GEOL 106 Lecture Notes - Lecture 27: Mass Wasting, Natural Hazard, Colluvium
25 May 2018
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7.2 Geographic Regions at Risk from Landslides
- significant slopes: landslides
- mountainous areas: higher risk for landslides than areas of low relief
o e.g. West Coast, Rocky Mountains, Appalachian Mountains
o Plains states are flatter → safe from landslides
- Rocky Mountains and coastal mountains of East Coast and West Coast are at high risk
- parts of central Canada like Saskatchewan, Manitoba, eastern Ontario have low risk
- 3 factors that can increase worldwide landslide activity:
1. urbanization and development
2. tree cutting
3. changing global climate patterns → regional increases in precipitation
7.3 Effects of Landslides and Linkages with Other Natural Hazards
EFFECTS OF LANDSLIDES
- 25 people killed each year by landslides, 2.8 to 8.5 billion dollars worth of damages annually
- direct effects:
o hit with or buried in falling debris
o damage homes, roads, utilities that have been constructed on top or side of hill
o block roads and railroads
o can even block shipping lanes
- indirect effects:
o flooding upstream from landslide that blocks river
o transmission of disease from fungal spores distributed by landslides
- 1983 Thistle slide: blocked commerce on major highways and transcontinental rail line for months
LINKAGES BETWEEN LANDSLIDES AND OTHER NATURAL HAZARDS
- landslides and other mass movement are linked to just about every other natural hazard
- earthquakes, volcanoes, storms, fires
- landslides themselves may be responsible for flooding if they form earthen dam across river
o large landslide may also cause tsunami or widespread flooding if it displaces water out of
lake or bay
o e.g. 1963 Vaiont reservoir in northeastern Italy killed more than 2600 people and
displaced water
7.4 Natural Service Functions of Landslides
- creation of new habitats in forests and aquatic ecosystems
- landslides are major source of ecological disturbance in forests:
o can be beneficial for old growth forests by increasing both plant and animal diversity
o aquatic environ.: landslide dammed lakes create new habitat for fish and other organisms
- mass wasting can produce deposits that become mineral resources
o weathering frees mineral grains from rocks and mass wasting transports these minerals
downslope
o heavier minerals, gold and diamonds for example, can be concentrated at base of slope and
in adjacent streams
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Document Summary
7. 2 geographic regions at risk from landslides significant slopes: landslides. Mountainous areas: higher risk for landslides than areas of low relief: e. g. west coast, rocky mountains, appalachian mountains, plains states are flatter safe from landslides. Rocky mountains and coastal mountains of east coast and west coast are at high risk. Parts of central canada like saskatchewan, manitoba, eastern ontario have low risk. 3 factors that can increase worldwide landslide activity: urbanization and development, tree cutting, changing global climate patterns regional increases in precipitation. 7. 3 effects of landslides and linkages with other natural hazards. 25 people killed each year by landslides, 2. 8 to 8. 5 billion dollars worth of damages annually. 1983 thistle slide: blocked commerce on major highways and transcontinental rail line for months. : landslide dammed lakes create new habitat for fish and other organisms. 7. 5 human interaction with landslides expansion of urban areas, transportation networks, natural resource use increased number and frequency of landslides.
