Raise A Grade Session HazardsPresentation Transcript
Geography Raise a Grade Session - Hazards
Natural Hazards A Natural Hazard is a natural event which is perceived by people as a threat to life and property. It may be generated from within the Earth (earthquakes, volcanoes), occur upon the surface (landslides, avalanches, floods), or happen within the atmosphere (high winds, drought, snow, fog).
Plate Tectonics San Francisco Large earthquakes. Conservative Himilayas Fold mountains, earthquakes. Collision Japan Subduction zone, ocean trenches, island arcs, volcanoes and earthquakes. Destructive Mid-Atlantic Ridge Continuous small volcanoes. Earthquakes. Constructive Location Effects/ Landforms Diagram
Benefits of Tectonic Activity.
Mount St Helens
Earthquakes and large volcano
Monitored for over 2 months before the eruption because the volcano was bulging.
Effects: Landscape – vegetation destroyed, landslides, land covered in volcanic deposits. Farming – Short term loss of crops and livestock, but eventual increase in fertility of soil. Forestry – forests flattened, logging industry destroyed. Communications – rivers blocked, roads and bridges washed away by flooding. Fishing – Raised water temperatures led to loss of fish. People – Evacuation, many inhaled toxic gases. Tourism – Tourists attracted – tourist centre set up in 1993, attracting >1 million visitors a year.
January 1995 at 5.46am
7.2 on the Richter scale.
Lasted for 20 seconds.
616 aftershocks in the same day.
Short Term Effects
172,000 homes collapsed.
Transport network devastated.
Water, gas and electric supplies devastated. Long Term Effects
Businesses forced to close.
Extra jobs created in construction industry.
10 billion yen cost in damages.
Kobes population fell by 33,000 due to people moving away.
Tropical Storms. Seas must be over 27 º c Water is needed to give the storm energy. Rapid uplift of air Faster winds in the centre. Lower pressure in the centre.
Tropical Storms – Bangladesh.
12,000 dead, 28,000 injured.
Loss of income.
Loss of homes.
Emergency services training.
River Floods Causes: Heavy rainfall Saturated ground Snowmelt Deposition of silt Dam failure Deforestation Urbanisation Prevention: Levees Improved services Re-afforestation Flood Action Plan Aid
River Floods – Bangladesh 1998.
30 million homeless
loss of water and electric
loss of industry
Difficulties in Bangladesh:
92% of catchment
outside the country.
Corruption (officials helping
themselves to government money).
Size of problem.
Less water for industry
MEDC e.g.Texas 1998
Lack of rain (for 5 months)
High temperatures (41 ºc)
High demand for water
LEDC e.g. the Sahel
Human activity – clearance
Starvation and famine
Loss of cattle
Lack of rainy season.
Past Paper Question – June 2001
c) Describe the physical processes that are responsible for drought. (4)
Human activity can make the effects of hazards worse. Explain how this happens. (4)
For a natural hazard that you have studied:
Explain the physical processes responsible for the hazard.
How might people be protected from the hazard?
You should refer to any examples you have studied in your answer. (8)