GEOL 106 Lecture Notes - Lecture 47: Landslide, Medieval Warm Period, Little Ice Age
26 May 2018
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GLACIAL HAZARDS
- glaciers are huge, ,actively flowing masses of ice and rock debris whose movement and melting have
been responsible for property damage, injuries, death
o irregular cracked surfaces → hazards to people crossing them for exploration or
mountaineering
o surface snow may hide deep cracks in ice = crevasses
o on some steep slopes: glacial ice falling from above = hazard
- changes in flow of glaciers present hazards that have been well documented
- glaciers can expand or surge and overrun villages, fields, roads, other structures
o may also advance and cross stream valley → produces ice dam and temporary lake
o such da can lead to major downstream flooding if lake water undercuts or spills over ice
dam or if dam is otherwise destroyed
- if leading edge of glacier retreats upslope → blocks of ice may fall off in ice avalanches into valley
blow → destroys property and perhaps taking lives
o 1962 Huascaran Avalanche: combined ice and debris avalanche → killed 4000 people,
destroyed villages
o 1970 Peru avalanche due to earthquake killed 20 000 people and buried several villages
in debris
o September 2002: huge mountain glacier broke loose in southern Russia → torrent of ice,
mud, rocks downslope → debris buried villages, 100 people dead
- when glaciers move from land into sea: calving = large blocks of ice break off from front of glacier
and drop into water
o produces blocks of floating ice = icebergs which can float into shipping lanes and create
hazard
o April 14 1912 Titanic (England to US)
- large icebergs can be beneficial → looked as sources of fresh water if they could be towed to areas
where water is scarce
- glaciers ay trigger other hazardous events
o active volcanoes hat have glaciers on their slopes
o volcano erupts → melt ice and trigger downslope movement of glacial ice and volcanic
유갼 → lahars
12.4 How We Study Past Climate Change and Make Predictions
- data are available for 3 main time periods
1. instrumental record:
a. from 1880
b. temperature measurements have been made at various locations on land and in
oceans
c. earliest records are form late 17th and early 18th centuries and network of stations has
significantly increased over time
d. 1000 records from late 19th century
e. today: temperature is measured at about 7000 stations around world
f. concentration of CO2 measured since 1960
g. measurement of production of solar energy since past several decades
2. historical record:
a. people’s recollectios of Medieval War Period ad Little Ice Age
b. ship logs, traveller’s diaries, farers’ crop records
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