T5: Hazards Flashcards
What is a Hazard?
A potential threat to human life or property
What is a Disaster?
When a hazard seriously affects humans
What is a Natural Hazard?
A hazard caused by natural processes.
e.g. by geophysical, atmospheric and hydrological events
Name:
The 3 types of Natural Hazards
-Geophysical hazards
-Atmospheric hazards
-Hydrological Hazards
Name
Common Characteristics of Natural Hazards
-Little to no warning
-Each has clear origins and distinctive effects
-Involuntary exposure to the risk
-Scale and impact requires emergency response
-Most damage & deaths happen shortly after the hazard, whereas impacts may last into the future
Why do people perceive hazards differently?
-Wealth
-Religion/beliefs/cultures
-Optimism/pessimism
-Frequency
-Knowledge & education
-Documentation of past hazards
-How media/movies/books portray hazards
Define:
Fatalism
The belief that all events are predetermined and therefore inevitable
e.g. the Philippines tends to have a fatalistic response to hazards as they often believe it is just an act of God.
What does the success of responses depend on?
-Magnitude/intensity
-Distribution & size of hazard
-Level of Development
Magnitude- how much energy it has/ how destructive it is.
Define:
Risk
Hazard potential x vulnerability (exposure to a hazardous event)
Define:
Vulnerability
Damage potential + coping capacity (potential for loss)
What is meant by Preparation?
When actions are done prior to the event to prepare the population
What is meant by response?
Actions taken after the emergency to save lives, property and the environment/ecosystem.
What is meant by recovery?
Trying to repair and continue normal life
Rebuild, replant crops
What is meant by Mitigation?
Efforts to reduce the effects/risks associated with hazards.
__________ Management Cycle
Hazard/disaster/risk
What are the 4 stages of the Park Model?
-Pre-disaster
-Relief
-Rehabilitation
-Reconstruction
Define:
Frequency
The distribution of a hazard through time
Define:
Magnitude
Assessment of the size of the impact of a hazard event
Define:
Primary Effects
Effects of a hazard event that results from the event directly
Define:
Secondary Effects
Effects of a hazard that result because of the primary effect
Define:
Soil liquefaction
The process by which saturated, unconsolidated soil or sand is converted into a suspension during an earthquake. It is then able to act like, and flow like, a liquid, particularly when under pressure
What is meant by community resilience?
The sustained ability of a community to utilise available resources to respond to, withstand and recover from the effects of natural hazards.
Resilient communities can minimise the effects of a hazard, making the return to normality as effortless as possible.
Define:
Lithosphere
The rigid, top part of the mantle and the crust
Define:
Asthenosphere
The upper mantle layer of the earth, below the lithosphere. It is semi-molten and believed to be much hotter than the lithosphere.
Name:
The 4 phases of the Hazard Management Cycle
-Mitigation
-Preparedness
-Response
-Recovery
Explain:
The difference between oceanic and continental crust
Continental is thicker and less dense; oceanic is thinner and more dense
Explain:
Slab Pull
1) At destructive plate margins, denser crust is forced under less dense crust
2) The sinking of the plate edge pulls the rest of the plate towards the boundary
Explain:
Ridge Push
1) At constructive plate margins, magma rises to the surface and forms new crust, which is very hot. It heats the surrounding rocks, which expand and rise above the surface of the surrounding crust, forming a slope.
2) The new crust cools and becomes denser. Gravity causes the denser rock to move downslope, away from the plate margin.
3) This puts pressure on the tectonic plates, causing them to move apart.
A.K.A Gravitational Sliding
Besides Ridge Push and Slap pull, what is the lesser known theory for plate movement?
Convection Currents
Define:
Palaeomagnetism
A record of the history of the Earth’s magnetic field, preserved in magnetic minerals in volcanic rocks.
The theory that states that the Earth’s crust is made up of several rigid plates moving relative to one another
Plate tectonic theory
Define:
Constructive Plate Boundary
A plate margin where new crust is generated as the plates pull away from each other.
These are found at mid-oceanic ridges.
A plate margin where two tectonic plates are moving past one another with no addition or destruction of plate margin.
Conservative Plate Margin
Define:
Destructive Plate Boundary
A plate margin where crust is destroyed as two plates converge. These are usually associated with island arcs or young fold mountains.
Who created the theory of continental drift?
Alfred Wegener
He was a German from the 1920s, meaning that his theory was largely dismissed at the time.
Who further developed Plate Tectonic Theory in the 1950s?
Harry Hess
He helped establish Wegener’s earlier theory. He was an American geologist.
Define:
Sea-floor spreading
The theory that states that the ocean floor is moving away from the mid-oceanic ridge and across the deep ocean basin, to disappear beneath continents and island arcs.
List:
Biological Evidence for Continental Drift
- Fossils found in India are comparable with fossils in Australia
- Fossil remains of the reptile Mesosaurus are found in both South America and Southern Africa
- Identical plant fossils have been found in the coal deposits of both India and Antartica.
This suggests that these continents were once joined together
Geological Evidence for Continental Drift
- The ‘jigsaw fit’ of South America and West Africa
- Evidence of similar ancient glacial deposits found in South America, Antartica and India.
- Structural faults in rocks in Brazil and West Africa match when compared
- Similar rock sequences in northern Scotland and eastern Canada.
What does the Park Model look at?
The changing quality of life through different phases of a disaster.
Used by governments and businesses to see who needs more aid.
What does the Hazard Management Cycle Analyse?
The attempts of governments and businesses to reduce losses from hazards and achieve rapid recovery.
What was the name of the Single Supercontinent that broke apart ~200mn years ago?
Pangaea
What are the main driving forces behind tectonic movement?
Slab pull and gravitational sliding
What happens at divergent boundaries?
Plates move apart
e.g. Constructive Plate Boundaries
What happens at convergent plate boundaries?
Plates move towards each other.
e.g. destructive and collision plate boundaries
Which type of plate margin is transform?
Conservative
