Hazards Flashcards
Hazard
An extreme event that threatens people, their property and settlements
When does a hazard become a disaster?
When it causes widespread destruction to property and lives
Risk
The probability of an event happening and the scale of its possible damage
Adjustment or mitigation
The ability of a population to take preventative or precautionary measures
Predictability
How easy hazards are to predict
A factor affecting risk
Frequency and severity of events
Hazard categories
Geological, Climatic, Biological, Technical
Outer core (Thickness, state, temperature)
2200km, liquid, 3000
Mantle (Thickness, state, temperature)
2900km, Solid buts flows (theological consistency), 375
Inner core (Thickness, state, temperature)
1270km, Solid (iron and nickel), 3000
Crust (Thickness, state, temperature)
0-70km, Solid (Granite and Basalt), 10
Oceanic crust (age, density, thickness, can/can’t subduct)
Newer (<200 million years old), Denser, 5km, can subduct
Continental crust (age, density, thickness, can/can’t subduct)
Older (1500 million years old), Less dense, 30km, can’t subduct
Lithosphere
Top 100km of the Earth (curst and mantle) that makes up the tectonic plates
Asthenosphere
The rest of the upper part of the mantle that acts as a lubricant for the tectonic plates to move on
How do tectonic plates move?
Slab pull, ridge push and convection currents
Worldwide distribution of earthquakes and volcanoes
- Uneven
- Mostly correlated with plate boundaries
- Some earthquakes can be away from boundaries due to human activity
- 75% of volcanoes in the pacific ring of fire
- Hotspot volcanoes formed away from boundaries where isolated plumes of magma rise up through the crust e.g. Hawaii
Divergent aka Constructive
2 oceanic plates moving apart creating effusive volcanoes and small earthquakes
Convergent aka Destructive
Oceanic plate subducts under continental plate creating powerful earthquakes and explosive volcanoes
Collision
2 continental plates collide creating powerful earthquakes and fold mountains
Transformative aka Conservative
2 continental plates slide past each other creating powerful earthquakes
Shield volcanoes
Short, gently sloping volcanoes composed of basaltic lava due to its low viscosity has effusive eruptions
Stratovolcanoes
Tall, steep sided volcanoes composed of alternating layers of lava and pyroclastic flow deposits due to stick, highly viscous, rhyolitic lava, have explosive eruptions
The scale by which we measure volcanic eruptions
Volcanic Explosivity Index
Primary hazards
Immediate effects resulting from the event
Secondary hazards
Things that happen as a result of primary hazards
Date of Fuego eruption
3rd June 2018
Height of Mt. Fuego
3763m
Plate boundary of Fuego
Cocos and Caribbean destructive
Distance from Guatemala City
48km
Speed of Fuego’s pyroclastic flow
> 100kmph
Physical effects of Fuego
Airport closed, 8500Ha of crop damaged and traffic chaos
Human effects of Fuego
- 110 killed
- 200 missing
- 1200 evacuated
- 3000 in temporary housing
- 1.7 million effected
Fuego aftermath
CONRED (National disaster management agency) accused of mismanaging disaster warnings
Fuego prologue
Scientists warned of eruption 8 hours before but it took 3 hours for evacuation orders to be issued
Kilauea eruption date
4th May 2018
Kilauea eruption ash cloud height
9km
Kilauea location
Hawaiian hotspot
Features of Kilauea
No pyroclastic flow
Physical effects of Kilauea
Communities of Vacationland and Kapoho destroyed, geothermal power plant closed, 32 square km covered in lava
Human effects of Kilauea
0 killed, 0 missing, 10000 evacuated and housed
Kilauea aftermath
Evacuation well managed
Kilauea prologue
Eruption predicted but scale misjudged
What are earthquakes caused by?
- Plates get stuck together due to friction and protrusions on the opposite plate
- Pressure builds up
- Pressure gets too great and the plates slip, the slipping causes energy to be released in the form of seismic waves
P waves
Primary waves pull the ground side to side
S waves
Secondary waves pull the ground up and down
Precursor events
Small tremors, increase in radon emissions, previous earthquakes
Factors impacting number of deaths
- Age of building
- Earthquake proofing
- Infrastructure damage
- Potential for soil liquefaction
- Population density
- Poverty
- Poor governance
- Depth of focus
- Magnitude (Richter scale)
- Number of aftershocks
- Level of development
- Time of day
- Distance from epicentre
- Proximity to secondary hazards e.g. tsunamis or landslides
Date of the Turkey-Syria earthquake
6th Feb 2023
Magnitude of the Turkey-Syria earthquake
7.8
Secondary earthquakes of the Turkey-Syria earthquakes
7.5 magnitude earthquake 10 hours later 128km North
Depth of the Turkey-Syria earthquake’s focus
18km
Area affect by the Turkey-Syria earthquake
350,000km squared
Human effects of the Turkey-Syria earthquake
- > 56000 killed
- 100000 injured
- Around 2.7 million homeless in Turkey
- Around 5.3 million homeless in Syria
Physical effects of the Turkey-Syria earthquake
- > 4 million buildings damaged
- Hospitals and runways destroyed
- > 453 Syrian schools destroyed
- Afrin dam damaged and burst (flooding and displacing 500 families)
- > $100 billion damage in Turkey
- > $5.1 billion damage in Syria
Aid given to Turkey-Syria earthquale
$3 million to Turkey, $3.5 million to Syria
Aftermath of Turkey-Syria earthquake
210 million tonnes of rubble removed in Turkey, construction of 300000 new houses
Time and date of Christchurch earthquake
12.51pm 22nd Feb 2011
Magnitude of Christchurch earthquake
6.3
Depth of Christchurch earthquake’s focus
4.99km
Human effects of Christchurch earthquake
185 killed, 3129 injured, 6800 minor injuries, 2200 in temporary housing, 1/5 population migrated out of Christchurch
Physical effects of Christchurch earthquake
100000 properties damaged, 10000 properties destroyed, $28 billion damage
Aid given to Christchurch earthquake
$7 million
Where are tropical cyclones located?
Tropical oceans 5-30 degrees N/S of the equator
What are the regional names of cyclones?
Hurricanes in the Atlantic and eastern Pacific, Cyclones in the Indian Ocean, Typhoons in the western Pacific
What are the requirements for a cyclone?
- Sea surface temperatures of >27 degrees
- Converging winds
- Low wind shear
- Coriolis force
Tropical storm wind speeds
> 34 mph
Cyclone wind speeds (Saffir-Simpson Scale)
Category 1 74-95 mph, category 5 >156 mph
Cyclone Idai date
14-15th March 2019
Cyclone Idai wind speeds
> 150 mph
Features of Cyclone Idai
2.5m high storm surge, flooding
Human effects of Cyclone Idai
- 2.6 million effected
- > 800 killed
- Many living in temporary camps without secure food, water and sanitation
- Increase in cases of diarrhoea, cholera and malaria
Physical effects of Cyclone Idai
Buildings, infrastructure and agricultural land destroyed
Aid given to Cyclone Idai
£620 million
Location of Cyclone Idai
Mozambique
Date of Hurricane Dorian
1-4th Sept 2019
Winds speeds of Hurricane Dorian
> 185 mph
Height of Hurricane Dorian’s storm surge
3.7-5.5m
Human effects of Hurricane Dorian
Effected >6000, >70 killed, limited water, electricity and sanitation, evacuees sent to other islands
Physical effects of Hurricane Dorian
Flooding covered 60% of Grand Bahama, contamination and shut down of largest hospital on Grand Bahama
Aid given to Hurricane Dorian
$1 million
Factors affecting vulnerability to hazards
- Poverty
- Development level
- Age of population
- Location of event
- Time of day
- Depth of focus
- Size of event
- Preparedness
- Precursor events
- Predictability
- Number of aftershocks
- Government stability
- Frequency of events
- Adaptability
Positives of living near volcanoes
- Jobs
- Fertile soil
- Geothermal energy
- Valuable minerals
- Tourist economy
- Can create new land
Negatives of living near volcanoes
- Risk of eruption
- Risk of contaminated water
- Mining can cause noise
- Air and dust pollution
Why do people live in areas at risk of earthquakes?
- Ignorance of risk
- Lack of social memory
- Family
- Place of birth
- People do nothing and accept the risk
- People adjust
Earthquake early warning systems
- Radon levels
- Groundwater levels
- Electrical signals
- Land tilting
- Erratic animal behaviour
- Precursor events
Crater
An approximately circular depression in the ground caused by volcanic activity. It is typically a bowl-shaped feature within which occurs a vent
Vent
Opening in the Earth’s crust from which magma and volcanic gases escape
Secondary vent
On large volcanoes magma can reach the surface through several different vents. Where they reach the surface of a volcano they form a secondary vent
Magma chamber
A large underground pool of molten rock found beneath the surface of the Earth
Risk assess
Judging the degree of danger and destruction that an area might experience as a result of a natural event
Predict
Forecasting future events or changes
Prepare
Finding ways to reduce the possible impacts of natural events
Recovery
The process of rebuilding infrastructure and deciding what needs to be done to restore the disaster are back to normal
Appraise
Reviewing the recovery and assessing how well the emergency operation worked and whether anything more could be done to reduce the impact if a similar event were to occur again
What are some methods of earthquake proofing?
- Cross bracing
- Base isolation - building moves separately to the ground
- Earthquake kit/drills
- Counterweights
- Reinforced windows/window shutters
