Hazards Flashcards
Difference between oceanic and continental crust
Oceanic crust: more dense, hard balsaltic, less thick
Continental crust: Less dense, soft granite, thicker
Difference between a natural event and a natural hazard
Natural event = feature that occurs due to earth’s processes
Natural hazard = when a natural event can cause loss of life or damage to property
Geophysical hazards
Geophysical hazard = caused by earth’s processes - internal (tectonic), external (mass movement)
Hydrological hazards
Hydrological hazards = caused by occurence/movement/distribution of water
Atmospheric hazards
Atmospheric hazards = within the atmosphere eg exteme weather events
When do hazards become a disaster?
Hazards become a disaster in a vulnerable population -> Dregg’s model
Plate boundaries
Plate boundaries:
-Collision
-Transform/Conservation
-Divergent/Constructive
-Convergent
Collision plate boundary
Collision plate boundary:
-Equal density, folds upwards and creates mountains
-Earthquakes only, himalayas
Transform/Conservative boundary
Transform/Conservative argument:
-Plates slide past eachother, friction released
-Earthquakes only
-San-andreas fault in California
Divergent/Constructive boundary
Divergent/Constructive boundary:
-Plates move away from eacother
-Forms Ocean Ridge system
-Underwater mountains + volcanoes
-Shield volcanoes and easthquakes
-Rift valleys
-Mid-alantic Ridge
Convergent boundary
Convergent boundary:
-Denser ocean plate subducts -> downward placement forms a deep-sea trench -> sediment unfolded
-Composite volcanoes and earthquakes
Why do plate boundaries move?
Plate boundaries move due to ridge push, slate pull and convection currents
Evidence of continental drift
Evidence of continental drift:
-Geological fit (similar rock types in different areas)
-Tectonic fit (plate movement causes land movement)
-Jigsaw fit (countries fit together)
-Paleomagnetism
-Fossil evidence
Factors that affect viewpoints of how dangerous hazards are
Factors that affect viewpoints of how dangerous hazards are:
-Wealth
-Experience
-Education
-Religion and beliefs
-Mobility
Passive response to a hazard
The passive response to a hazard = fatalism = viewpoint that hazards are uncontrollable natural events and losses should be accepted
Active responses to a hazard
Active responses to a hazard:
-Prediction
-Adaptation
-Mitigation
-Management
-Risk sharing
Aspects of hazards that could affect human responses
Aspects of hazards that could affect human responses:
-Frequency
-Distribution (where the hazard occurs)
-Intensity
-Magnitude
-Level of development
The Park Model
The Park Model is a graphical representation of human responses to hazards
-Step 1 = Relief (hrs/days) = immediate local response
-Step 2 = Rehabilitation (days/weeks) = Services, shelters, food and water
-Step 3 = Reconstruction (weeks/yrs) = restoring the area back to normal
Outline the earth’s structure
Earth’s structure:
-Inner core = solid ball of iron/nickel, hot due to pressure and radioactive decay
-Outer core = semi-molten, iron/nickel
-Mantle = solid rock, silicon, semi-molten magma layer called aesthenosphere with lithosphere ontop
-Crust = thin top of lithosphere
Outline the movement of convection currents
Convection currents:
-Heat from core convects through mantle
-hot magma rises as it becomes less dense
-magma cools at top and sinks
-this movement causes tectonic plates to move
Hazards caused by volcanoes
Volcanic hazards:
-Lava flows
-Lahars (mudflows)
-Glacial floods
-Tephra (rock ejected from the volcano)
-Toxic gases
-Acidic rain
-Pyroclastic flows
Volcano distribution
Volcano distribution - along constructive or deconstructive plate boundaries or hotpots - ring of fire
Volcano magnitude
Volcano magnitude is measured using the Volcanic Explosivity Index (VEI)
Primary impacts of volcanic hazards
Primary impacts of volcanic hazards:
-Damaged ecosystems
-Businesses destroyed
-People killed
-Homes destroyed
-Government buildings destroyed
Secondary impacts of volcanic hazards
Secondary impacts of volcanic hazards:
-Acidic rain
-Loss of jobs
-Forest fires
-Government conflicts
Responding to a volcanic hazard
Responding to a volcanic hazard:
-Prevention - not allowing people near
-Preparedness - increased monitoring, education
-Mitigation - strengthening buildings, evacuation zones
-Adaptation - moving away from risky areas, tourism for better opportunities to increase mitigation
What are the immediate responses to volcanic eruptions?
Immediate response:
-Aid
-Warnings and monitoring
-Evacuation
-Temporary infrastructure (shtlers)
What are the long-term responses to volcanic eruptions?
Long-term responses to volcanic eruptions:
-Education
-Relocation using resettlement programmes
-Improve locale economy
-Rebuild infrastructure