Hazards Flashcards
What is a Hazard?
A potential threat to human life and property caused by an event.
Becomes a hazard when it poses a threat to people.
What is a Disaster?
The result of a hazard occurring with loss of life and damage to the built and natural environment.
What are the characteristics of hazards?
- Clear origins and effects
- Short warning times
- Involuntary exposure
- Most loss occurs immediately after the event
- Requires emergency response
What are the three types of Natural Hazards?
GEOPHYSICAL- Hazards caused by land processes i.e. earthquakes and volcanos
ATMOSPHERIC- Caused by atmospheric processes i.e. tropical storms and wildfires
HYDROLOGICAL- Caused by water bodies and movements like tsunamis and floods
What’s the difference between risk and vulnerability?
Risk- The exposure of people to a hazard presenting a possible threat to life, possessions, and the built environment.
Vulnerability- The potential for loss of life and possessions, varying between social groups, locations, and timescales.
Why do people live in hazard- prone areas?
- Low perceived risk
- Lack of alternatives
- Risk levels change over time
-Benefits outweigh costs - Family history
- Tourism income
- Scenic views
- Volcanic soil is fertile
What are the three hazard perception approaches?
Fatalism: Accepting hazards as natural events beyond control
Adaptation: Preparing effectively to survive events
Fear: Feeling too vulnerable to live in the area
What are the factors influencing hazard perception?
- Socio-economic status
- Level of education
- Occupational status
- Religion and cultural background
- Family and marital status
- Past experience
- Values and expectations
- Geographical stats
What are the three methods of hazard management?
Prediction: Warnings through monitoring systems
Prevention: Often unrealistic (e.g., stopping tropical storms)
Protection: Modifications to built environments (e.g., sea walls)
What is integrated risk management?
process considering all factors (social, economic and political) involved in risk management. This determines the acceptability of damage and disruption and deciding the actions to reduce and mitigate this.
What are the steps in integrated risk management?
- Identification
- Analysis of risks
- Establishing priorities
- Risk reduction
- Public awareness
- Monitoring and reviewing
Give examples of successful hazard management
Mt. Etna: Used dynamite to divert lava flows
Iceland (1978): Used dynamite to prevent lava cutting off the harbor
Give examples of unsuccessful hazard management
Japan (1995): Great Hanshin Earthquake destroyed 10,000+ buildings despite preparation
What are the steps in the hazard management cycle?
Preparedness: Education, risk assessment
Response: Immediate actions (rescue, warning, evacuation)
Recovery: Short- and long-term restoration
Mitigation: Future impact reduction via defenses & infrastructure
What does the park model show?
Illustrates hazard impact on quality of life over time
Influencing factors: Hazard type, intensity, infrastructure, economic status
Possible improvements post-event: Better infrastructure, awareness, investment, emergency aid
What are the key hazard characteristics?
Distribution: Spatial coverage (area or location affected)
Frequency: How often hazards occur
Magnitude: Size and impact of the hazard
What is the shape of the Earth called and why?
The Earth is a geoid, meaning it bulges at the equator and flattens at the poles due to centrifugal forces.
What are the four main layers of the Earth?
Crust, Mantle, Outer Core, Inner Core.
What is the difference between the inner and outer core?
The inner core is solid (iron/nickel) due to high pressure, while the outer core is semi-molten.
What are the two types of crust and their characteristics?
Continental crust: Thick (30-70 km), Old (1.5 billion years), Low Density, Made of SIAL (Granite).
Oceanic crust: Thin (6-10 km), Young (200 million years), High Density, Made of SIMA (Basalt).
What are the two sources of heat inside the Earth?
Primordial heat (leftover from Earth’s formation)
Radiogenic heat (from radioactive decay).
What is the lithosphere and how does it interact with the asthenosphere?
The lithosphere is broken into tectonic plates, which move on the semi-molten asthenosphere due to convection currents.
Who proposed the Continental Drift Theory, and what was the key evidence?
Alfred Wegener (1912) proposed that continents were once a single landmass (Pangaea). Evidence includes:
- Fit of the coastlines (e.g., South America & Africa)
- Fossil correlation (e.g., Mesosaurus found in Africa & South America)
- Geological correlation (similar rock formations across continents)
- Paleo-climate data (e.g., glacial deposits in warm regions)
How did sea-floor spreading support plate tectonic theory?
Discovery of the Mid-Atlantic Ridge and:
- Age of Rocks: Youngest in the center, older outward.
- Magnetic Reversals: Alternating bands of rock show changes in Earth’s polarity every 400,000 years.
What are convection currents, and how do they drive plate movement?
Hot magma rises, spreads, cools, and sinks, creating movement that drags tectonic plates.
What is ridge push (gravitational sliding)?
Magma rising at mid-ocean ridges pushes plates apart due to gravity
What is slab pull?
At destructive margins, the denser oceanic plate subducts, pulling the rest of the plate with it.
What happens at a constructive boundary?
Two plates move apart, creating new crust from rising magma.
What landforms are associated with constructive boundaries?
Oceanic Setting: Mid-ocean ridges (e.g., Mid-Atlantic Ridge).
Continental Setting: Rift valleys (e.g., East African Rift Valley).
What are the three types of destructive plate interactions?
Oceanic vs. Continental: Subduction forms deep-sea trenches (e.g., Mariana Trench) and volcanoes.
Oceanic vs. Oceanic: The denser plate subducts, forming island arcs (e.g., Japan).
Continental vs. Continental: Plates collide, creating fold mountains (e.g., Himalayas).
What is the Benioff Zone?
The area in a subduction zone where the oceanic plate melts, causing earthquakes and volcanic activity.
What happens at a conservative boundary?
Plates slide past each other, causing earthquakes but no volcanic activity (e.g., San Andreas Fault).
What are magma plumes and how do they relate to plate movement?
Rising columns of hot magma create volcanic hotspots (e.g., Hawaii). As plates move, old volcanoes become extinct, and new ones form.
Where are volcanoes most commonly found?
At plate boundaries, especially constructive and destructive margins. Also in high-activity areas like the Ring of Fire and at hotspots (e.g., Hawaii).
What scale is used to measure volcanic explosivity?
The Volcanic Explosivity Index (VEI), a logarithmic scale from VEI 2 onwards, considering tephra volume, eruption duration, and plume height.
How do scientists determine eruption frequency?
By studying historical records, deposited materials, and ice cores.
What are the three classifications of volcanoes?
Active (frequently erupting), Dormant (inactive but could erupt), Extinct (unlikely to erupt).
Talk about Icelandic eruption style
The least explosive where lava flows gently and slowly allowing it to cool and condense and form new land
effusive
Talk about the Hawaiian eruption style
Still slow moving lava but a bit more explosive than Icelandic. Usually occurs on hotspots with the lava cooling and condensing when it hits water. This usually makes a dome shaped volcano. effusive
Talk about the strombolian eruption style?
These are frequent, explosive volcanoes with lava bombs, tephra and steam explosions and occasional short lava flows. Here ash clouds are more noticeable than the other two
Talk about the vulcanian eruption style.
Less frequent but more violent with large amounts of gas, ash and tephra released. They are known as having a sustained ash cloud column, pyroclastic flows and volcanic bombs.
Talk about the Plinian eruption style
Extremely violent eruptions with big ash and gas clouds, pumice bombs, torrential rainstorms and devastating lahars.
What is tephra?
Solid materials ejected into the air during an eruption.
What are pyroclastic flows?
Fast-moving, 800°C, high-velocity flows of gas and tephra, moving up to 700 km/h.
What are the two types of lava flows?
Pahoehoe - Smooth and gloopy
Aa - Rough and jagged
Name four volcanic gases released during eruptions.
CO₂, Carbon monoxide, Chlorine, Sulphur dioxide.
How does acid rain form from volcanic eruptions?
Sulphur dioxide mixes with atmospheric moisture, causing acidic precipitation.
Give examples of social impacts of a volcanic eruption.
People killed, homes destroyed, Fires can start, mudflows, floods, trauma, homelessness
Give examples of environmental impacts of a volcanic eruption.
Ecosystems damaged through varous hazards, wildlife killed, Water acidified by acid rain, volcanic gases contribute to greenhouse gas effect.
Give examples of economic impacts of a volcanic eruption.
Businesses and indistires destroyed or disrupted, Jobs lost, profit from tourism industry after
Give examples of Short term responses of volcanoes
Financial aid food and water. temporary infrastructure early. alert alarm systems. Troops and Navy aid. exclusion zones. Evacuation
Give examples of long- term responses
Long term financial aid redevelopment permanent migration. mitigation infrastructure.
Why is it difficult to predict volcanic eruptions?
Volcanoes do not always show clear warning signs, and prediction is not 100% accurate
Name four ways scientists monitor volcanic activity.
Ground deformation (e.g., bulging of land).
Gas emissions (increase in sulphur dioxide).
Seismic activity (more earthquakes).
Changes in groundwater temperature.
Define an Earthquake.
Sudden and brief periods of intense ground shaking caused by movements within the Earths crust or aesthenosphere which occur during a release of stress along faults where friction between plates temporarily prevent the movements. When stress overcomes, energy releases seismic waves causing the ground to shake.
Name the makeup of earthquakes
Focus- this is the exact point where the preassure release occurs. This is also known as the hypocentre
Epicentre- Directly above the focus on the surface
Name the three categories of Earthquake depth
Shallow- 0-70km, most damaging, 76% of the worlds quakes
Intermediate-70-300km
Deep-** 300- 700km
Talk about the distribution of Earthquakes
The majority of earthqake zones are found along plate margaines with the ring of fire accounts for 90% of the worlds Earthquakes. All of Earth’s boundaries have earthquakes with only a few spots being throght the plate when old fault line reactivates. The most poweful earthquakes occur at destructive margains and least at constructive
What are the three ways of measuring Earthquakes?
Richter Scale
Moment Magnitude Scale (MMS)
Mercalli Scale
Talk about the Richter Scale
This measures the magnitude of Earthquakes. Its a logorithmic scale meaning an Earthquake at 7 has an amplitude of 10x greater than at 6. The energy released is proportional to the magnitude so that for each unit increase, energy is released about 30 times. However, this isnt as useful to measure more powerful earthquakes, MMS may be more useful.
Talk about the MMS
Moment Magnitude Scale (MMS)- measures the total energy released. many geologists were unhappy with the fundementals of the richter scale and now this is more unusual. same scale as richter at 1- 10
Talk about the Mercalli Scale
This measures the intensitu of an event by considering its impact on the wider world. It is a 12 point scale where 1 is approximate to 2 on the richter scale.
However, this is subjective.
What are the wave categories and the types of waves
BODY WAVES- Primary waves (P waves), Secondary waves (S waves)
SURFACE WAVES- Love waves, Raleigh waves
What’s the difference between S waves and P waves?
P- These are the fastest seismic wave reaching between 6-8 km per second. They are compressional waves that travel through the mantle and core. This is the least destructive wave.
S- These are slower at around 3-4km per second, They move side to side or up and down making them more damaging. They only go through the mantle not the core.
What’s the difference between love and Raleigh waves
Love- These are the slowest waves at between 2- 4km per second. They move up and down making them the most damaging waves
Raleigh- These originate from the centre and make a complicated eliptical motion making them also damaging
Talk about the frequency of Earthquakes
Earthquakes are frequent around the world and occur every day at boundaries. Hundreds of smaller magnitude earthquakes that cannot be felt by humans occur everyday while larger earthquakes are less frequent.
Earthquakes follow no pattern and are random so there is irregularity between events
What are the Environmental effects of Earthquakes?
Primary:
- Soil Liquification - Fault Lines, Destroy the environment.
Secondary:
- Radioactive materials and other dangerous substances leaked from power plants. - saltwater tsunamis flood freshwater ecosystems. - soil Salinisation
What are the economic effects of Earthquakes?
Primary-
- businesses destroyed
Secondary:
- Economic decline as businesses are destroyed.
- high cost of rebuilding and insurance payout.
- sources of income lost
What are the social effects of Earthquakes
- Buildings collapse killing people and trapping them
- Gas pipes rapture, starting fires which can kill - Water supplies are contaminated as pipes burst spreading disease - Tsunamis damage
What are the political effects of Earthquakes?
- Government buildings destroyed
- Political undrest from food and water shortages - Borrowinf money needed from aid nationally and internationally. - Can be initial chaos i.e. looting
What is Soil Liquification
When the water saturated ground shakes due to earthquakes, water is forced upwards making the topsoil behave more fluid. This can lead to ground deformation and infrastructural damage.
What is a tsunami?
When an oceanic crust is jolted during an earthquake, all of the water above is displaced. This water trabels fast but with a low amplitude. As it gets closer to the coast, the sea level decreases so there is friction between the bed and waves causing the waves to gain height creating a tsunami.
What are the characteristics of Tsunamis?
- Long Wavelengths- over 100km
- Low Wave Height- can be under 1m or up to 25m
- Fast Speeds- of around 700km/h
- Long Wave Periods- 10- 60 mins between waves.
What are the effects of tsunamis dependent on?
- wave height
- distance from the epicentre
- amount of warning
- coastal geograhy
- land- use
- population density
- management
Talk about prediction of Earthquakes
It is extremely difficult to predict Earthquakes, however, we can indentify regions at risk. We do this by plate tectonics and geology, however, these are all implications- doesnt happen in all earthquakes
What are some monitoring methods we could do to monitor earthquakes?
- Radon gas emissions
- groundwater levels
- animal behaviours
- local magnetic fields along fault lines.
Talk about seismic gaps
The area of Loma prieta had not had any seismic activity for 20 years (since 1906) and was designated a seismic gap. In 1989, a 6.9mms earthquake hit the area killing 63 and causing $1 billion in damages. However, scientists werent suprised as between 1969-88 there was a lack of activity- gap- and therefore was identified as an area where an earthquake could occur.
What are some outlandish prevention ideas for Earthquakes
- Sticking the plates together- expensive, builds up more preassure, steel would melt
- Lubrication using water and oil- evaporation
- Underground nuclear explosions
Talk about the Federal Emergency Management Agency
FEMA- This is an organisation which promotes the understanding of earthquakes and its effects and work to better identify risks. They do this by improving the design of buildings and construction techniques. They also encourage the use of planning practices and policies.
Talk about Insurance as a protection method for Earthquakes
In richer areas, people take out insurance to cover losses and work towards long- term economic stability. However, this can be expensive.
Talk about Hazard Resistant Structures in protecting against earthquakes
- large concrete weight on the top of buildings which moves in the opposite direction to the force to counteract stress.
- Shock absorbers in foundations allow the movement of buildings
- Adding cross bracing holds together buildings
- Counterbalancing- GPS activated metronome to counteract movement
Talk about Education as protection for earthquakes
This is given out by authorities. Info includes how to secure homes, appliances and furniture, making earthquake kits and earthquake drills.
Disaster prevention day in Japan marks the anniversary of the Tokyo Earthquake, 1st Sept
Also, American Red Cross issues Kits with water, food, bedding, tools, first aid kit ect.
Talk about retrofitting as a protection against earthquakes
Added into old buildings to make more earthquake proof. Methods involve, steel cross bracing, sloshtanks, outersteel structures and external post tensioning
A 6.9mms in Armenia resulted in 25,000 deaths when a 6.8mms in California resulted in 63.
Talk about fire prevention to prevent against earthquakes
Smart meters can cut of gas if an earthquake hits a significant magnitude.
Tokyo gas company have a network which transmits seismic info to tell them to switch it off reducing the amount of fires
Talk about AID as a protection against Earthquakes
This includes short- term medical services from other countries and organisations like the UN and WHO who set out services, tents and search and rescue teams. Long- term aid can also be set out including money and reconstruction of the built environment and the economy.
Talk about Emergency Services as protection against earthquakes
Careful organisation and planning is needed with heavy lifting and first aid training. California establish computer programs using GIS to target where to send emergency services.
Talk about tsunami protection
Can’t be entirely predicted even if an earthquake is known. Automated systems installed using bottom preassure buoys to warn. Prevention walls of up to 12km are largely seen as ill-effective.
The pacific warning system is based in hawaii telling countries around the pacific edge for any warnings catalysed by the boxing day tsunami
Talk about land use planning as protection against earthquakes
The most hazardous areas can be identified and regulated in ter,s of land use with schools and hospitals put in low risk areas. It also includes open spaces to make a safe areas from fires and aftershock damages
What are tropical storms and the importance?
Intense low preassure systems originating in the tropics which rotate rapidly resulting in powerful winds. They are entirely naturally occurring although anthropogenic climate change increases the intensity and frequency of them.
Despite them causing a dramatic loss of life and damage, the planet relies on them. Without them, there wouldn’t be redistribution of heat as they transfer warm conditions from the tropics toward the poles.
What are the three names of tropical storms?
- Typhoons- In the South China Sea and West Pacific Ocean
- Hurricanes- in the gulf of Mexico, Caribbean Sea and west coast of Mexico
- Cyclones- in the Bay of Bengal, Indian Ocean and northern Australia
What are the characteristics of Tropical storms?
- Heavy bands of rainfall producing 200-300mm of rain.
- High windspeeds of over 74mph
- High waves and storm surges
- Lasts for 7 to 14 days
- Can be 200 - 700km in Diameter
- Eye is roughly 10-15 km in diameter with sinking cold air and no wind
- They develop in tropical regions between 5° and 20° north and south of the equator
Talk about the distribution of tropical storms
Tropical storms are found along the tropics never crossing the equator. The largest amounts occur around the Philippines and Western America. More occur in the northern hemisphere, the tracks always go away from the equator. They move anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere
What are the factors affecting the formation of tropical storms?
- Ocean temperatures of 26-27 degrees centigrade
- Ocean depth of 70m
- calm ocean
- low wind sheer
- atmospheric instability
- Rapid outflow of air
- low level convergence
- Develop between 5° and 20° north and south of the equator
Why are the factors needed for tropical storm formation needed?
Temperature- needed for power via evaporation and condensation
Low wind sheer- if the wind shear is too high, it can disrupt the organization of the storm and prevent it from strengthening
Atmospheric instability- In tropical regions, warm, moist air near the surface rises creating instability and leading to the formation of clouds and precipitation
Rapid outflow of air- in the upper atmosphere circulation- pushes away warm risen air from the centre.
Low level convergence- wind comes together near the centre of the low preassure zone
Equator north and south- maximum rotation of air
Talk about the importance of the coreolis effect in the formation of tropical storms
This is the bending of air masses due to the equator moving faster than the poles. This causes airmasses to rise and spin as air bends East and West creating circular movements of air.
What are the stages in tropical storm formation
- Warm air rises forming an area of low preassure
- Air from high preassure rushes to take place of the rising air, generating strong winds which rises forming a continuous flow of rising air
- As the air rises it cools and condenses forming cumulonimbus clouds forming the eye wall of the storm producing heavy rainfall.
- Condesnation releases energy helping power the storm
- The coreolis effect causing the rising air to spiral around the centre, cold air sinks in the centre forming the eye.
Talk about measuring tropical storms
We measure using the Saffir- Simpson Scale which is based on wind speeds, central preassure, storm surge height and the amount of potential damage. It rates from 1 to 5.
Tropical storms are cosidered major when they reach category 3 with wind speeds between 111-129 miles per hour. A category 5 storm can deliver speeds of over 157 miles an hour
What are the hazards associated with tropical storms?
- strong winds
- storm surges
- intense rainfall
- coastal and river flooding
- landslides
Talk about strong wind as hazards of a tropical storm
Strong Winds- average at over 75mph and gusts can reach over 250km/h at the eye wall. This destroys by tearing roofs, breaking windows, communication networks, fires and uprooting trees causing disruption
Talk about storm surges as a hazard of tropical storms
Storm Surges- surge of high waters around 3m caused when large volumes of water are forced inland by the low preassure and strong winds. They cause extensive flooding, erode beaches, damage sea defences and contaminate farmland and freshwater.
Talk about intense rainfall as a hazards of tropical storms
Intense Rainfall- leading to flash flooding, damaging properties and injuring people from fast flowing water
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Talk about coastal and river flooding as a hazard associated with tropical storms
Warm, humid air can generate torrential rainfall often in excess of 200mm in just a few hours. This can trigger flash flooding which can overwhelm the drainage system, catalysed by the impermeable surfaces of urban areas.
Talk about landslides as a hazard of tropical storms
90% of landslides each year are caused by heavy rainfall which increases pore water preassure, weakening cohesion triggering slope faliure
Talk about the frequency and regularity of tropical storms
Tropical storms are relatively frequent in many parts of the world, but the frequency can vary significantly from year to year. On average, there are about 80 tropical storms each year. The highest number of tropical storms form over the Pacific Ocean (on average over 50 per year). In the Atlantic Basin (which includes the Caribbean Sea and the Gulf of Mexico) an average of 12 tropical storms form each season, with around 6 of these becoming hurricanes. Tropical storms tend to occur during tropical storm season
Talk about the regularity of tropical storms in the Northern and Southern Hemisphere
- In the Northern Hemisphere, this runs from June to November, with the peak months falling in August, September and October
- In the Southern Hemisphere, the season runs from November to April, with peak months falling in January, February and March
Talk about the prediction of tropical storms
To some extent, we can predict tropical storms, we know they:
- Occur close to the equator
- During late summer - autumn and peaks august - october
We know that atmospheric conditions, ocean temperatures and localised weather events like El Nino and La Nina are all factors which can help predict storm seasons and we can predict the path of where they make landfall.
However, as storms follow erratic paths and are hard to plot, accurate estimation is limited to 12-18 hours beforehand which may not be suffiecient enough.
Talk about the primary effects of tropical storms
Death and Injury, Displacement of People, Damage to properties and infrastructure causing disruption to peoples life
Destruction of property and infrastructure leading to costs for repair and reconstruction, Disruption of trade and economic activity, loss of income and employment, Costs of immediate responses
Poor water quality due to pollution, loss of biodiversity as freshwater habitats flooded with salt water, destruction of habitats and ecosystems
Preassure on governments to co-ordinate emergency response, social unrest and political instability
Talk about the secondary effects of tropical storms
Mental Health Issues, Homelessness, Disruption to services like healthcare and education, loss of cultural heritage sites
Slower economic growth and development, increased economic inequality as impacts are more severe for vulnerable, increased costs of insurance and hazard management strategies
Soil erosion and land degration leading to decreased soil fertility, loss of habitat and biodiversity can affect other species like migration of birds, loss of coral reefs, sand dunes and mangrove forests
Conflicts over government responses and food shortages, changes in government policy and regulations
Talk about the short- term responses of earthquakes
Evacuation of people before the tropical storm arrives, rescue people before the storm cuts people off from flooding and treat injured people, recover dead bodies prevent diesease, set up temporary shelters and supplies of power, food and water, overseas aid
Talk about the long term responses to tropical storms
Improving long-term forecasting techniques to help future, provide aid, grants or subsidies to residents to repair and strengthen their properties, repair and improve flood defences, rehouse, improve infrastructure, improve building regulations, encourage economic recovery
Talk about the preparedness of tropical storms
This involves making people more aware of hazards and taking actions to minimize. We do this mainly by education, most people in areas of risk are aware if the potential dangers through education and public awareness. This involves methods like planning evacuation routes and preparing a go bag- first aid kit, spare clothes, water etc.
- satalite planning can be used to track and identify tropical storms and helps issue warning
Talk about prevention of tropical storms
Some governmenrs investigated the potential of cloud seeding which is when crystals are dropped into clouds catalysing precipitation so the storm looses energy reducing it’s impact on land.
However, people claim that it has adverse global effecrs and can alter the global energy system. It also has ethical considerations: if a cat5 is on track to hit a HIC, but is reduced and hits a LIC at cat3, could have worse effecrs than before and who decides this?
What are some mitigation strategies of tropical storms?
-Structural responses
- disaster aid
- insurance
- retrofitting
- land-use
Talk about structural responses of tropical storms
- Protction from storm surges via soft (planting trees and build up beaches) and hard (sea walls) engineering
- Galverston Texas- Sea walls after sugre which killed 6,000
- Coral Reefs buffer storm surges
Talk about disaster aid in tropical storm mitigation
Immediate relief- search and rescue, food, medicine
Long-term relief- reconstruction efforts, loans, direct support
Government declares emergencies to trigger support financially and logistically- can come from NGO’s, other countries or global organisations
Talk about insurance and mitigation of tropical storms
his is widely used to mitigate tropical storm damage especially in HIC’s, in the USA, residants in hurricane prone areas are encouraged to insure
Talk about land-use planning as a mitigation of tropical storms
Identify areas at risk and dont build anything or less uselful buildungs there.
