Hazards Flashcards
What is slab pull?
When a plate subducts due to its negative buoyancy (as a result of cooling of the oceanic rock over time), the plate sinking into the mantle pulls the rest of the plate (slab) with it, causing further subduction.
What is ridge push?
When plates at a higher elevation (after being pushed upwards by positive upwelling of hotter mantle rock) move apart due to gravity on it.
- Gravity widens the gap in a process known as gravitational sliding.
What is a hazard?
A potential threat to human life and property caused by an event.
What is a natural disaster?
When a vulnerable population is exposed to a hazard.
What are the 3 types of hazards?
Geophysical
Atmospheric
Hydrological
What are hazards that are both atmospheric and hydrological known as?
Hydrometeorological
What factors affect hazard perception?
- Wealth
- Experience
- Education
- Religion and beliefs
- Mobility
What is fatalism?
The viewpoint that hazards are uncontrollable, and any losses should be accepted as there is nothing to do to stop them.
What tectonic process does gravitational sliding have a role in?
Ridge push
What tectonic process does positive upwelling of hotter mantle rock have a role in?
Ridge push
What tectonic process does subduction have a role in?
Slab pull
What tectonic process does negative buoyancy have a role in?
Slab pull
What is an example of a passive response to hazard risk?
Fatalism
What are examples of active responses to hazard risk?
- Prediction
- Adaptation
- Mitigation
- Management
What is the difference between adaptation and mitigation?
Mitigation = strategies carried out to lessen the severity of a hazard.
Adaptation = Attempting to live with hazards by adjusting lifestyle choices so that vulnerability is lessened.
Example of an adaptation response to hazards
Earthquake proof houses
Example of a mitigation response to hazards:
Sandbags to offset impact of flooding
What is frequency also known as in terms of hazards?
Incidence
What are typically more severe, high incidence hazards or low incidence hazards?
Low incidence hazards
What are the problems with managing low incidence hazards?
- Harder to predict
- Less management strategies are put in place
- More intense when they actually occur
What is intensity in terms of hazards?
The power of a hazard (how strong it is and how damaging its effects are).
What is magnitude in terms of hazards?
The size of a hazard
What is typically used to measure intensity of a hazard?
Magnitude
What is the difference between intensity and magnitude?
Magnitude is definable and numerical.
Intensity relates more to the effects on the person.
What is the Park Model?
A graphical representation of human responses to hazards, including stages of response and a time frame.
What does the steepness of the curve on a Park Model show?
How quickly an area deteriorates and recovers
What does the depth of the curve on a Park Model show?
The scale of the disaster (lower the curve = lower the quality of life)
What are the 3 states in which general quality of life can be in on the Park Model?
(i.e. on the y axis)
- Improvement
- Normality
- Deterioration
What are the 3 stages of response on the Park Model?
(i.e. on the x axis)
- Relief
- Rehabilitation
- Reconstruction
Why is the Park Model useful?
Can be used to compare hazards with each other
What is stage 1 on the Park Model?
- How long is it?
- What typically occurs?
Relief
- Hours/days
- Immediate local response
What is stage 2 on the Park Model?
- How long is it?
- What typically occurs?
Rehabilitation
- Days/weeks
- Restoration of services, coordinated foreign aid, food and water distributed.
What is stage 3 on the Park Model?
- How long is it?
- What typically occurs?
Reconstruction
- Weeks/months/years
- Infrastructure rebuilt, mitigation efforts for future events.
- Restoration to normality (hopefully?)
What does the Hazard Management Cycle outline?
The stages of responding to events.
What are the 4 stages of response in the Hazard Management Cycle (in order)?
Event occurs:
1. Response
2. Recovery
3. Mitigation
4. Preparedness
What is the key problem with hazard models in general?
The unpredictability of some hazards makes the models less effective at accurately representing human responses to hazards.
How thick is the crust in kilometres?
0 to 100km
What is the very top layer of the mantle known as?
Asthenosphere
What lies above the mantle?
Crust/Lithosphere
What 2 layers does the lithosphere consist of:
- Crust
- Upper layer of mantle
What is the lithosphere broken up into?
Tectonic Plates
What is the inner core made up of?
Iron/nickel
- Uranium
What state is the inner core?
Solid
What state is the outer core?
Semi-molten
What is the outer core made up of?
Iron/nickel
What is the mantle made up of?
Rocks high in silicon
What state is the mantle?
Mainly solid rock
What state is the asthenosphere?
Semi-molten
What layer are convection currents located?
Mantle
What are convection currents?
- What are they powered by?
Flows of heat
- Powered by heat from core
What are the 2 types of crust?
- Oceanic
- Continental
What crust layer is dense and easily destroyed by plate movement?
Oceanic crust
What crust layer is less dense and not destroyed by plate movement?
Continental crust
What causes tectonic plates to move?
Convection currents
What are the edges of where plates meet known as?
Plate boundaries/margins
How do convection currents form?
When less dense magma rises, cools, then sinks.
What are the 3 types of plate boundaries?
- Constructive
- Destructive
- Conservative
What type of plate boundary can occur at a continental/continental margin?
Constructive
Destructive
Conservative
What type of plate boundary can occur at an oceanic/oceanic margin?
Constructive
Destructive
Conservative
What type of plate boundary can occur at a continental/oceanic margin?
Destructive
Conservative
What is Paleomagnetism?
The study of rocks that show the magnetic fields of the Earth.
What hazards/landforms develop at a constructive continental/continental plate boundary?
- Rift valleys
- Volcanoes
- Earthquakes
What hazards/landforms develop at a constructive oceanic/oceanic plate boundary?
- Ocean ridges
- Earthquakes
- Volcanoes
What hazard occurs at a conservative plate boundary?
Earthquakes
What hazards/landforms develop at a destructive continental/continental plate boundary?
- Fold mountains
- Earthquakes
What hazards/landforms develop at a destructive oceanic/oceanic plate boundary?
- Ocean trenches
- Island arcs
- Earthquakes
- Volcanoes
What hazards/landforms develop at a destructive continental/oceanic plate boundary?
- Volcanoes
- Fold mountains
- Earthquakes
What plate boundaries do fold mountains develop?
Destructive:
- continental/continental
- continental/oceanic
What plate boundaries do volcanoes develop?
Constructive:
- continental/continental
- oceanic/oceanic
Destructive:
- continental/oceanic
- oceanic/oceanic
What plate boundary do rift valleys develop?
Constructive:
- continental/continental
What plate boundary do ocean ridges develop?
Constructive:
- oceanic/oceanic
What plate boundaries do ocean trenches develop?
Destructive
- oceanic/oceanic
- continental/oceanic
What plate boundary do island arcs develop?
Destructive
- oceanic/oceanic
What plate boundaries do earthquakes occur?
All of them
What are hotspots?
Areas of volcanic activity that are not related to plate boundaries.
What can form around hotspots?
- Volcanoes
- Islands (island chains)
How do hotspots form?
Hot magma plumes from the mantle rise and burn through weaker parts of the crust, forming volcanoes and islands.
Example of a hotspot:
Hawaii
What are constructive plate boundaries also known as?
Divergent
What are destructive plate boundaries also known as?
Divergent
What plate boundary does slab pull and ridge push occur?
Constructive/convergent
How do ocean trenches form?
Denser oceanic plate subducts below continental, leaving an ocean trench.
How do fold mountains form?
Sediment is pushed upwards by subduction. Or, they can be formed from piles of continental crust.
How do rift valleys form?
Land in the middle of a plate separation is forced apart.
What theory does Paleomagnetism support?
Sea Floor Spreading
What is a physical example of paleomagnetism on the ocean floor?
On either side of a constructive plate boundary, symmetrical bands of rock with alternating bands of magnetic polarity, due to the periodic switching of our poles.
What are some examples of volcanic hazards?
- Lava flows
- Lahars (mudflows)
- Jokulhlaups (glacial floods)
- Tephra
- Toxic gases
- Acid rain
- Pyroclastic flows
What is tephra?
Any type of rock that is ejected by a volcano.
How is acid rain caused by volcanoes?
When gases such as sulfur dioxide are released into the atmosphere.
What is the average speed of pyroclastic flows?
- What speed can they reach?
60mph
- Can reach 430 mph
What does VEI stand for?
Volcanic Explosivity Index
