GCSE Geography: The Challenge of Natural Hazards

paper 1

what period are we in

the quaternary period

evidence for climate change (4)

• air and sea temperatures rising as scientists have a record of it for 100yrs ago (instrumentzal temperature record)

• using deep marine sediment cores and ice cores

• studying air bubbles

• composition of water

current evidence for climate change (3)

• sea levels rise: risen by 21-24cm since 1800 due to higher temps which causes glaciers and ice sheets to melt and this freshwater flows into the sea. water also expands when it gets warmer so as the earth warms, the whole sea is expanding and rising

• melting of glaciers and icesheets. sea ice is thinning and not extending as far (by 65% since 1975 in the arctic ocean)

• changes in ecological pattern: bird migration, plant flowering pattern and breeding seasons have been shifting

natural causes of climate change (5)

• orbital changes: the orbit of the earth changes from a near perfect circle to an ellipse (oval) which affects how intense the sun’s rays hits the earth, one cycle takes 100,000 years

• the tilt of the earth’s axis changes from 21.5 degrees and 24.5 degrees which affects the contrast between summer and winter seasons. the change between 21.5 and 24.5 takes around 41,000 years

• precession describes the wobble of the earth’s axis which affects the length of days, a full cycle takes over 20,000 years

• sun spots: 11yr cycle where the amount of sunspots on the sun surface varies from minimum then maximum then minimum. when minimum it reduces the solar output.

• volcanic activity: the ash and the gas that erupted into the atmosphere caues a cooling effect causing a reduction in surface temperature (volcanic winter). large amounts of volcanic ash stay in atmosphere and block out the sun (short term cooling). Volcanic eruptions emit gases which react to form aerosols which reflect solar radiation the effect can last several years

Human causes of climate change (3)

• burning of fossil fuels releasing greenhouse gases

• different farming methods which release methane

• deforestation which reduces co2 taken up by trees

what is the greenhouse effect

when greenhouse gases (water vapour, carbon dioxide, methane and nitrous oxides) trap energy from the sun in the earth’s atmosphere which heats the earth

what happens when the sun shines on the earth (4)

• solar radiation from the sun (short wave radiation) travels to our earth and heats up the earth’s surface

• the earth gives off heat (long wave radiation) when it cools

• some of this heat leaves our atmosphere and goes into space

• some of this heat is trapped by greenhouse gases which keeps our earth warm

what % of global warming is caused by methane emissions

25% even though there is much less methane than CO2 in the atmosphere

how much methane do cows produce everyday

250-500 litres

how much will avg global temp increase by at the end of the century

4 degrees

what does mitigate mean and how can we mitigate climate change? (4)

• reducing the causes of climate change so that climate change slows or even stops such as reducing greenhouse emissions

• alternate sources of energy (nuclear power, biomass, hydroelectric power, geothermal, solar,wind and tidal power)

• carbon capture: capturing and storing it underground in resevoirs. can reduce up to 90% of co2 emissions from industry

• planting trees: trees release moisture into the atmosphere which forms clouds to reflect solar radiation (albedo affect)

how much of the uk has renewable energy

1/3

international agreements

manage climate change by setting goals to recuce their emissions

• paris climate agreement - 2015

paris climate agreement

• 2015

• 195 countries agreed to ensure warming is kept below 2 degrees by the end of the century

• strengthen the ability of countries to deal with the impacts of climate change

adaptation meaning and how we adapt to climate change

• responding to climate change by coming up with ways to live and cope with the effects by reducing the risks assosciated with climate change like building flood defenses to manage sea levels

• introducing irrigation systems (giving crops controlled amount of water creating new strains of crops that produce higher yields)

• new technology such as some farms in sudan have air conditioned rooms for cows

• building dams and resevoirs to store water for the population

• educating people to not waste water and food

• sea levels are expected to rise from 26-82cm by 2100

himalayas water management

they depend on meltwater but now the glaciers are melting quicker so in the future the region may not have any resources of meltwater left so they have to create artificial glaciers. meltwater is collected and sprayed onto the structure so it freezes and can be stored when needed

managing sea levels rise (4)

• building flood defenses such as sea walls or use sandbags to stop water

• houses built on stilts and redistributing populations to other areas areas

• constructing areas that are high above sea level

• restoration of mangroves which are shrubs that can trap sediment and slow water flows with their thick roots

what is a natural hazard

natural occuring event that is a threat that can negatively affect (threat) the population

nepal (5)

• april 2015

• killed 9000 people

• 7.8 earthquake

• 19k injured

• ADB provided 3 mil to nepal for immediate relief efforts

what is an event

something that doesnt affect the population

geological hazards (4)

• volcanoes

• earthquakes

• landslides

• mudflows

hydrological hazards (1)

• flooding

atmospheric hazards (3)

• tropical storms

• tornadoes

• droughts

what is a hazard risk

probability that a natural hazard will actually affect a population

what factors affect hazard risk (5)

• urbanisation (housing can collapse)

• population growth

• wealth

• land use (floodplains are very fertile)

• climate change

layers of the earth outside to inside (4)

• crust

• mantle

• outer core

• inner core

comparing continental crust and oceanic crust (4)

• continental is older

• less dense

• thick

• oceanic made from basalt, continental made from granit

convectional currents (6)

• core heats up the magma in the mantle

• hot magma is less dense so it rises upwards

• when it reaches the top it cools

• so it becomes more dense and sinks back down to the bottom

• it is heated up again and the cycle continue

• the plates ontop are pushed and pulled by convectional currents in the magma

1. north american plate

2. pacific plate

3. nazca plate

4. south american

5. cocos

6. caribbean

7. african

8. eurasian

9. arabian

10. indian

11. australian

12. philippine

13. antarctic

where is the ring of fire

pacific ocean

where does tectonic hazards occur the most

west of north america and south america or in the atlantic ocean between africa and south america

where else can volcanoes occur other than on land

• in the pacific ocean (hawaii)

• magma breaks through the middle of the plate and travels up to the surface (the hotspot)

constructive plate (4)

• move away from eachother

• magma rises and lava pours out the surface

• volcanoes forms and form shield volcanoes

• this can happen on continental or oceanic crust

what is it called when new land s formed on the ocean floor

sea floor spreading

how do islands form

when lava cools it forms rock, when the rock builds up it forms islands

destructive plate (8)

• when the plates move towards eachother

• happens with two oceanic ( islands form e.g. mariana trench) or two continental plates (neither can subduct and instead the crust crumpled upwards by pressure building which creates fold mountains (himalayas formed by eurasian and indian plate)

• oceanic subducts under the continental crust as its denser

• the plate that is subducting leaves a deep ocean trench

• friction between the two plates causes strong deep earthquakes

• the ceanic crust is melted as it is pulled deeper into the mantle, creating magma

• this magma causes pressure to build up under the crust

• eventually the magma pushes out through weaknesses in the crust, creating composite volcanoes

conservative plate margin (4)

• parallel plates move in different directions or at different speeds to eachother

• friction builds between the plates over many years and eventually the pressure gets to large that he plates move in a sudden jolt releasing lots of energy which sends vibrations through the ground (an earthquake)

• on oceanic crust, fault lines occur where the ground is cracked by the movement

• there are no volcanoes on conservative as no magma is being generated

primary effects meaning for tectonic hazards

• effects directly caused by natural hazard itself

secondary effects meaning for tectonic hazards

effects that are a result of primary effects

effects of tectonic hazards (4)

• spread of disease due to poor hygeine, contaminated water

• intense shaking of ground (avalanche, tsunamis, landslides)

• infrastructure and homes destroyed

• people killed from damaged buildings and infrastructure or by hot ash and gas frm volcano

immediate responses (3)

• searching for people trapped under rubble

• clearing roads to gain access to isolated areas to allow rescue services

• setting up shelters

long term responses (3)

• reconstructing services and buildings

• insurance payouts

• making infastructure safer

why do people live in hazadous areas (8)

• lots of nutrients in volcanic material (most fertile), making soil fertile

• agriculture is many people who live in the area’s main source of income

• tourism, the blue lagoon makes £120 million per year heated by geothermal activity

• warning systems have been developed like seismic activity and buldging of volcano.

• better building designs such as carbon fibre curtain to minimise effects of shaking

• infrequency of tectonic events (mount vesuvius has not erupted since 1944)

• culture

• poverty and education

how many people live in hazadous areas

2.7 billion and 400 million live near one of the 220 most dangerous volcanoes

types of hazard management (4)

• monitoring: detecting and recording physical changes and warning signs

• predicting: monitorying as well as historical trends to predict when a tectonic event may occur

• protecting: increasing resistance of a population by designing things which will withstand tectonic hazards

• planning: having systems in place such as evacuation routes so people are prepared

how to monitor earthquales

• seismologists monitor small tremors in the ground

• ground deformation

• change in groundwater

• there is no technology to indicate with certainty that an earthquake is coming

how to monitor volcanoes

• ground deformation: buldges in the ground can indicate movement of magma

• gases: sulfurous gases can indicate rising magma

• changes in heat: temperature differences also indicate processes beneath the surface

• vibrations underground: small earthquakes can indicate changes underground

• smaller eruptions of smoke and steam: indication of a larger eruption coming

what can be used to monitor changes in volcanoes

• satellites and sensors

Predicting

you can predict tectonic hazards by:

• small warning signs

• historical trends can give indication of the time frame when another similar event may occur, or even when an event is overdude

• model the data on computers to more accurately predict hazadous events

predicting earthquakes

• caused by buildup on energy due to friction of two plates

• if earthquake hasn’t happened for a while scientists predict the next earthquake will be bigger because energy has been building up for longer

How to protect against volcanic eruptions

• Concrete blocks and explosives are sometimes used to divert or slow lava flows, but this is only to redirect the flow from one place to another, such as away from densely populated areas

How to protect against earthquakes

• buildings can be constructed to be resistant to intense shaking

• foundations can be built deeper into the ground and reinforced to reduce risk of collapsion

• rubber shock absorbers in foundations to absorb earth tremors

• steel frames that can sway during earth movements

• open areas outside of the buildings where people can assemble during an evacuation

Planning

• hazard mapping: dividing hazadous areas into different levels of ris, and changing the land according

• important buildings such as hospitals and power plants can be built away from high risk areas and it helps decide who should be evacuated when the event happens

• evacuation plans and safety protocols can also be developed so the population knows what to do: “drop, cover, hold on”