HAZARDS

what is the definition of a hazard

a threat which has the potential to cause injury, loss of life, damage to property, socio-economic disruption and environmental degradation  

in what ways can hazards vary

• nature

• magnitude

• frequency

• geographical location

• scale of impact

what is the nature of a hazard

type- e.g. volcanic

what is the magnitude of a hazard

size of the power of a hazard

what is the frequency of a hazard

how often it occurs

what is the scale of impact of a hazard

how many people it affects/ the area of land it affects

what are the classifications of hazards

• geophysical

• atmospheric

• hydrological

• biological

give examples of geophysical hazards

• volcanic

• earthquake

• avalanche

give examples of atmospheric hazards

• dust storm

• cold wave

• heat wave

• tropical storm

• drought

• wildfire

give an example of hydrological hazards

flooding

give examples of biological hazards

• insect infestation

• infectious disease

what is risk

the probability of a hazard even occurring and creating loss of lives and livelihoods

what are the 3 types of risk

• hazards to people

• hazards to goods

• hazards to environment

give examples of hazards to people

• death/injury/illness

• losing housing/possessions

give examples of hazards to goods

material possessions→ e.g. food, appliances, technology, transport

give examples of hazards to the environment

pollution→ e.g. air, water, soil, ect.

describe drought

• rainfall of 50% less than the 3 month median

• frequently includes extreme heat, wildfires and secondary hazard of famine

• 40% of the worlds land surface, containing 70% of the population and 70% of the agricultural production is exposed to drought.

describe floods

• coastal, river and flash flooding occurs in over 1/3 of the world’s land areas

• affects 82% of the worlds population

• 10% of the land’s surface is very flood prone and contains 40% of the world’s people

describe storms

• cyclones can include temperate storms and tornadoes

• concentration in tropical belts, especially coastal areas

• covers 6.7% of the world’s land area but 24% of the world’s population

• areas often developed and contain much infrastructure and GDP

describe landslides

• including snow avalanches

• affects 5% of the population

• largely in mountainous areas

• many are secondary hazards from earthquakes, floods and tsunamis

describe earthquakes

• 7.5% of the world’s total land area containing 20% of the pop. is earthquake prone

• distribution of earthquakes concentrated along mobile plate boundaries

describe volcanic hazards

• spatially concentrated

• affects only 0.5% of the worlds land surface

• associated with mobile plate boundaries or hotspots

describe large tsunamis

• associated with earthquakes and only affect coastal areas

• e.g. hawaii and indonesia

why do people continue to live in areas prone to hazards

• cheaper housing

• some people wouldn’t be able to move due to finances

• family ties→ e.g. family living nearby

• people may have adapted to overcome hazards- e.g. earthquake proof buildings

• fertile soils

what is vulnerability

• the conditions determined by physical, social, economic and environmental factors or processes which increase the susceptibility of a community to the impact of hazards

which factors increase vulnerability

• population increase

• poor infrastructure

• proximity to hazard

• lack of planning/education

• aging population

• reliance on power

• environmental degradation

which factors decrease vulnerability

• insurance policies

• adapted infrastructure

• education and planning

• scientific understanding

how is risk measured?

what are the most effective ways to insure accurate perception

• experience

• education

describe perception in hazards with low frequencys

• earthquake in the High Atlas Mountains of Morocco- September 8th 2023

• caused nearly 3000 deaths→ largely due to unprepared infrastructure with strong seismic shaking

• little education and experience with earthquakes- low accuracy in perception

• low preparation

why is education the most reliable way in hazards

• reduces the risk of misinformation and a false sense of security

• education can be tailored to different situations and communities

• education is long-term

• education can be constantly updates

give examples of education in hazards

• visit disaster prevention centres (simulations of what would happen and how to deal with them

• japan has disaster prevention drills once a year where the whole country is involved

describe how socio-economic status influences hazard perception

• wealthier people have better constructed houses

• access to internet

• security could lead to overconfidence

• can afford the latest gear and escape plans

describe how level of education influences hazard perception

• higher education means more understanding of the risk and how to dampen effects

• more education= higher accuracy of perception of the hazard

describe how occupation/employment status influences hazard perception

• income level (socio-economic status)

• repeated drills and training of how to deal with it

how does religion/culture influence hazard perception

• fatalism→ believe god intended a disaster to happen

• leads to low level of perception

describe how family and marital status influence hazard perception

• married people or ppl with families are more likely to be aware of risk

• responsibility

• support networks

• financial considerations (children and elderly)

describe how past experience influences hazard perception

• high accuracy of perception of hazard due to first hand experience

• will understand extent of danger, and how to learn from past mistakes

how do values, personality and expectation impact hazard perception

• culture, religion

• personality of indifference

what are the different approaches to perception

• fatalism

• Domination

• adaption

• fear

describe the fatalism approach to perception

• acceptance

• people remain where they are

• acts of god

describe the domination approach to perception

• suggests hazards are predictable and can be better understood by scientific research

describe the adaption approach to perception

• hazards are influenced by natural and human events, magnitude and frequency can be estimated based on experience and economic and technological circumstances of the area

describe the fear approach to perception

• people feel so vulnerable that they can no longer face living there and they move away

what is stage one in the park model

• normality

• preparation and mitigation

• before the disaster occurs

describe stage 2 of the park model

• hazardous event

• hazard occurs with immediate damage

• relief- takes hours to days

describe stage 3 of the park model

• deterioration

• search and rescue

• short term relief and emergency services

• hours to days

describe stage 4 of the park model

• relief and rehabilitation

• deterioration

• modify the loss- e.g. aid and temporary housing and services

• days to weeks

describe stage 5 of the park model

• nature of recovery related to the need to restore normality and reduce vulnerability

• improving after the hazard

• weeks to years

• improvement or return to normality

what is the hazard management cycle

• cyclical structure

• more simplified version of the park model

• specific examples of events that will take place

• no indication of a time period

describe the pre-disaster on the hazard management cycle

• preparing for the hazard

• risk assessment

• prevention

• making people aware

describe the response on the hazard management cycle

• Warning and evacuation 

• Immediate assistance to save people-> e.g. first aid and hospitals  

• Assessing damage 

• Food and water supplies 

• Media focus-> lots at first and decreases over time, showing recognition.  

describe the post-disaster on the hazard management cycle

• reconstructing/restoration/relocation

• long term international aid

• economic recovery

• mitigation and prevention

what are the similarities between the hazard management cycle and the park model

• pre-disaster, followed by disaster, then recovery, then post disaster

• both give examples of what happens at each stage

• clear points where the hazard physically hits

what are the differences between the hazard management cycle and the park model

• pm indicates time periods, hmc doesn’t

• hmc shows media coverage

• pm shows quality of life

• pm has more info

• pm doesn’t show the state of the country before the hazard hits

what are the weaknesses of the hazard management cycle

• reductionist- actions may not always occur in the order shown on the model

• shows no indication of time or quality of life- decreases predictive quality

what are the weaknesses of the park model

• reductionist- actions may not always occur in the order represented in the model

• time periods dont take into account wealth of the area or magnitude of the hazard

what are the strengths of the park model

• shows time frames

• has a curve to show quality of life

• clear strategies for governments to implement at each stage

• can be modelled for any hazard or emergency

what are the strengths of the hazard management cycle

• can be modelled for any hazard or emergency

• shows media involvement

• clear strategies for governments

• cyclical- constantly ongoing

describe the core of the earth

• thick dense rock- iron and nickel alloys

• divided into solid inner core and molten outer core

• 5000 degrees celsius

• heat is produced from: primordial heat from earths formation, radiogenic heat from radioactive decay of isotopes

describe the mantle of the earth

• made of molten and semi-molten rocks

• contains silicon and oxygen

• widest layer of the earth- 2900km

describe the upper mantle

• rigid layer above the asthenosphere which with the crust makes up the lithosphere

• the asthenophere- plastic type layer which moves slowely under high pressure and carries the lithosphere

describe the lower mantle

• hotter and denser than the upper mantle

• intense pressure at depth keeps the lower mantle solid

describe the crust of the earth

• most abundant elements= silicon, oxygen, aluminium, potassium and sodium

• lighter than other layers

• oceanic and continental

• oceanic is thinner and more dense

describe the lithosphere

• consists of crust and upper mantle

• has 7 main plates with some smaller ones

• coolest and most rigid part of the earth

describe the asthenosphere

• lies beneath the lithosphere it is semi molten

• plates can move

• 700km deep

who created the theory of continental drift

• Alfred Wegener

how was the theory of continental drift discovered

• found identical plants and animals on the opposite side of the atlantic

• close fit between the coastline of Africa and South America

• `Wegener couldn’t explain why the plates moved

• first continent of Pangaea

how do we know what the earth is made of

• geographic surveys: seismic, gravity, magnetics, electrical

• fieldwork

• boreholes

• mines

why is the continental crust permanent and does not sink

• oceanic crust is more dense so gets subducted

• continental crust does not melt due to not being subducted- therefore permanent

why is the oceanic crust not permanent

• more dense

• gets subducted

• melts when it reaches further down in the crust due to high temperatures

• reformed at divergent plate boundaries

if new oceanic plates are being formed where plates move apart, why doesn’t this mean the earth is expanding

• the rate at which new crust is being created must be equal to the rate of crustal destruction

• state of dynamic equilibrium

• so change is occurring but the overall balance remains the same

what is vulcanicity

• the process through which gases and molten rock are either extruded on the earth’s surface or intruded into the earth’s crust

• clearly linked to the existence of plate boundaries

what is seismicity

• the geographic and historical distribution of earthquakes

• distribution is closely associated with plate boundaries

what land forms are associated with plate movement

• young fold mountains

• rift valleys

• ocean ridges

• deep sea trenches

• island arcs

• volcanoes

describe the distribution of magma plumes

• deep plumes are concentrated more towards the equator and are in the ocean

• close to plate boundaries

• not a distinct obvious pattern

what is a hotspot

• a stationary plume of magma

• rises from deep within the earth

• the tectonic plates move over the stationary hotspots which leads to the formation of a chain of volcanoes

what is a volcanic eruption

• when a volcano gives of quantities of lava, ash or volcanic gas

what is a dormant volcano

• not erupted for 10,000 years but it is expected to erupt again

what is an extinct volcano

• hasn’t erupted for 25,000 years

• not expected to ever erupt again

describe how volcanoes are built

• often of divergent or convergent plate boundaries

• most commonly a conical hill or a mountain that is built around a vent

• built by the accumulation of their own eruptive products such as lava, bombs and tephra

where are most volcanoes concentrated

• the pacific ring of fire

• 40,000 km long

how is magma produced

• when the mantle is rising and it forces the crust to sink and melt under oceanic trenches

why are some volcanoes located in the centre of tectonic plates

• hotspots

• along rift valley

what is the volcanic explosivity index

• VEI

• every time you go up 1 magnitude the strength increases by x10

• logarithmic scale

describe VEI 0 eruptions

usually quiet, effusive eruptions of lava

give an example of a VEI 0 eruption

• mount erebus

• southernmost active volcano on Antarcticas Ross island

• frequent small eruptions

• last eruption was in 2020

describe a VEI 1-3 eruption

• progressively more violent explosive eruptions capable of local damage

give an example of a VEI 1-3 eruption

• Nyiragongo

• democratic republic of congo

• last eruption was in 2020

• VEI 2

• destroyed over 1000 homes and led to 32 deaths

describe VEI 4-5 eruptions

• moderate explosive eruptions capable of regional damage and disruption

give an example of a VEI 4-5

• Mount St Helen

• 1980

• VEI 5

• Washington

describe VEI 6+ eruptions

large to gigantic explosive eruptions capable of global impact through climate modification

give an example of a VEI 6+ eruption

• Mount Pinatubo

• Philippines

• VEI 6

• 1991

how are volcanoes predicted

• seismometers and seismographs- allow governments to issue warnings of imminent eruption

how successful is eruption prediction

• generally successful

• can be aided by evidence from previous eruptions

• lahar and pyroclastic deposits can aid prediction

where is the mid ocean ridge

between the african plate and the arabian plate

describe the great african rift valley

• 6000 to 7000 km geographical trench

• stretches from Southwest Asia to Mozambique

• formed by the splitting of tectonic plates

describe Mid ocean trenches

• at a boundary between two oceanic trenches

• regular breaks in the ridge are called transform faults

• faults occur at right angles to the ridge- widen and different rates causing shallow focus earthquakes

• deep rift goes along the middle of the ridges which separates two plates

• magma rises at the rift and creates a new crust

what is a shallow focus earthquake

occur at a depth of less than 70km

describe rift valleys

• boundary between two continental plates

• the lithosphere stretches causing fractures in the faults

• the land collapses into valleys which are separated by blocks of land called horsts