3.3 Slope processes

Landslide case study: Vaiont Dam 1963

The main resources for this study are Dave Petley’s Landslide Blog and this PDF file of the 50th anniversary conference ijege-13_bs-genevois-tecca

This is the video used in class.

and here is the short “fly by” video of the animated sequence

Flow Case Study: Aberfan 1966

The coal tip disaster of 1966 in a Welsh mining town of Aberfan is referred to on page 76 of your book. Also look at the model of a slope failure case study from page 77 (Dunedin).  There is a good video to introduce the case of Aberfan:

aberfan diagram

1. What happened? This should describe the event simply saying what movement took place and what were the consequences.
2. Analysis of the event from a geography point of view should show the processes that led the the disaster.
3. Who was responsible for the disaster and what should/could have been done to manage the potential danger ?

aberfan
http://www.nuffield.ox.ac.uk/politics/aberfan/home.htm

All these key facts should be in your study, with description and analysis in detail:

· Spoil heaps located above porous sandstone containing underground springs – concerns had been raised about the stability due to these springs. (National Coal Board ignored these).

· Heavy rain in the days preceding the disaster caused an increase in the water table, water acted as a lubricant to allow subsidence of the spoil heaps.

· Spring had also undercut the heaps, and removed clay destabilising the toe decreasing stability.

· 09:15 am tip 7 collapses sending 100’000 cubic meters of colliery waste down the hillside.

· The landslide gathered speeds of up to 30km/hr.

· Pantglas Junior School was crushed by the landslide – 147 people killed including a whole generation of children who were in assembly at the time.

Summary of contributing factors:

· Human neglect- coal board did not listen to the worries of the miners and locals, continuing to dump on tip 7 despite earlier signs of instability

· Location of springs under spoil heaps – lubricant and undercutting

· Time of day – children all gathered in school

· Heavy rainfall raising water table

British Geological Survey has a wide range of material on slope processes

In concluding your Aberfan case study make sure to refer to the changes in legislation about coal tipping, following the Aberfan disaster. http://www.bgs.ac.uk/mineralsUK/planning/legislation/minewaste.html
http://www.bgs.ac.uk/landslides/How_does_BGS_classify_landslides.html

BGS landslide case studies are worth exploring.

 

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