Chapter 6: Natural Hazards Flashcards
Structure of earth
Crust - oceanic and continental tectonic plates
Mantle - convection currents move plates
Core - highest pressure to move iron in convection current for magnetic field
Distribution of earthquakes and volcanoes
convention currents in mantle cause tectonic plates to move and collide with each other’s plate boundaries
Types of plate boundaries
constructive (divergent) - plates move apart to form new crust as magma rises (rift valleys)
destructive (convergent) - oceanic and continental come together, oceanic pushed down as more dense into subduction zone, melts so magma rises (volcanoes, ocean trenches)
collision- two continental collide and pushed upwards since same density (fold mountains)
conservative - plates run alongside causing friction (earthquakes)
Formation of earthquakes
tectonic plates locked together due to friction
pressure builds up
strain released
shock waves of energy travel outward from focus underground towards epicentre surface
Factors of amount of damage of earthquakes
depth of focus
geology of area (sedimentary rocks vibrate)
magnitude
vulnerability of population
Impact of earthquake
loss of life
destroyed infrastructure
water bourne diseases (cholera)
landslides
tsunamis
financial losses
Types of volcanoes
Fissure - lava erupts from long thin vent
Shield - runny lava, wider
Dome - thicker, steep convex slope
Strato - viscous lava + ash
Structure of volcano
magma chamber
lava flows (surface of volcano)
volcanic bombs
crater
layers of lava and ash (inside)
ash and gas
side vent (from magma flowing upwards)
Impact of volcanoes
lava flows
gas clouds (co2 and n2o)
volcanic bombs (giant rocks)
pyroclastic flows (fast clouds of ash and gas)
lahars (violent mudflows of ice or snow melt)
loss of life
ash fall
destroyed habitats
Managing impacts before an earthquake
before -
monitor fault lines
satellite technology
earthquake proof designed buildings
retrofit old buildings
education
earthquake drills
Managing impacts during an earthquake
seismometers send signals to rescue stations
emergency supply kits
technology for fast warnings
Managing impacts after an earthquake
search rescue (sniffer dogs/ lifting equipment)
emergency hospitals
emergency aid/ foreign aid
repair and clear up
reconstruct and rebuild
Managing impacts before an volcanic eruption
evacuation plans based on historic ash records
monitored from space or tiltmeters
seismometers detect movement in magma
volcano shelters
education
evacuation
Managing impacts after an volcanic eruption
search and rescue
rebuild buildings
ash fall cleared
settlements abandoned
Distribution of tropical cyclones
between 5 and 20 degrees north and south of the equator
warm tropical water 27 degrees celsius
ocean depth of 60m
Life cycle of tropical cyclone
Disturbance - warm moist air causes thunderstorms to form, pushed by winds
Depression - storms combine and spin
Storm - spiralling winds churn up sea, moisture picked up, grows in strength and speed
Cyclone - rotation around central eye, low pressure in centre creates suction causing storm surges
Impact of tropical cyclones
loss of lives
fishing industry
damage to infrastructure
waterborne diseases
saltwater floods destroy crops
uprooted trees
Managing impacts before a tropical cyclone
track using satellites
predictions and forecasting path of storm
warnings
evacuation plans
emergency training drills
cyclone shelters
education
buildings raised from ground and resistant to winds
Managing impacts after a tropical cyclone
food water shelter
search and rescue of trapped under debris
social networking to reunite families
reconstruct infrastructure
Causes of flooding
heavy rainfall
prolonged rainfall
snow melt
land relief
saturated soil, compact soil
deforestation
cultivation
urbanisation
story surges
tsunamis
rise in sea level
Impacts of floods
loss of life
loss of livestock
loss of crops and rise of food prices
damaged infrastructure
contaminated water stores
waterbourne diseases due to contamination and sewage
financial losses - collapse in tourism agriculture and mining industry
Managing impacts before a flood
storm hydrograph - recurrence interval, rise in sea levels, groundwater flow
flood risk map - geology, slope angle, vegetation cover, land use
build dams
plant trees
flood insurance
risk assessment
Managing impacts after a flood
damaged infrastructure
loss of lives
pumping of water
damage assessment
flood insurance
flood management plans
Human causes of drought
Human -
poor farming practices (overcultivation, cash crops leads to groundwater depletion)
over-abstraction (removing groundwater from wells and aquifers)
deforestation (surface run off and soil erosion)
conflict (migration to drought areas)
