IGCSE edexcel Geography ( Hazardous Environments)

What are hazardous environments?

An environment that is prone to hazards & natural disasters due to location

Why are some places more hazardous than others?

Experience more than one type of natural hazard event
Experience natural hazards more frequently than others
Some places hazards are stronger and more destructive
Some places are better able to cope with damaging impacts

What are the four classified categories of a natural hazard?

Geological,Climatic,Biological,Technological

Name a few examples of a geological hazard:

Earthquakes,Volcanic eruptions, Landslides

Name a few examples of a Climatic hazard:

Floods, Droughts, Storms

Name a few examples of a Biological hazard:

Fires
Pests
Diseases

Name a few examples of a Technological hazard:

Nuclear explosion
Transport accidents
Pollution

How does a Tropical Cyclone form? (6)

Starts when high temperatures cause air to rise from the surface of the sea

Warm, moist air is forced to rise/ wind begins to gust
Air spirals upwards

Wind speed increases
Cooling & condensation produce cumulonimbus clouds with thunder and torrential rain

the Eye of the storm- period of calm where pressure is low and temperature starts to rise

Onslaught begins again with hurricane-force winds & torrential rain. Temperature begins to drop but pressure rises

End of hurricane- Temperature and pressure rises and rain decreases, some sunny intervals

What are the conditions needed to create a cyclone?

A deep layer of humid, warm (+27degrees ) & unstable air
A supply of energy

What are Plate tectonics?

The crust of the earth is made up of a number tectonic plates, rigid blocks that make up the surface of the Earth.

These plates move over the surface of the globe, their movements create four different types of plate margin

What is a plate margin?

The boundary where two plates meet

What are the four types of plate margins?

Constructive Plate Margin
Destructive plate margin
Collision plate margin
Conservative plate margin

What is subduction?

The edge of one plate is being destroyed as it plunges beneath the other plate that is meeting it head on

What is a constructive plate margin?

When two plates are moving apart from each other, constructive or divergent boundary
Magma rises through crust to fill the gap & create new crust through volcanoes

*mid atlantic ridge in the atlantic ocean

What is a destructive plate margin?

When two plates are moving towards each other, margin between them called destructive or convergent plate boundary
friction causes earthquakes
*nazca plate & south american plate

what is a collision plate?

Where two plates meet head & are equal thickness & strength
pushes land upwards forming fold mountains, such as himalayas
earthquakes can be created by the pressure

What is a conservative plate margin?

Two plates sliding past each other. The friction between the two plates can create earthquakes

How are volcanoes formed? (4)

Formed through tectonic activity
Two plates crash or separate, constructive plate margin causing pressure & gases to build in the magma chamber

Pressure becomes too much and magma is forced up & out the vent

Magma explodes through crater causing rock, gas & air to be thrown out

Lava flows down the sides of volcano

Overtime this will cool forming new layers on top of the volcano

What is the mid atlantic ridge?

A tear in the earth that magma comes through

What is the ring of fire?

An area of volcanoes & earthquakes that is found in the pacific

Explain the formation of earthquakes: (6)

Formed through tectonic activity
Two plates crash or slip past each other, conservative plate margin.
This movement towards or past each other creates pressure between the two plates. This is where the two plates meet is called the focus

The pressure releases when one plate slips past or under the other. This releases energy called Seismic Waves which travel to the surface above

The point on the surface of the earth where the earthquake is the strongest is called the epicentre which is directly above the focus

The worst damage occurs where the focus is closest to the surface and there are soft rocks

Shock waves "liquify" soft rock removing its load bearing capabilities causing it to behave like liquid and so buildings collapse

Why are earthquakes so destructive?

Shockwaves cause the ground to shake for which can cause buildings to be unsteady and sway

Aftershocks which are shockwaves that are felt in hours & days after the initial earthquake are the most dangerous because they continue to shake the ground resulting in unsteady buildings, damaged pipelines to break (releasing gas which can cause fires), transport lines to be cut off & people can die

How do tsunamis form?

A tidal wave or tsunami is the result of tectonic activity beneath the ocean

When plates collide or separate, destructive plate margin, under the ocean, the epicentre will be located on the sea floor

This will generate large waves to build up because of the shaking movement.

Send waves towards land causing huge destruction

How do we measure a volcanic eruption?

Volcanic Explosivity Index (VEI)
-Measures the intensity of volcanic eruption from a scale of 1-8

What is the VEI?

-Explosivity measure in terms of the volume of the ash ejected from the crater & the height the ash reaches the atmosphere
-Only suited to assess one type of eruption

What is the Richter scale?

Measures an earthquakes strength according to the amount of energy released during an event
Energy measured by a seismograph

What does the Mercalli scale measure?

Intensity of an earthquake
based on what people experience & the amount of damage done

What is the moment magnitude scale? (MMM)

Measures the energy released by the earthquake
Assessment of energy is based on the amount of rock movement along a fault or fracture & the area (size) of the fault or fracture

What other factors are involved in damage and destruction?

Size of area affected
Density of the population
Preparation of emergency services, building compliance
Time period of the event
How well educated the people are about an event, preparation
Ability of the country to deal with an event technologically and financially

What are primary impacts?

immediate effects of a tectonic activity such as
Collapsed buildings
Injury/Death
Broken pipes
Damaged electrical lines

What are secondary Impacts?

effects that happen later on

Name the secondary impact of earthquakes:

Tsunamis
aftershocks
Fires due to ruptured gas mains

Name the secondary impacts of volcanoes:

Lahars- created by the mixing of hot volcanic ash & mud with rainwater
Fire started by lava
Psychological effect on people

What is a Pyroclastic flow?

A devastating explosion of extremely hot gas, ash & rocks during a period of explosive volcanic activity; downslope flow of this mixture is very fast and capable of reaching speeds up to 200 kph

What is a wind shear?

change in wind speed or direction over a short distance

Why do people live in hazardous areas?

A lack of education & information may mean that people wont take the issue seriously & not aware of the risks

People may be aware of the risks but continue to live there anyway maybe because of tradition & because their ancestors lived there (connection to that area).

Some families are poor so they cannot afford to move away e.g Farmers depend on fertile land provided by volcanoes

Perhaps the biggest factor is areas of high population density e.g Tokyo. It would take alot of time & money to move a large amount of people away therefore they adapt too these conditions.

What are some benefits to High risk areas?

Minerals: Volcanoes bring valuable mineral resources to the surface. These include diamonds, gold & copper

Fertile soils: volcanic ash often contains minerals that enrich the soil. Fine dust is quickly mixed into the soil & acts as a fertiliser

Geothermal energy: Water running through the Earth's crust is heated by volcanic rock at or near a plate margin. This hot water emerges as hot springs which can be used to heat homes, businesses, factories.

Tourism: volcanoes interest many people & attract tourism. Hundreds of thousands of tourists visit Mt.Vesuvius in italy each year

How do we monitor Tropical cyclones?

Saffir simpson numerical scale used to measure the strength of a cyclone based on wind speed, air pressure, storm surges and typical damage. The cyclone is categorised into 5 categories 1 being the weakest and 5 being the strongest.

What are the four different impacts of tropical cyclones?

Physical: The damage to property caused by high winds, heavy rainfall and storm surges along coastlines.

Social: The number of people killed or injured, the disruption of communities and their normal way of life, any decline in quality of life.

Economic: This disruption & destruction of businesses, transport lines and services

Environmental: Landslides, soil erosion, damage to ecosystems & flooding can change the environment of an area.

What are the primary impacts and secondary impacts of a tropical cyclone?

Primary impacts of a cyclone are the direct result of high winds, torrential flooding and storm surges

Secondary impacts are more varied. They can include the costs of repairing the damage, spread of water borne disease, loss of homes, loss of personal belongings and repair transport lines

What are some factors we should think about doing risk assessment?

Its distribution: where will it occur on the planet

Its frequency: How often does something like this occur in a particular region. In this case of a tropical cyclone, it is every and normally in Autumns

Its scale: does the event vary in degree of hazard and impact

Its predictability: does the hazard always behave in the same way? In this case of cyclones there is normally a sequence of events that occur.

Explain how the methods of monitoring weather conditions have changed: (6)

Before they would use wind vanes and thermometers but due to advancements in technology we now have:

Weather stations --> A global network of weather stations track the movement of tropical storms. Once all the information about pressure, temperature, humidity, rain and wind is collected; it can be used to predict what type of weather will be experienced.

Weather Satellites --> These show cloud formations, tropical cyclones and other global weather systems that might occur around the planet.

Radar --> This measures reflected sound waves. When sound waves are broadcast from a radar mast and encounter an object such as a rain cloud, the provide information about its direction and movement.

What are some methods of preparation?

Plan evacuation systems, educate families on how to act when a hazard is occurring

Stock up on food, water, electrical, first aid kits and medical supplies

Train and prepare emergency squads and response teams

Install warning systems

Screw furniture down, build stronger infrastructure

Flood defences

What are the different types of emergency teams that should be involved during emergency responses?

Releasing people and bodies trapped in collapsed buildings

Using lift gear to clear away rubble

Restoring services

Providing medical help and counselling

Organising the distribution of emergency rations

Setting up shelters

Providing transport for emergency supplies

What is appraisal?

This is the inquest into what happened , looking back at the disaster and assessing how well organised it was.
The appraisals considers if anything more could have been done

How can we prepare buildings better to reduce the impact of an earthquake? (4)

1. Building quake-proof buildings, stronger infrastructure using resistant materials

2. Automatic shut off systems to shut off water systems to prevent leakages. Use flexible material on drain pipes

3. Install warning systems in the building, sound alarms

4. Remote sensing and GIS technology to monitor tectonic activity and earthquake movement