PC Hazards Flashcards
What is a natural hazard?
The threat of substantial loss of life, substantial impact upon life or damage to property that can be caused by an natural event.
What is a natural event?
A naturally occurring physical incident.
What are the three types of natural hazards?
Geophysical - Driven by the Earth’s own internal forces e.g. plate tectonics.
Atmospheric - Driven by processes in the atmosphere.
Hydrological - Driven by water processes.
What are examples of geophysical processes?
Seismic activity such as earthquakes and volcanic events.
What are example of atmospheric processes?
Tropical storms and droughts.
What are examples of hydrological processes?
Floods, storm surges and tsunamis.
What are primary and secondary impacts?
Primary - Impacts that have an immediate effect on the affected area. E.g. destruction of buildings and infrastructure.
Secondary - Impacts that occur after a disaster. E.g. spread of disease, contamination of water sources and economic recession.
What is a natural disaster?
When a natural event causes substantial loss of life, substantial impact upon life or damage to property.
How does a natural event become a Natural Hazard?
If the area at risk has a presence of human life.
What reasons are there for living in areas at high risk of a natural event occurring.
- Fertility of the land e.g. on flood plains and flanks of volcanoes.
- Economic reasons e.g. jobs and employment.
- Its where they have always lived.
How does whether the country affected by a hazard is a LIC or HIC affect the severity of the hazard?
LIC - Generally more resilient, less economically demanding but higher social and economic costs, secondary affects are worse.
HIC - Generally less resilient, more economically demanding but lower social and economic costs, primary affects are worse.
How does the timing of which a hazard occurs affect the severity of the hazard?
The time of year can affect the severity of a hazard due to natural processes which commonly occur during different times in the year e.g. snow in winter.
The time of day can also affect the severity as it is harder to see at night since it is darker.
Both of these factors affect the rescue and evacuation efforts that will occur as a result of a hazard, which can lead to more deaths and longer lasting damage which increases the severity.
How does a countries demographics affect the severity of the hazard that occurs there?
A countries demographics can have a large affect on the severity of a hazard as people can be more or less at risk. For example Russia and Japan which are both high in population. However, if an earthquake was to occur in the centre of each country, the severity would be much greater in Japan due to the high population density compared to Russia.
What is the Hazard Management Cycle?
The Hazard Management Cycle is a plan used to respond, mitigate and prepare for a hazard. It is split into 4 categories: Response, Recovery, Mitigation and Preparedness. Processes that occur are put into the different categories, e.g. medical care is a response and monitoring of seismic activity is preparedness. This is useful to help countries and communities become more resilient to hazards, e.g. NL and flooding.
What is the Park Model?
The Park Model is a model that shows how a country or community has recovered from a hazard. It displays the quality of life against time (which can be hours, days, months or years). When the line is decreasing in gradient it shows the disruption the hazard has caused. When it is increasing in gradient it shows the recovery. The quality of life can be the same, lower or higher than at the start of the model.
What are the 4 layers of the Earth?
Crust - Outermost layer of the Earth (Earth’s surface), Varies from 5-10 km thick under the oceans and 70 km under the continents.
Mantle - The widest layer of the Earth, approximately 2900 km thick, the heat and pressure in this region causes the mainly silicate rocks to be liquid which gets denser the deeper you go.
Outer Core - Semi liquid layer made primarily of iron. The 2 layers in the Core can reach 5000 degrees C.
Inner Core - Solid layer made up of an iron-nickel alloy. The 2 layers in the Core can reach 5000 degrees C.
What is the lithosphere?
The lithosphere is the outermost layer of the Earth and is approximately 100 km thick. It is made of the crust and the upper most part of the mantle which is solid. The bottom of the lithosphere is jagged and has many gaps of which molten rock or magma fills. This zone is where tectonic plates are formed.
What is the aesthenosphere?
This is a plastic-like region just below the lithosphere. The slow movement of the rock in this region can carry the lithosphere causing the tectonic plates to move.
What are the three types of plate margins/boundaries?
Constructive - The two plates are moving away from each other.
Destructive - The two plates are moving towards each other.
Conservative - The two plates are sliding past each other.
What is a mid-ocean ridge? Example?
Submarine mountain ridges that extend for thousands of kilometres along the ocean floor. These form as a result of constructive plate boundaries that are found along areas of ocean. Submarine volcanic eruptions release magma which rapidly cools when in contact with the oceanic water and forms part of the crust. Ridge push results in the oceanic plate moving further from the ridge, allowing more magma to rise.
An example of this is the Mid-Atlantic Ridge that occurs between the North American and Eurasian plates.
What are ridge push and slab pull?
Ridge push - When the higher elevation at a constructive plate boundary causes gravity to push the lithosphere that is further from the ridge.
Slab pull - Following subduction, the lithosphere sinks into the mantle under it’s own weight, helping to ‘pull’ the rest of the plate with it.
What is subduction?
A process which occurs when one tectonic plate slides beneath another (destructive boundary), moving down into the mantle. This usually involves oceanic crust sliding beneath continental crust.
