Natural Hazards Flashcards
What is a hazard?
A potential threat to human life and property caused by an event.
Would a hurricane hitting an uninhabited desert island be a hazard?
No, as no people/property is affected.
What is a natural disaster?
When a natural hazard comes into contact with a vulnerable population.
What is the name of the model that shows the difference between hazards and disasters?
Degg’s model.
What are the three major types of geographical hazards?
Geophysical, atmospheric and hydrological.
What is a geophysical hazard?
A hazard caused by land processes. This is usually in the form of tectonic plates.
What is an atmospheric hazard?
A hazard that is caused by atmospheric processes and the conditions created because of these processes.
What is a hydrological hazard?
Hazards caused by water bodies and movement.
Give an example of each type of hazard.
Geophysical: Earthquake, Tsunami, Volcano, Landslide.
Atmospheric: Wildfires, Tropical Storms.
Hydrological: Flooding.
How does a person’s perception of a hazard affect vulnerability?
If people believe there is no chance of a hazard occurring, then they are unlikely to attempt to mitigate a hazard. However, if they fear the hazard occurring they will try and mitigate its effects.
What are the three main ways humans respond to hazards?
Fatalism, Domination and Adaptation.
What is fatalism?
The viewpoint that hazards are uncontrollable natural events and any losses should be accepted as there is nothing that can be done to stop them.
For example, they would accept that their community will flood during the monsoon season.
What is domination?
The viewpoint that science and technological advancements will have the ability to lessen the impacts of a natural hazard.
For example, they would build flood defences in places that flood during the monsoon season.
What is adaptation?
The viewpoint that people can live with the threat of hazards by adapting their way of life.
These people would build their houses on stilts so that the floods do not affect them as much.
What is the frequency of a hazard?
How often a hazard occurs.
For example, every year or once every 100 years.
What is the distribution of a hazard?
Where a hazard appears geographically.
For example, there is a high distribution of volcanoes around the Pacific Ring of Fire.
What is the magnitude of a hazard?
The size of the hazard.
What is the intensity of a hazard?
The amount of damage a hazard causes.
What is the difference between the magnitude and intensity of a hazard?
The magnitude is how large a hazard is and doesn’t change based on location. The intensity is the effect it has on the community.
For example, a 7.0 magnitude earthquake would have a different intensity if it hit a sparsely populated area in the USA compared to a densely populated area in India.
How does a country’s level of development affect the intensity of a hazard?
HICs can usually afford more mitigation strategies and therefore have less severe effects of a hazard.
What are the two models that show how humans respond to hazards?
The Park Model and the Hazard Management Cycle.
What does the Park Model show?
It shows how a hazard affects the quality of life in an area. It then shows the rough timescale of how the quality of life rebounds in the days/weeks/years after a hazard.
What does the steepness of the curve on the Park Model show?
It shows how quickly the quality of life in an area deteriorates and recovers after a disaster.
What does the depth of the curve show in the Park Model?
The scale of the disaster and how much a hazard impacts the quality of life.
The deeper the curve, the greater the drop in quality of life.
What is the main advantage of the Park Model?
It allows hazards to be compared to each other.
What are the four stages of the Hazard Management Cycle?
Preparedness, Response, Recovery, Mitigation.
What is preparedness in the HMC?
Being ready for an event to occur.
For example, public awareness, education and training.
What is response in the HMC?
Immediate action taken after an event.
For example, evacuation, medical assistance, rescue.
What is recovery in the HMC?
Long term responses after a hazard.
For example, restoring services and reconstruction.
What is mitigation in the HMC?
Strategies to lessen the effects of another hazard.
For example, flood defences, warning signals developed.
What are the six layers of the Earth?
Inner core, outer core, mantle, asthenosphere, lithosphere, crust.
What is the structure of the inner core?
A solid ball of iron and nickel. It is very hot due to radioactive decay and it is responsible for the Earth’s internal energy.
What is the structure of the outer core?
Semi molten and made of nickel and iron.
What is the structure of the mantle?
Mainly solid rocks with a high silicon content. However, the top layer of the mantle is semi-molten. This is the asthenosphere.
What is the structure of the asthenosphere?
A semi-molten layer that constantly moves due to flows of heat in convection currents.
What is the structure of the lithosphere?
The lithosphere is broken up into plates. The majority of the lithosphere is within the mantle but the lithosphere includes the crust and tectonic plates.
What is the structure of the crust?
The thin top layer of the lithosphere. Contains two types of solid crust, continental and oceanic.
What is the difference between oceanic crust and continental crust?
Oceanic crust is thinner.
Oceanic crust is denser.
Oceanic crust is younger as it can be destroyed and reformed by plate movement.
What is the general consensus for the reason why tectonic plates move?
Convection currents in the asthenosphere pushing the plates around.
What are the three types of tectonic plate boundary?
Conservative, Constructive and Destructive.
How do the plates move at a destructive plate boundary?
Tectonic plates move towards each other.
How do the plates move at a constructive plate boundary?
The plates move away from each other.
How do the plates move at a conservative plate boundary?
The move parallel to each other.
What tectonic hazards are found at destructive plate boundaries?
Volcanoes and earthquakes.
What tectonic hazards are found at constructive plate boundaries?
Volcanoes and earthquakes.
What tectonic hazards are found at conservative plate boundaries?
Earthquakes but not volcanoes.
What landforms are there at destructive plate boundaries?
Fold mountains, island arcs and deep sea trenches.
What landforms are there at constructive plate boundaries?
Ocean ridges and rift valleys.
How does a volcano form at a destructive plate boundary?
1) The oceanic plate subducts underneath the continental plate due to its higher density.
2) The oceanic crust is melted as it subducts into the asthenosphere.
3) The extra magma created causes pressure to build up.
4) Pressurised magma forces its way through weak areas in the continental crust.
5) Explosive, high pressure volcanoes erupt through the continental plate.
How does a volcano form at constructive plate boundaries?
1) As the plates are moving apart, magma rises in the gap left between the plates.
2) Less explosive volcanoes occur due to the lack of pressure.