processes and the timescales over which they operate are critical in framing appropriate Disaster Risk Management strategies for major infrastructure developments. It is by understanding better the interrelationships between preconditioning factors and ongoing geological and hydrological processes, including the effects of climate change, that integrated geohazard assessment methodologies can be developed. These in turn can be used to help inform Disaster Risk Management strategies and action plans. There is substantial ongoing and projected investment worth multiple-tens of billions of US dollars in especially hydropower and road infrastructure in high mountain environments in the Hindu Kush-Karakoram-Himalayan Region over the next decade and beyond. It is crucial to the performance and, in some cases, survival of these investment projects that robust integrated geohazard assessments are undertaken and incorporated into flexible forward-looking Disaster Risk Management plans.
Hazards in reservoirs and lakes arising from subaerial landslides causing impact waves (or ‘lake tsunamis’) are now well known, with several recent examples having been investigated in detail. The potential scale of such hazards was not widely known at the time of the Vaiont dam project in the 1950s and early 1960s, although a small wave triggered by a landslide at another new reservoir nearby in the Dolomites (northern Italy) drew the possible hazard to the attention of the Vaiont project’s managers. The Vaiont disaster in 1963 arose from a combination of disparate and seemingly unrelated factors and circumstances that led to an occurrence that could not have been imagined at that time. The ultimate cause was a very large landslide moving very rapidly into a reservoir and displacing the water. The resulting wave overtopped the dam to a height of around 175 m and around 2000 people were killed. This paper identifies and examines all of the issues surrounding the Vaiont dam and landslide in order to identify causal factors, contributory factors (including aggravating factors) and underlying factors. In doing so, it demonstrates that the disaster arose from the Vaiont dam project and cannot be attributed simply to the landslide. Underlying geological factors gave rise to the high speed of the landslide, which would have occurred anyway at some time. However, without the contributory factors that account for the presence of the reservoir, i.e. the choice of location for the project and management of the project with respect to a possible landslide hazard, there would have been no disaster. Indeed, the disaster could have been avoided if the reservoir could have been emptied pending further ground investigations. Understanding of this case provides many lessons for future dam projects in mountainous locations but also highlights an ongoing and perhaps under-appreciated risk from similar events involving other water bodies including geologically recent lakes formed behind natural landslide dams.