Natural + Tectonic Hazards Flashcards
definiton of natural hazard
A hazard is an event which has the potential to cause harm to the environment, people or the economy
A natural hazard is an event caused by environmental processes and would occur without the presence of humans
Factors affecting hazard risk
Population: As the world population increases, more people live in areas which are vulnerable to natural hazards
Urbanisation and population density: Urban areas are more densely populated, increasing the numbers of people at risk
Frequency and magnitude: How often a hazard event occurs as well as the size and strength of the event
Level of development: High Income Countries (HICs) are more prepared and are more able to cope with the effects than Low Income Countries (LICs) and Newly Emerging Economies (NEEs)
Prediction: Some hazards such as earthquakes are impossible to predict and so people have no warning
Human activities: Some human activity such as deforestation and urbanisation increase the level of hazard risk
The structure of the Earth
Inner core: About 1400km in diameter, a solid and dense layer composed of iron and nickel with temperatures of about 5500°C
Outer core: About 2100km thick, a semi-molten metal layer with temperatures between about 5000-5500°C
Mantle: About 2900km thick, a semi-molten layer which is less dense than the outer core
Crust: The thickness varies, and is made up of two types of crust
Types of plate boundary
- Constructive
- Destructive
- Conservative (transform)
- At a constructive boundary the plates are moving apart
The Mid Atlantic Ridge is an example of a constructive plate boundary
Both volcanic eruptions and earthquakes can occur at this type of plate boundary - At a destructive plate boundary the plates are moving together
The denser, heavier oceanic plate subducts under the lighter, less dense continental plate
The boundary between the Nazca plate and the South American plate is one example
Both volcanic eruptions and earthquakes occur at this type of plate boundary
3.At a conservative (transform)boundary the plates move passed each other in opposite directions or in the same direction at different speeds
Earthquakes are the only hazard at this type of boundary
Primary effects of :
* earthquakes
* volcanic eruptions
- Buildings, homes and farmland destroyed/damaged
- People injured/killed
- Transport routes destroyed/damaged
- Aircraft grounded due to ash in the atmosphere
- Contaminated water supply
- Ash fall buries houses/crops
Secondary effect of:
* earthquakes
* volcanic eruptions
- Economy slows as businesses take time to re-establish and money is spent on rebuilding
- Aid struggles to reach those in need due to damaged/destroyed transport routes
- Lack of clean water leads to disease
- Damaged/destroyed homes lead to homelessness
- Flooding caused by ice/snow melting on the volcano slopes may also cause lahars
- Food prices increase
Example Case Study: Nepal
- general details
- cause
- effects
- immediate response
- long term responses
Details
* Nepal is one of the poorest countries in the world
* Nepal is a landlocked country
* In April 2015, Nepal was struck by an earthquake magnitude 7.8
Cause
* Nepal is located on a collision boundary between the Indian and Eurasian plates
Effects
* Approximately 9000 deaths
* Over 20,000 people injured
* 3.5 million homeless
Immediate responses
* Donations of money and aid from around the world
* tent cities setup in kathmandu forhomeless
Long term response
* Landslides were cleared and roads repaired to
* Schools were rebuilt
* Earthquake drills were introduced to provide people with education about what to do in the event of an earthquake
* Stricter building codes with more enforcement
Why People Live in Areas at Risk
- Fertile soils: The ash and cooled lava contain many minerals which lead to high yields of crops
- Tourism: Many people want to visit areas where there are active volcanoes, this increases the number of jobs available
- Minerals and precious stones: These can be mined and sold providing work for local people
- Geothermal energy: As the magma is closer to the surface the heat can be used to generate geothermal energy
- ** Creating new land area**: Once the lava and ash have cooled, new land areas are formed
What are four key management strategies to reduce risk of a hazard?
- Monitoring-volcanoes are monitored using a range of equipment such as seismometers
- Prediction-Monitoring of volcanoes now allows more accurate predictions of eruptions to be made but there is no way to predict earthquakes
- Protection- Many countries now practice earthquake drills and Evacuation and exclusion zones move people out of areas at risk. Earthquake resistant building design and sea walls are built.
- Planning-Hazard mapping and risk assessment are used to identify areas which are at greater risk and Stockpile of emergency supplies
Global Atmospheric Circulation Model
* definition
* overview
- The global atmospheric circulation can be described as a worldwide system of winds moving heat FROM the equator TO the poles to reach a balance in temperature
* 2.
