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ENV-3A1Y: Natural Hazards: 2006 - 7

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Land on Main Highway at km 365 west of Sao Paulo: August 2002. 14,607 ... Field Excursion: Thursday Week 5 12 17. Bring Field Clothing and a packed lunch ... – PowerPoint PPT presentation

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Title: ENV-3A1Y: Natural Hazards: 2006 - 7

1
ENV-3A1Y Natural Hazards 2006 - 7

Landslide Hazards
N.K. Tovey
?.?.????

14,607 days ago today Exactly 40 years ago next
Saturday
Landslide on Main Highway at km 365 west of Sao
Paulo August 2002
2
ENV-3A1Y Natural Hazards 2006 - 7

Lecture 1 Wednesday Week 42
Introduction
Landslides as a Hazard and their consequences
background to why they occur
Lecture 2 Thursday Week 4 12 13 EF 1.01
Types of Landslide
Lecture 3 Thursday Week 4 14 - 15
Landslide Warning systems
Lecture 4 Wednesday Week 5 09 10 EF 1.01
Landslide and Slope Management
Field Excursion Thursday Week 5 12 17
Bring Field Clothing and a packed lunch

3
ENV-3A1Y Natural Hazards 2006 - 7

Aims of the course
An introduction to Landslide Hazard Management
Factor of Safety
the causes
Why they occur
Can we predict them
the consequences
The types of landslide
Landslide Warning
Development of the Hong Kong System and what was
learnt
Strategic Planning for the future
Slope management

4
ENV-3A1Y Natural Hazards 2006 - 7

Landslides as a Hazard
Grossly Under Represented as a Hazard
Often treated as a secondary issue
e.g Rain Storm Disasters of 18th June 1972 in
Hong Kong
2 major landslides each killing over 60 people
No one was killed by drowning/flooding

5
ENV-3A1Y Natural Hazards 2006 - 7

Landslides associated with
Heavy Rain (Tropical Cyclones)
500 landslides affected man in Hong Kong 28th
May to 2nd June 1982.
As a result of NKTs actions Yuen Mo village
ceased to exist.
Earthquakes
Cause liquefaction and rise of pore pressures
Volcanic Eruptions

6
ENV-3A1Y Natural Hazards 2006 - 7

14607 days ago today at 0915
N K Tovey a second year PhD student was
listening to a lecture by Andrew Schofield.
Theme of lecture was Landslide Hazards
At 0915 he turned his attention to a landslide
disaster which had occurred a few year earlier in
Belgium.
A colliery tip collapsed killing around 20 people
in the village.
At precisely the time he was speaking about
the disaster
gtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgt

7
ENV-3A1Y Natural Hazards 2006 - 7

Aberfan 21st October 1966
Tip 7 collapsed, engulfed Pantglas School and
parts of the village killing 144 mostly children

8
ENV-3A1Y Natural Hazards 2006 - 7

Geotechnics the discipline needed for detailed
analysis
"the application of the laws of mechanics and
hydraulics to the mechanical problems relating to
soils and rocks"
Factor of Safety (Fs)

Forces resisting landslide movement arising from
the inherent strength of the soil.
Fs
Forces trying to cause failure (i.e. the
mobilizing forces).
Fs gt 1 stable
But is it?
Fs 1 just stable
But is it?
Fs lt 1 unstable
9
berms
Heave at toe