HAZARDS

Hazard

• potential threat to human life and property caused by an event

• Only becomes a hazard when it is a threat to people

Geophysical hazard

• caused by land processes

• Normally tectonic

Atmospheric hazard

• caused by atmospheric processes and the conditions created by

• Eg weather systems causing wildfires

Hydrological hazard

• caused by water bodies and movement eg floods

Hazard perception

• people have different viewpoints of how dangerous hazards and what risks they pose

• Dependent of lifestyle factors including economic and cultural elements Including:

  • Wealth

  • Experience

  • Education

  • Religion and beliefs

  • Mobility

Fatalism

• viewpoint that hazards are uncontrollable and any losses should be accepted as there is nothing that can be done to stop them

Prediction

• using scientific research and past events in order to know when a hazard will take place So that warnings may be delivered and impacts of the hazard can be reduced

Adaptation

Attempting to live with hazards by adjusting lifestyle choices so that vulnerability to the hazard is lessened

Mitigation

Strategies carried out to lessen the severity of a hazard

Management

Coordinated strategies to reduce a hazards effects

Includes prediction, adaptation, and mitigation

Risk sharing

• form of community preparedness where they invest collectively to mitigate the impacts of future hazards

Incidence and human response

• frequency of a hazard

• Low incidence hazards are harder to predict and have less management strategies put in place

• Low incidence usually more intense than high incidence hazards

Distribution and human response

• where hazards occur geographically

• Areas of high hazard distribution are likely to have a lot of management strategies

• Those living there will be adapted to the hazardous landscape

Magnitude and human response

• High magnitude/intensity hazards will have worse effects meaning they require more management

Level of development and human response

• economic development will effect how a place can respond to a hazard

• An area with lower development is less likely to have effective mitigation strategies therefore the effects of a hazard will be more catastrophic

The park model

• graphical representation of human responses to hazards

• Steepness shows how quickly an area deteriorates and recovers

• Depth shows the scale of the disaster (lower curve=lower quality of life)

• Works as a control line to compare hazards

Stage 1 of the park model - relief

• hours-days

• Immediate local response: medical aid, search and rescue

• Immediate appeal for foreign aid

Stage 2 of the park model - rehabilitation

• days - weeks

• Services begin to be restored

• Temporary shelters and hospitals set up

• Food and water distributed

• Coordinated foreign aid eg peacekeeping forces

Stage 3 of the park model

• weeks - years

• Restoring the area to same or better quality of lie

• Area back to normal - ecosystem restored, crops regrown

• Infrastructure rebuilt

• Mitigation efforts for future event

Hazard management cycle

• outlines the stages of responding to events

• Preparedness - (EVENT) - response - recovery - mitigation

Evaluating the ffectiveness of models

• can it be applied to every hazard?

• Does it take into account aspects of hazards eg levels of development?

• Is there a timeframe?

• How does timeframe change?

• Does it present hazards currently? Effect fo climate change?

Inner/outer core

• inner: very hot due to pressure and radioactive decay. This heat is responsible for earths internal energy

• Outer: semi molten

Mantle

• mainly solid rocks

• Very top later of the mantle is semi-molten magma, known as the asthenosphere

• The lithosphere rests on top

Astenosphere

• semi-molten layer constantly moves due to flows of heat called convection currents

• Movements are powered by the heat from core

Lithosphere

• broken up into plates

• Majority of the lithosphere is within the mantle

• Top of the lithosphere is the crust

Crust

• thin top of the lithosphere

• Oceanic crust is dense and destroyed by plate movement, continental crust is less dense and not destroyed

Hotspots

• areas of volcanic activity that are not related to plate boundaries

• Hot magma plumes from the mantle rise and burn through weaker parts of the crust

• This can create volcanoes and islands

• The plume stays in the same place but the plate continues to move, which sometimes causes a chain of islands eg Hawaii

Volcanic hazards

• lava flows: speed depends on viscosity

• Lahars (mudflows): usually caused by melting ice at high latitudes

• Tephra: any type of rock that is ejected by a volcano

• Toxic gases: released during some eruptions (even CO2can be toxic as it can replace oxygen as it is heavier)

• Acid rain: caused when gases such as sulfur dioxide are released into the atmosphere

• Pyroclastic flows/Nuees Ardentes: clouds of burning hot ash and gas that collapses down a volcano at high speeds. 60-430mph

Spacial distribution of volcanoes

• along constructive or destructive boundaries or on hotspots

• Ring of fire is an area of high volcanic and earthquake activity located in the pacific

• Majority of volcanoes occur here

Primary effects of volcanoes

• ecosystems damaged

• Wildlife killed

• Businesses and industry destroyed/disrupted

• People killed

• Homes destroyed

Secondary impacts of volcanic hazards

• water acidified by acid rain

• Volcanic gases contribute to greenhouse effect

• Jobs lost

• Potential profit from tourism industry

• Fred may start

• Mudflows or foods

• Homelessness

• Conflicts concerning government response, food shortages, or insurance

Prevention of volcanic hazards

• cannot be prevented

• Only risk to people can be prevented by not allowing people near active volcanoes

Preparedness of volcanic hazards

• monitoring increases notice of volcanic eruptions, allowing for warnings

• Education of volcanoes in areas of risk

• Evacuation procedures planned

• Training response teams

Mitigation of volcanic hazards

• direct intervention eg concrete blocks to steer lava from areas of risk

• Evacuation zones

• Mitigating effects on health by having emergency aid and rescue

Adaptation to volcanic hazards

• moving away from high risk areas

• Capitalising on opportunities eg encouraging tourism

Seismic hazards

• at all boundaries, plates can become stuck due to friction between plates

• When plates are stuck, convection currents in the asthenosphere continue to push, building pressure

• Eventually the plates give way and release pressure in a sudden movement, causing a jolting motion in the plates

• This is responsible for seismic movement spreading through the ground in the form of seismic waves

• The focus is the point underground where the earthquake originates from

• Epicentre is the point directly above the focus on ground

Spacial distribution of earthquakes

• occur along all boundaries

• Ring of fire accounts for 90% of the worlds earthquakes

Hazards caused by seismic events

• shockwaves: potential enegry transferred into kinetic energy and is released and vibrates throughout the ground. Strongest closest to the focus

• Tsunamis

• Liquefaction: when soil is saturated, the vibrations of an earthquake cause it to act like a liquid. Soil becomes weaker and more likely to subside when it has large weight on it

• Landslides and avalanches: movement in soil or snow will cause it to become unstable

Primary impacts of seismic hazards

• can cause fault lines which damage the environment

• Liquefaction

• Businesses destroyed

• Buildings collapsing which threatens life

Secondary impacts of seismic hazards

• radioactive material leaked from power plants

• Saltwater from tsunamis flooding freshwater ecosystems

• Soil salinisation

• Economic decline

• High cost of rebuilding and insurance payout

• Gas pipe ruptures may cause fires

• Water supplies contaminated spreading disease

• Tsunamis causing flooding

• Political unrest

• Borrowing money for international aid

Prevention of seismic hazards

• majority cannot be prevented

• Liquefaction can be prevented though soil stabilisation

• Avalanches can be prevented through controlled explosions

Preparedness of seismic hazards

• extensive awareness strategies eg in Japan

• Tsunami warnings following earthquake event

• Evacuation plans and training

Mitigation of seismic events

• search and rescue, immediate emergency aid, and evacuation

• Demolishing older unsafe buildings

• Tsunamis wave breaks and sea walls to prevent flooding

Adaptation to seismic hazards

• moving away from areas of risk

• Insuring homes and businesses

• Building earthquake proof buildings

Tropical storm

• low pressure spinning storm with high winds and torrential rain

Conditions needed for a tropical storm

• ocean temperatures of 27 degrees and 50m deep

• Area of unstable air pressure (eg where high and low pressure areas converge)

• Wind needed for swirling motion

• Around the equator not on due to coriolis effect

Formation of tropical storms

1. Over land: rapidly rising warm air forming thunderstorms. No shear wind to destroy the storm

2. Easterly winds move the storm. Sea surface temperature over 26 and 50m deep. Rising warm air fuels the storm

3. Storm moves away from the equator due to the coriolis effect and begins to spin anti clockwise. Rising warm air continues to enlarge the storm

4. Increased speed and energy makes the thunderstorm a tropical storm. Bands of cloud with rising warm air through the clouds and cooler air sinking between the bands. Storm rotates around the eye

5. Once the storm reaches land, the warm rising air is stoped, removing the fuel of the storm. The storm dissipates.

Spacial distribution of tropical storms

• between 5 and 1 degrees latitude

• Likely to form in the ITCZ where the two limbs of the hadley cell converge to form low pressure

• Cyclones: Indian Ocean

• Hurricanes: Atlantic Ocean

• Typhoon: Pacific Ocean (most common)

Hazards caused by tropical storms

• high winds over 300km/h

• Flooding from storm surges and heavy rain

• Landslides due to oil becoming more saturated

Primary impacts of storm hazards

• beaches eroded and sand displaced

• Coastal habitats eg coral reefs destroyed

• Agricultural land damaged

• Drowning

• Debris carried by high winds

• Building destroyed

Secondary impacts of storm hazards

• river flooding/salt water contamination

• Water sources changing course from blockages

• Rebuilding costs

• Economic decline

• Homelessness

• Polluted water supplies

• Food shortages

• Pressure for government to do more about global warming

Prevention of storm hazards

• cannot be prevented

• Strategies to mitigate climate change could prevent higher category storms

Preparedness of storm hazards

• awareness though education

• Evacuation plans and training

• Satellite image tracking

• Storm warning systems and television broadcasting

Mitigation of storm hazards

• search and rescue, immediate emergency aid, evacuation

• Strengthening buildings and homes

• Clearing loose debris before storm

Adaptation to storm hazards

• move away from high risk areas

• Design buldings to withstand high winds and flood damage

• Flood defences eg houses on stilts and sea walls

Wildfires

• large, uncontrolled fire that spreads quickly through vegetation

Conditions favouring wildfires

• densely packed vegetation allows fires to spread quickly and easily

• Vegetation with flammable oils eg eucalyptus

• Dry vegetation

• Climates that have enough rainfall for sufficient plant growth but considerable dry spells and droughts eg California

• Wind causes fire to spread quicker

Impact of temperature rise on incidence of wildfires

• increases incidence and length of wildfire seasons

• “Forest fires in the US occur 5x more since the 70s and 80s, burning 6x area of land, an lasting 5x longer”

Fire behaviour

• spread quickly on hills are the heat rises

• May jump across rivers and into areas due o lit debris which causes it to spread

Crown/surface/ground fires

• crown: burn the entire tree from bottom to top. Most dangerous and destructive

• Surface fires: only burn leaf litter making them easy to extinguish

• Ground fires: burn dry peat or vegetation beneath the surface, and move slowly through the dried underground. Difficult to put out and can continue to burn throughout the year if weather conditions allow it

Causes of wildfires

• can be natural or human

• Normally caused by human activity (accidentally or by arson)

• Natural causes include lightning and volcanoes

• Human causes can be lit cigarettes, bbqs, agriculture and more

Primary impacts of wildfires

• air pollution from ash

• Water pollution

• Habitats destroyed

• Toxic gases

• Agricultural land destroyed

• Cost of firefighting

• Deaths

• Homes destroyed

Secondary impacts of wildfires

• Migration patterns of animals effected

• Increased CO2 release contributes to greenhouse effect

• High cost of rebuilding

• Discourages tourism

• Cancelled air travel

• Homeslessness

• Food shortages

• Health problems eg smoke inhalation causing asthma

• Government pressure to tackle climate change

Prevention and preparedness of wildfire hazards

• wildfire will not be eradicated entirely due to current climate

• Public awareness can prevent ignition of wildfires and prepare people

• Eg SMOKEY BEAR US mascot who provides information on preventing wildfires

• Evacuation plans, emergency services training, personal emergency plans

• Warning systems eg Rd flag warnings

• Evacuation zones setup

Mitigation of wildfire hazards

• mainly concerned with protecting those directly at risk and extinguishing the fire

• Firefighters dispatched on ground

• Water and flame retardants sprayed onto large areas using aircrafts

• Long term mitigation strategies work to reduce impacts before they occur, eg controlled burning which remove flammable materials so less fuel is available

• Fire breaks created to limit spread

• People living at risk of wildfires can ensure their homes do not contribute to wildfire spread by following campaigns such as Smokey bear

• Homes can be built using materials that do not release harmful substances when burnt

Adaptation of wildfire hazards

• insurance and clean up of homes

• Staying educated

• Globally adaptations to lifestyle to stop contributions to atmospheric CO2 levels