Hazardous Environments Flashcards
1
Q
Hazard
A
A hazard is an event which has the potential to cause harm to the environment, people or economy.
2
Q
Natural Hazard
A
A natural hazard is an event caused by environmental processes.
3
Q
A disaster
A
A disaster occurs when harm actually occurs to the environment, people or the economy.
4
Q
Natural hazards: categorized by their causes
A
**Tectonic/geological: **
* Earthquake
* Volcanic eruption
* Landslides
* Tsunami
**Climatic/Meteorological: **
* Storms
* Floods
* Droughts
* Tornadoes
Biological:
* Pests
* Diseases
5
Q
Natural Hazards
Ways they are categorised
A
Magnitude - the strength/power of the event
**Frequency **- how often the event occurs
Size - the area covered by the hazard
Duration - the time a hazard event lasts
Location - where a hazard event occurs
6
Q
Tropical Cyclones
A
- Tropical cyclones are rotating, low pressure systems.
- Known as hurricanes, cyclones and typhoons in different areas of the world.
Characteristics include: - Heavy rainfall
- High wind speeds (over 119 kmph)
- High waves and storm surges
*Rotating clouds surround a central, calm eye - The magnitude of tropical cyclones is measured on the Saffir-Simpson Scale from 1 to 5
- They develop in tropical regions between 5 degrees and 30degrees north and south of the equator
7
Q
Earthquakes
A
- A sudden, violent shaking of the ground.
- Earthquakes occur at all types of plate boundaries.
- Earthquakes are the result of pressure building when tectonic plates move.
- The epicentre is the point on the Earth’s surface directly above the focus
- The focus is the point at which the earthquake starts below the Earth’s surface.
- The magnitude of earthquakes is measured on either the Richter Scale or the Moment Magnitude Scale
- The damage caused by earthquakes is measured on the Mercalli Scale
8
Q
Volcanoes
A
- When magma erupts onto the Earth’s surface as lava.
- Most volcanoes occur at constructive (divergent) and destructive (convergent) plate boundaries.
- The majority of active volcanoes are located around the rim of the Pacific Ocean called the ‘Ring of Fire’
- Hotspots occur away from plate boundaries and are plumes/columns of magma which escape through the Earth’s crust.
- The magnitude of a volcanic eruption is measured on the Volcanic Explosivity Index (VEI)
9
Q
Causes of Tropical Cyclones
A
Tropical Cyclones require specific conditions to form:
* Warm Sea surface temperatures over 27°C
* Between 5° and 30° north and south of the equator
* Low wind shear
* A deep layer of humid air
* Low pressure areas
10
Q
Stages of Tropical cyclone formation
A
- Warm, moist air rapidly rises forming an area of** low pressure**.
- air then rises forming a continuous flow of rising air.
- As the air rises it **cools **and condenses. This releases heat energy which helps to power the tropical cyclone.
- Air at the top of the storm goes outwards away from the centre of the storm.
- The Coriolis force causes the rising air to spiral around the centre.
- Some of the air sinks in the middle of the storm forming the cloudless, calm eye.
- The tropical cyclone moves westwards from its source.
- When a tropical cyclone makes** landfall **or moves over an area of cold water it loses speed and temperature. Rainfall and winds decrease.
11
Q
Features of Tropical Cyclone
A
- Heavy rainfall
- High wind speeds (over 74kmph)
- Storm surges
- Calm eye
- Highest winds and heaviest rain in the wall of the eye.
- Diameter up to 800km
12
Q
Plate Boundaries
Constructive (Divergent)
A
- Plates are moving apart
- The Mid-Atlantic Ridge is an example. This is the North American and Eurasion plate in Iceland.
- Both volcanic eruptions and earthquakes can occur
13
Q
Plate Boundaries
Destructive (Convergent)
A
- Plates are moving together.
- The denser, heavier oceanic plate subducts under the lighter, less dense **continental **plate.
- Eg. Nazca plate and the South American plate
- Both volcanic eruptions and earthquakes occur
14
Q
Plate boundary
Collision
A
- Plates of similar density move towards each other
- Neither is dense enough to subduct so the land is pushed upwards.
- This process forms fold mountains eg. The Himalayas
- Earthquakes can occur
15
Q
Plate boundary
Conservative
A
- Plates move **past each other **in opposite directions or same direction at different speeds.
- eg. San Adreas Fault in California
- Earthquakes only occur here.
16
Q
Volcanoes at Constructive Boundaries
A
- constructive boundary > plates are moving away from each other.
- often occur under the sea/ocean.
- The lava escapes through the gap left as the plates move apart.
- The lava cools and hardens, forming a **new crust. **
- Here the lava tends to be runny and eruptions are less explosive.
- These types of eruption form shield volcanoes, which have gently sloping sides.
17
Q
Volcanoes at Destructive Boundaries
A
- destructive boundary > plates are moving towards each other.
- oceanic plate subducts under continental plate.
- In the subduction zone, the two plates come together, causing friction.
- Friction causes heat and the plate material melts, forming magma.
- The magma rises to the surface through cracks in the crust.
- The cooling lava and ash build up, forming a volcano.
- Here the lava tends to be sticky and produces explosive eruptions.
- form **composite or stratovolcanoes **
18
Q
Volcanoes at Hot spots
A
- At a hot spot, the tectonic plate passes over a plume of magma.
- The magma rises to the surface through cracks in the crust.
- As the tectonic plate moves slowly over the magma plume, a line of islands may form, e.g. Hawaii
19
Q
Volcano Primary and Secondary Hazards
A
**Primary(caused by the volcanic ruption itself): **
* Ash
* Pyroclastic flow
* Lava flow
* Gas emissions
* Volcanic bombs
**Secondary(happen as a result of the primary hazards): **
* Lahars
* Acidification
* Landslides
* Climate change
* Fires
* Floods
20
Q
Earthquakes and Plate boundaries
A
- Happen at all plate boundaries
- At a constructive plate boundary = earthquakes are weaker (plates are moving apart).
- At destructive, collision and conservative plate boundaries earthquakes = stronger
21
Q
Earthquakes Primary and secondary Hazards
A
**Primary: **
* Ground shaking
**Secondary: **
* Collapse of buildings and other structures
* Landslides
* Gas leaks
* Fires
* Mudflows
* Tsunami
22
Q
Earthquake sequence
A
The sequence of an earthquake is the same regardless of the boundary at which it happens:
1. As the tectonic plates move, they can get** stuck**.
2. Pressure builds as the plates continue to try to move.
3. Eventually, the plates jolt free and the pressure is released as energy.
4. The point at which the earthquake starts is the focus.
5. The epicentre is the point directly above the focus on the earth’s surface.
6. The energy passes through the Earth’s crust as waves which is the earthquake.
7. Earthquakes can happen as a result of human activity such as drilling into the crust or mining.
23
Q
Reasons for Living in Hazardous Regions
A
There are a number of reasons why people continue to live in these areas:
* A lack of education and information means that people are not aware of the risks.
* The advantages of living in the area outweigh the disadvantages - fertile soil, geothermal energy, access to water, trade, jobs, tourism.
* People are too poor to move away, they have little choice about where they live.
* People were born in an area and have friends/family there so do not want to move.
* If disasters don’t happen frequently people may believe that they are unlikely to be affected.
24
Q
Factors which Affect Vulnerablity
Economic
A
Wealth & level of development: the quality of buildings, healthcare, infrastructure all depend on the wealth of a country/area.
Insurance: People in poverty cannot afford insurance.
**Buildings: **Planning, controls, poverty, building styles and the quality of materials all affect the safety of buildings.
Technology: Wealthier countries will have more access to monitoring equipment so may get more warnings.
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Factors which affect vulnerability
| Social
**Population density:** more people in an area = higher the numbers of deaths/injuries. High population density also means buildings are likely to be more densely packed.
**Education:** people with a higher level of education are likely to be wealthier and be able to afford better-quality housing. Levels of education also affect how informed people are about the risks.
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Factors which affect vulnerability
| Physical
**Global location**: some areas experience more hazards because they are near plate boundaries or in tropical regions.
**Physical environment** : steep slopes can increase the chances of landslides, and coastal areas are more vulnerable to storm surges and tsunami.
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Short term impacts of Hazard events
* Damage to properties from high wind, heavy rain and storm surges, power cables and telephone lines.
* Impact on businesses, tourism, transport
* Landslides
* Deaths and injuries (decrease in quality of life)
* Crops destroyed > impacts farmers income > increasing food prices
* Habitat destruction
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Long term Impacts of Hazard events
* Rebuilding of homes, schools, infrastructure can take a long time.
* Cost of rebuilding affects the economy > increases unemployment
* Stricter building codes introduced
* Mental health problems (PTSD)
* Risk assessment and hazard mapping reviewed.
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Case Study: Impacts of Tropical Cyclones
| Haiyan (Philippines, Vietnam, Taiwan)
Date: November 2013
Magnitude: Cat 5
Highest wind speed: 315km/h
Storm surge: up to 6m
Rainfall: 282mm in 12hrs
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Case Study: Tropical Cyclone haiyan Impacts
**Short term: **
* 6400 deaths
* 4.1 mill homeless
* Roads blocked
* Electricity loss
* Airport in Tacloban damaged
* 1.1mill tonnes of crops destroyed
* 14mill people affected
**Long term impacts: **
* Cost US$5.8 billion
* Build back better is working slowly
* No build zones along coastlines
* Storm surge warning system
* Mangroves replanted
* Tropical storm shelters built inland
31
Case Study: Impact of Volcanoes
| Mount Merapi (Java, Indonesia)
Date: 25 Oct - 30th Nov 2010
Magnitude: VEI 4
Plate boundary: Destructive Indo-Australian plate subducts below the Eurasian plate
Type of Volcano - Stratovolcano/composite
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Case Study: Mount Merapi impacts
**Short term: **
* 353 deaths
* 577 injuries
* Pyroclastic flow travelled 3km
* Volcanic ash fell up to 480km away
* Roads blocked
* 350,000 people evacuated
* Lahars
* Decrease in tourism income
**Long term impacts: **
* Hazard map updated
* Over 2,500 residents moved to new homes
* Impoved monitoring
* increased education to inform
* Dams built
* Soils will be more fertile due to minerals in ash.
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Warning & Evacuation
* Many different methods of monitoring are being used to help research possible. **Prediction methods:**
* Tiltmeters - which monitors ground changes
* Clusters of small earthquakes
* Changes in radon gas emissions
* Changes in animal behaviour
* Remote sensing of ground movement using satellites
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Building Design
* In **developed** countries building design and engineering are commonly used to reduce the impact of earthquakes.
* Building regulations require new buildings to include earthquake-resistant features:
* Shutters on windows prevent falling glass
* Cross-bracing of steel frames
* Foundations sunk deep into the bedrock
* Frames which sway with the earthquake tremors
* Rubber shock absorbers to reduce tremors moving through the building
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Land Use planning
* Mapping of areas most at risk from earthquakes.
* Planning can ensure that valuable services such as the fire service and hospitals are not built in high-risk areas.
* Densely populated housing can be located away from high-risk areas.
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Drills & Education
* In many countries, earthquake drills are regularly carried out.
* The drills help people to prepare for what to do in an earthquake to protect themselves.
* Education about how to prepare homes means that people are less likely to be injured by falling objects and furniture.
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Remote Sensing & GIS
* **Remote sensing** of the Earth's surface by satellites provides data about changes in ground movement.
* Geographic Information Systems (GIS) provides layers of data such as:
* vulnerable areas
* land use
* infrastructure eg. roads
* GIS data is then used to assist with land use planning.
38
Case Study: Earthquake preparation
| Nepal - A developing country
*Preparations before the Earthquake: *
* Funding to schools for earthquake drills
* Allocations to areas to be shelters
* Improved the **national building code**
* The government set up a **National Strategy for Disaster Risk Managment. **
*Issues with the preparations: *
* There are many different languages in Nepal and so educating and drills was difficult.
* There arent enough supplies to equip shelters.
* Due to political instability, the mangement groups were not as effective as they should be.
39
Case Study: Earthquake prepartation
| Japan - A developed country
**Preparations before the 2011 earthquake: **
* Earthquake drills practiced regularly
* Households are encouraged to have a emergency bag prepared
* Many buildings are earthquake-resistant
* Trains and Nuclear stations automatically stop
* Sea walls built along the coast
* Tsunami warning system - issued via; phone, tv, sirens
*Issues with preparations: *
* People knew what to do for an earthquake but not a tsunami
* many buildings survived the earthquake but not the tsunami
* the tsunami overtopped the sea walls
* People ignored the tsunami warning (thought they were protected)
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Short-term response & Relief
* The emergency response are the actions taken immediately after a hazard event eg. a earthquake:
* Searching collapsed buildings to rescue people who are trapped.
* Providing medical assistance
* Distribution of food and water
* Ensuring that people have shelter
* Clearing rubble and other debris
* This response has to be coordinated as many NGOs and government organisations, including the armed forces, may be involved.
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Case Study: Short-term response
| Nepal - a developing country
* Short-term response criticised for being too slow:
* The epicentre was not reached by rescue workers for 24 hours.
* Evacuations of the critically wounded took 5 days.
* Over **US$1 billion** in international aid from India and China
* 3 Chinook helicopters; 100 search and rescue; medical workers
* Use of **GIS** to coordinate the response
* Many **NGOs** sent aid workers, food, water and medical supplies
* Tent cities in Kathmandu provided shelter for people made homeless
42
Case Study: Short-term response
| Japan - a developed country
* Self Defence Forces sent in immediately to organise food, water, shelter and medicines.
* Within 48 hours a member of parliament was designated to coordinate the relief effort.
* UK sent search and rescue teams
* NGOs provided shelter, food, water and medical aid
* A tsunami warning was issued giving people 20 minutes to get to safety
* Temporary shelters were set up in schools and other public buildings
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Long term planning
* Occurs after the hazard event
* Looks back at the event and evaluate what could be done to reduce the impact of any future hazard events:
* Was emergency aid distributed effectively
* Are there areas which are at particular risk
* Could warning systems be improved
* Are people educated about the risks and do they know what to do during the event to protect themselves?
* Can building codes and planning be improved to reduce the number of buildings which collapse
* Risk assessment and hazard mapping are both part of the long-term planning process
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Risk Assessment
* **Risk** is the probability that a hazard event will have harmful consequences.
* The more **vulnerable** a population is the greater the risk that a hazard event will cause deaths, injuries, damage to buildings and impact the economy.
* The number of deaths from earthquakes has increased due to Increasing populations and urban areas means that more people are living in areas at risk.
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Hazard mapping and GIS
* Maps the areas where earthquakes are most likely to occur.
* Enables planning of where important services and infrastructure should be located - land use zoning.
* Identifies correlation between risk and vulnerability
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Rebuilding Programmes
* In an earthquake, it is the collapsing buildings which cause the most injuries and deaths.
* Reducing the damage to buildings can be achieved by:
* Reducing the number of buildings in high risk areas
* Building earthquake resistant buildings
* Large scale rebuilding is often required after an earthquake event
* Existing buildings and structures, such as bridges, can be retrofitted to make them safer in future events
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Case Study: Long Term planning
| Nepal - a deloping country
* The Asian Development Bank provided US$200 million for rehabilitation.
* A government task force was created to plan and deal with future earthquakes.
* Improved building code with increased awareness of the code within communities.
* Training courses to ensure that new buildings are earthquake resistance.
* Increased education and earthquake drills.
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Case Study: Long term planning
| Japan - a developed country
* Building Back Better - considers building codes, town planning and infrastructure
* New tsunami walls have been constructed 25-30m high
* A new US$31 million warning system launched in 2013
*Developed countries often have less to change in their long term planning because their preparation for the hazard is better. However, the costs of any disaster are often greater than in a developing country. This because the buildings, roads and infrastructure that is damaged are more expensive.*
