Hazards Flashcards
Define hazard
A natural hazard is a perceived natural/geophysical event that has the potential to threaten both life and property
What are tectonic hazards?
Large scale processes associated with the movement of tectonic plates
Volcanic: pyroclastic flows, ash fallout, tephra, lava flows
Seismic: Ground shaking, liquefaction, tsunami
Hydrological hazards?
glacial flooding, river flooding, storm surge and coastal flooding
Atmospheric hazards?
Drought, tropical storm, acid rain
Geomorphic hazards?
Landslides, mudflows
Biohazards?
Wild fires
How can impacts of hazards be categorised?
Social, political, environmental, economic, demographic, primary, secondary, short term, long term (temporal scale), local, national, regional, global (spatial scale).
Define disaster
The realisation of a hazard when it causes a significant impact on a vulnerable population. The hazard exceeds the capacity and resilience level of the population.
Define vulnerability?
The risk of exposure to hazards, combined with an inability to cope with them.
How does a hazard become a disaster?
Hazard event + vulnerable population
UN definition of a disaster?
Report of 10+ people killed
Report of 100+ people affected
Declaration of a state emergency by the relevant government
Request by national government for international assistance
Factors encouraging a hazard to develop into a disaster?
Magnitude Frequency Duration Areal extent Spatial concentration Speed of onset Regularity
How does frequency affect a disaster?
Usually an inverse relationship between frequency and magnitude
Areas experiencing lots of disasters often have lots of adaption and mitigation measures in place.
What is areal extent?
The size of the area covered by the hazard eg ash clouds can cover a large part of the atmosphere.
What human factors affect whether a hazard turns into a disaster or not?
Economic factors, social factors, political factors, geographical factors, technological factors (building design), and environmental factors.
Define risk
The probability of a hazard ocurring and creating a lossof lives and/or livelihoods.
Define resilience
The degree to which a population or environment can absorb a hazardous event and yet remain within the same state of organisation i.e. its ability to cope with stress and recover.
What is economic resilience?
Diversity of economic income/activity - not reliant on one sector
savings for recovery - on national scale and individual scale
Access to aid and trade
Insurance (individual scale) companies
Social resilience?
Community preparedness
Community relationships and networks
Why do people live in hazardous locations?
Rewards outweigh risks e.g. fertile soils have high agricultural potential.
Cultural connections to landscape place
Risks are effectively mitigated by hazard management.
Lower income communities may have no alternative.
Perception of hazard
Political factors eg refugees forces to settle
Lack of awareness
Define fatalism? hazard perception
View that people cannot shape the out come, nothing can be done
Define adjustment/adaption? hazard perception
People see that they can prepare for, and therefre survive the events by prediction, prevention and/or protection, depending on the economic and technological circumstances of the area in question.
Define fear? hazard perception
The perception of the hazard is such that people feel so vulnerable to an event that they’re no longer able to face living in the area and move away to regions to be unaffected by the hazard.
Reasons for differences in hazard perception?
Socio-economic status - have the money to prepare
Occupation/employment status-stable employment so may avoid risks of losing job if move away
Level of investment in risk awareness programmes - aware so know what to expect
Level of education - adjustment as know how to adapt
Religion/cultural - may not want to move away due to cultural connection, family
Family/Marital status
Values/expectations/personality
Define mitigation
The reduction in the amount and scale of threat and damage caused by a hazardous event
Define integrated risk management
the process of considering the social, economic and political factors involved in risk analysis, determining the ‘acceptibility’ of damage/disruptions; deciding on the action to be taken to minimise damage/disruption.
Define risk sharing
Pre-arranged measures that aim to reduce the loss of life and property damage through public education and awareness programmmes, evacuation procedures, the provision of emergency medical, food and shelter supplies, and the taking out of insurance.
What’re the stages of integrated risk management?
Establishing the context Risk identification Risk analysis Risk evaluation Risk treatment
What is the disaster response curve?
Shows how quality of life detereorates after a disaster, before improving again. Stage 1 is the disaster itself. Stage 2 is the use of vulnerability strategies. At stage 3, search and rescue continues and the quaity of life begins to improve again. STage 4 involves relief and rehab with the potential of outside help to modify the loss eg temporary housing. Stage 5 includes restoration of normality (reconstruction). After, quality of life can improve above that of pre-disaster, as buildings are reconstructed and mitigation strategies implemented.
Pre disaster - relief - rehabilitation - reconstruction
What is the hazard management cycle?
Pre-disaster (risk assessment, mitigation/prevention, preparedness
Response (warning/evacuation, saving people, immediate assistance, assessing damage)
Post-disaster (ongoing assistance, restoration of infrastructural services, reconstruction, economic and social recovery, ongoing development activities, risk assessment/mitigation/prevention.
Four stages: mitigation, preparedness, response and recovery.
What is fire?
The rapid combustion of oxygen with carbon, hydrogen and other organic material in a reaction producing flame, heat and light.
What are the stages of a wildfire?
Preignition
- pre-heating: fuel drives out due to nearby flames or hot weather
-pyrolysis: wood breaks down chemically, releasing gases, oils etc. Materials are now ready for ignition eg by lighting, electrical wires
Flaming combustion: burning gases = fast, hot fire. Wood cracks, releasing more gases, resins, oils, which are then ignited.
Glowing combustion: fire consumes wood itself = slower, cooler fire.
How does fire behaviour effect the nature of fires?
Crown fire
Surface fire
Ground fire
How does fuel characteristics affect the nature of fires?
Quantity of fuel Size and distribution of fuel elements Energy content of fuel Content of resins, oils, waxes Moisture content
How does climate affect the nature of fires?
Drought/dry weather allows pre-heating
Low humidity = dryer conditions
Semi arid climate = enough precip for vegetation to grow to provide fuel, yet with a dry season to promote ignition.
Foehn winds: cool air rises over relief and heats up as it sinks on the leeward side. Warm air drives fires.
Define convection column
The rising column of gases, smoke, fly ash, particulates, and other debris produced by a fire - can form pyrocumulus clouds.
What is a fire tornado?
Roaring spouts of flames shooting 100 foot into the sky. Forms when a fire heats the air above it, and pulls in cool air at the base, creating a self-sustaining vortex. The vortex also sucks up combustable gases.
What affect do wind speeds have on wildfires?
Light winds: vertical convection column, slow speed
Strong winds: fires move fast, spreads quickly, creates additional hazards. Convection column, firebrands (burning embers, spread randomly) and ‘firenados’.
Very strong winds: fire moves fast. Fire front advances very quickly but not convection column.
How does relief affect wildfires?
If the fire is spreading uphill, there is limited pre-warming of downhill vegetation and so the fire slows down.
If wind is driving the fire uphill, convectuve currents drive the fire uphill which pre-warms and dries out the vegetation.
What areas have the highest fire counts?
Eastern South America
Southern Africa
Northern Australia
Physical causes and exacerbating factors of wildfires?
- dry terrain
- extreme heat
- lightning
- hot volcanic lava
- earthquakes
- drought/little rain
- flammable resin to benefit plants
Human causes and exacerbating factors of wildfires?
Arson Camp fire carelessness Electricity lines/power lines Railways Mis-managed forests Slash and burn agriculture
Short term individual responses to wildfires?
Fill as many containers with water
Place lawn sprinklers in accessible places
Place a ladder against the wall of the house
Turn on as many lights in the house as possible to increase house visibility through smoke.
Short term professional responses to wildfires?
Emergency response eg firefighters, medical services, search and rescue
Creating fire lines
Planes and helicopters - contains water and chemical slurry to smother the flames and fertiliser to protect trees.
4 ways of managing wildfires?
Mitigation
Preparedness
Prevention
Adaption
Give examples of some wildfire responses and managemnet?
Suppress all fires Controlled burning Hazard-resistant design for buildings Notice boards to warn tourists Land-use planning Insurance Infrared remote sensing Weather monitors 30m setback from any forested areas.
Define insolation
Incoming solar radiation that varies significantly on earth.
Define differential heating
Different latitudes recieve different amounts of heat energy.
Define tropical storm
An intense, circular, low pressure weather system that develops over Tropical Oceans, is associated with high winds (120 km/hour +), and heavy rainfall and represents a severe hazard.
India = cyclone
North Atlantic = hurricane
South East Asia = typhoon
Factors affecting the development of a tropical storm?
Oceans and high temperature - form over oceans with a temperature of 26 degrees celsius and above.
Atmospheric instability - forms in instable regions where warm air is being forced to rise eg the ITCZ
Rotation of the earth - explains why tropical storms do not usually form in the region between 5 degrees north and 5 degrees south.
Uniform wind direction at all levels: vertical development would be ‘sheared off’ by multidirectional winds.
60m deep heat.
What causes a tropical storm to rotate?
The coriolis effect
What is the eye wall?
Dense wall or ring of thunderstorms and high winds surrounding the eye
What is the eye?
A column of dry, sinking air at the centre of a storm 30-60km.
What’re spiral rainbands?
Curved bands of clouds and storms that spiral around the centre of the storm. Can extend for hundreds of miles.
What’re towering colonimbus clouds?
Huge thunderclouds associated with heavy rain, lightning, hail and produced by condensation of warm, moist air.
What hazards are associated with tropical storms?
Strong winds
Storm surges
Coastal and river flooding
Landslides
Key facts about the character of Hurricane Maria?
2017 Category 4 155mph sustained wind speed 1.8-2.7m storm surge 96.5cm of rainfall in one storm
Where was Hurricane Maria?
Puerto Rico
Background of Puerto Rico (area hit by Hurricane Maria)
Had been facing a recession for over a decade before the hurricane hit.
Almost half of its residents are below the poverty line
Unemployment rate more than double the national level
When was the last category 4 hurricane to hit puerto rico?
85 years before
What are some excarerbating factors of hurricane maria?
Damage from category 5 hurricane Irma just two weeks before: crippling the electrical grid and leaving 3.4 million residents without electricity. Less than one percent of homeowners had flood insurance.
Social impacts of Hurricane Maria?
Poorest residents were disproportionately affected as they live in hard to reach areas near the mountains, so can expect to be the last group to regain access to water and electricity
Pshychological impacts of the storm
Took nearly 5 weeks for the first public schools to begin opening again after the storm
6 months after the storm many were still without power - Puerto Rico Electrical Power Authority filed for bankrupcy.
How many direct deaths were there from hurricane maria?
65
How many indirect deaths were there from Hurricane Maria?
2975
How many school students were affected by Irma and Maria?
350000
Economic impacts of Hurricane Maria?
£73.4 billion in damages
80% of the crop value wiped out
1/3 workers are employed in small to medium sized businesses and farms were especially hit - 90% drop in customers over the prior year.
How much money from damage did Maria cost to Puerto Rico?
$90 billion (third costliest storm in US history)
