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Define Disaster
A major hazard that causes widespread disruption to a community that may be unable to deal with the impacts without outside help
Define Hazard
A threat (human or natural) that has POTENTIAL to cause of live, livelihoods or socio-economic disruption
Define Hazard Event
Occurrence of a hazard, the effects which cause demographic, economic or environment changes.
Define Hazard Risk
The likelihood of a hazard causing harmful consequences (loss of lives, livelihoods, property)
Define Vulnerability
The susceptibility of a community to a hazard of the impacts of one.
Name the five types of hazards / Disasters and give an example for each.
Geomorphic - Earthquake
Hydrological - Flood
Atmospheric - Tropical Revolving Storm
Biohazard - Wildfire
Geophysical - Volcanic Eruption
What are the different characteristics of a Hazard?
Magnitude
Frequency
Duration
Spatial Extent
Speed of Onset
Prediction
Impacts / Effects
Define Risk
Probability and quantity caused by hazards that present threats to people
Why do people put themselves at risk to Hazards? Give three reasons
Any three from
Unpredictable
Lack of alternatives
Changing levels of risk
Cost/Benefit Analysis
Perception
Give four factors that affect someone's risk to a hazard
Any four from
Frequency
Size / Magnitude
Distance from the Event
Length of the Event
Timings
Isolation
Level of Development
Geology
Education
Give three factors that affect someone's vulnerability
Any three from
Age
Disability
Population Density
Political Stability
Religion
Values / Personality / Expectations / Employment.
What are the three types of hazard perception?
Fatalism
Adaptive
Fear
Define Fatalism
People choosing to accept that hazards will occur ie "God's Plan". Losses are considered to be fate and people stay.
Define Adaptive
People view they can be prepared and survive hazards, this is often dependant of level of development.
Define Fear
People feel vulnerable to the point where they leave and move to areas where hazards are less likely to impact them
Typically, which hazard perception is more often seen in HIC's.
Adaptive (Fear in some cases)
Typically, which hazard perception is more often seen in LIC's
Fatalism
Define the Hazard Management Cycle
A cyclical method of preparing for each disaster, focusing on before and after the hazard. It involves a number of key stages including, hazard identification, analysis of risks, prioritising greatest risks. Implementing plans, public awareness and monitoring. After an event, infrastructure is repaired and cycle repeats.
What are the Three P's for Disaster Management?
Predict - The Risk
Prevent - Mitigate
Protect - People and Property
Give some advantages of the Hazard Management Cycle
Can be applied to any hazard
Reassures people
Focuses on before the hazard
Easy to understand
Useful to assess pros and cons, what happened vs what should've happened
Give some disadvantages of the Hazard Management Cycle
Certain sections of the cycle are vague
Favours HIC's who have time, money, resources and knowledge.
Define Park's Curve
Shows how a country might respond to a hazard after it has occurred. Time dimensions exist from the beginning of the event to full recovery. Often used to understand resilience and preparation for future events.
There are two types of crust, what are they?
Continental and Oceanic
Give some properties of continental crust
1500 million years or older
Less Dense
Average thickness 35-40km
Indestructible - Doesn't sink
Lighter in colour, mainly granite rock type.
Silica and Aluminium (Sial)
Give some properties of Oceanic Crust
200 million years old or less
Average thickness 6-10km
More dense
Darker in colour, mainly basalt.
Destructible but can be reformed.
Silica and Magnesium (Sima)
What are the four physical layers of the Earth?
Crust, Mantle, Outer Core, Inner Core
How thick is the mantle?
2900km
What are the chemical layers within the mantle?
Lithosphere, Asthenosphere, Mesosphere
Define Lithosphere
Made of crust and solid upper mantle. Divided into lithospheric plates.
Define Asthenosphere
Layer of upper mantle is ductile and can move / reshape slowly.
Define Mesosphere
More viscous (Almost solid) because it is under pressure. Heat is transferred unevenly, leading to plumes and hotspots.
How hot is the core of the Earth roughly?
Around 5000'C
How does the core create the Earth's magnetic field?
The core is made of mostly iron and nickel, which are magnetic. The outer core is also liquid which spins and create the field.
Where is the source of most of Earth's gravity?
Inner Core - Very Dense
Name and define two energy sources of the Earth
Primordial Heat - Heat from the Earth's formation
Radiogenic Heat - Heat from radioactive decay of isotopes in the mantle.
What evidence is there to support the movement of Tectonic Plates?
Jigsaw Theory - Africa and South Africa "fit" together
Similar fossils found on different continents.
Coal being found in Antarctica despite needing warm and wet conditions to form.
Glacial deposits in Brazil that match Western Africa.
Who initially proposed Continental Drift and when?
Alfred Wegener in 1912
Who discovered evidence for Sea floor spreading in 1962 and what was it
Harry Hess - Newer rocks were discovered in Iceland and older ones were located on shores of the Caribbean and the USA.
What method was used to confirm sea floor spreading.
Palaeomagnetism - The study of Earth's magnetic field.
The Earth's Magnetic North and South Poles flip every 400,000 years. Iron Oxide particles preserve the direction of the north pole at the time.
Who discovered the magnetic stripes at the bottom of the Atlantic Ocean
Vine and Matthews.
What are the different forces for plate movement
Convection Currents
Gravitational Sliding Theory
Ridge Push
Slab Pull
Define Convection Currents
Radioactive decay of isotopes creates large temperatures. Hot air rises and forces plates away from each other before sinking. It is not the driving force of plate movement however.
Who proposed the Gravitational Sliding Theory in 1964?
Egon Orowan
Define Ridge Push
The lithosphere thickens with time and distance from the mid ocean ridge. Boundary between lithosphere and asthenosphere becomes deeper and slopes away from the ridge. Gravity acting on the weight of the lithosphere causes it to slide away.
Define Slab Pull
When an oceanic plate becomes so dense, it subducts under it's weight and pulls the rest of the plate along with it.
What are the three different plate boundaries?
Constructive (Diverging)
Destructive (Converging)
Conservative (Transform)
Where do 95% of volcanoes occur at?
Plate boundaries, the remaining 5% occur at intraplate boundaries
Which plate boundaries do volcanoes occur at?
Converging - Lots of Volcanoes (Ring of Fire)
Diverging - Fewer Volcanoes (Typically less explosive)
Transform - NO VOLCANOES
Define Hotspots
Formed by radiogenic heat that is focused on a single location. Plumes of magma rise and burn through thin lithosphere.
Why are there lots of volcanoes in Hawaii?
The hotspot under Hawaii doesn't move, but the plate above does, so volcanoes become extinct when they move away, and new islands are formed. The old ones are eroded.
What is the name of the Hawaiian island that will surface in 200,000 years time?
Loihi
Define Intrusive Volcanic Activity
Activity that occurs inside the lithosphere.
Define Extrusive Volcanic Activity
Activity that occurs on the surface of a volcano.
What is the difference in rock types in intrusive and extrusive activity?
Intrusive activity creates rocks such as granite, extrusive activity creates finer rocks such as basalt.
How does the silica content of lava determine explosivity?
Low silica content means low viscosity meaning less trapped gases. This leads to less explosive eruptions.
Name the three types of lava in order of silica content (lowest to highest)
Basaltic, Andesitic, Rhyolitic.
What is another name for nuees ardentes
Pyroclastic Flows
Name gases that are released from a volcano
Sulphur Dioxide
Carbon Dioxide
Nitrous Oxides
What are the different types of volcanoes
Acid Dome
Caldera
Ash and Cinder
Shield
Stratovolcano
Give some primary impacts of Volcanoes
Wildfires
Buildings destroyed
People / Wildlife Killed
Mud Flows
Give some secondary impacts of Volcanoes
Disease
Respiratory Problems
Further Eruptions
Acid Rain
Landslides
Economic Loss
Biodiversity fall
Volcanic Winter
Looting
Air Travel Disruption (E-15)
What does VEI stand for?
Volcano Explosivity Index
What are the factors to determine the VEI Scale
Volume of Material
Height of Eruption Column
What scale is the VEI Scale?
Logarithmic (Each increase by 1 is 10x greater than the last)
How can volcanoes be predicted?
Any from
Seismicity weeks and days beforehand
Heat emissions years before
Tiltmeters measure the ground
Changing magnetism is an indicator
Rising Magma heats groundwater
Sulphur dioxide levels measured (Degassing of Magma)
Give some methods to mitigate against volcanoes
Risk assessments
Physical structures to divert lava
Education
Communications
Laws
Exclusion zones and evacuation plans
Give some methods to prepare for volcanoes
Evacuation
Boarding up doors and windows
Emergency supplies and documents
Personal Warning Systems (SMS)
Training rescue teams.
Give some responses to volcanoes
Immediate relief, saving lives
Essential services reconnected
Use of technology to find family and friends
Give some methods of recovery to a volcano
Reconstruction of infrastructure
Education
Lessons learnt on perceived risk.
What is the proportion of earthquakes occurring at plate boundaries?
95% - 80% of these occur at the Ring of Fire.
What are three foci of Earthquakes
Shallow Focus (0-70km)
Intermediate Focus (70-300km)
Deep Focus (300-700km)
What magnitude of earthquakes are typically found at the plate boundaries?
Constructive: 1-5
Conservative: 1-7
Destructive: 1-9
Define the Benioff Zone
Benioff Zone is 100-700km below the Earth's surface. Source of medium and deep focus earthquakes. Where oceanic crust is destroyed
Define P-Waves
(Primary / Pressure) Body Wave - Fastest and reach the surface first. They have high frequency. Travel through mantle at 6km/s and core at 13km/s.
Define S-Waves
(Secondary / Shear) Body wave - High frequency, shake like skipping rope. Travel through mantle at 3.5km/s through mantle but not the core.
Define L-Waves
(Love) Surface Wave - Slowest but cause the most damage. Move side to side and originate from the epicentre. Only travel through lithosphere.
Define R-Waves
(Rayleigh) Surface Wave - Radiate from epicentre in complicated patterns. Moving at 0.34km/s
What can seismicity cause?
Ground Shaking
Liquefaction
Tsunamis
Define Liquefaction
Soil saturated with water - earthquake vibrations can cause it to act like a liquid. Soil becomes weaker and deforms / subsides. More likely when something heavy is on top of it.
Define Tsunami
When a plate springs back underwater, it displaces a large amount of water above it which radiates away.
Long wavelength in deep water. friction in shallower water reduces wavelength, so the wave catches up and breaks. Wave can travel hundreds of metres inland.
What are the three different scales for measuring Earthquakes?
Richter Scale
Mercalli Scale
Moment Magnitude Scale
Define the Richter Scale
Logarithmic scale. Theoretically goes on forever, but highest it usually goes for measuring earthquake is 9.0. Highest ever is 9.5 in Chile
Define the Mercalli Scale
Intensity of damaged is recorded through observations on the ground. 12 different strengths (I - Imperceptible to XII - Catastrophic)
Define the Moment Magnitude Scale (MMS)
A scale similar to the Richter scale based on the total energy released by an earthquake. It is more accurate than the richter scale, particularly for large earthquakes
Give ways to predict an Earthquake
Trick question. Earthquakes are very hard to predict because of their chaotic nature.
Give ways to plan for an Earthquake
Procedures already put in place ready for an earthquake
Building design made to stop total collapse
Resistance of forces, diagonal bracing, rigid girders.
Absorbing the sway, taller buildings designed to sway in the shaking.
Services - Flexible piping to reduce damage and fires.
What factors influence the response to seismic activity.
Speed of Onset
Magnitude
Time of day
Building Resistance
Geology of the ground
Proximity
Duration of Shaking
Aid levels
Expertise
Technology available
Population size and density
How much energy in an earthquake is lost in the first ten seconds (%)
95%
What is the name of model involving high and low pressure?
Global Atmospheric Circulation Model
What is pressure measured in, and what is considered high and low pressure?
Pressure is measured in millibars (mb)
High pressure is anything above 1010mb and low pressure is anything below that.
Define high pressure
Cold, dry, sinking air. Leads to clear skies and no precipitation. Often in hot and cold deserts (Rainfall under 250mm per year)
Define low pressure
Warm, wet, rising air. Cools and condenses to form precipitation as rain / sleet / snow. Often in Tropical Rainforests.
What are the names of the three different cells and what latitudes are they at?
Hadley: 0 - 30' N and S of the equator
Ferrel: 30 - 60' N and S of the equator
Polar: 60 - 90' N and S of the equator.
Where do tropical storms occur?
The ITCZ - The intertropical convergence zone. Around 5 - 30' N and S of the equator.
Define the Coriolis effect
The spin of the Earth which is strong enough to rotate tropical storms. West to East in Northern Hemisphere and East to West in Southern Hemisphere.
Why don't tropical storms occur at high latitudes
The Coriolis effect is too strong and the sea temperatures do not reach 26.5'C
Define Tropical Storms
An intense, low pressure weather system that develops in the ITCZ. Sizes of around 200-700km in diameter and need minimum sustained winds of 74mph (120kph)
What factors affect the distribution of tropical storms
Sea surface temperature (26.5'C for 50m below the surface)
Convergence of air in the ITCZ
Coriolis effect
LOW PRESSURE
Uniform wind directions across all levels.
Define the Saffir Simpson Scale
Linear scale with 5 categories dependant on 4 factors
- Central Pressure
- Wind Speed
- Storm Surge
- Damage Potential
What typical factors does a Category 5 tropical storm have on the Saffir Simpson Scale?
920mb central pressure
156+ mph sustained winds
18ft or greater storm surge in one location
Total damage to roofs and most buildings. Lots of damage to all buildings 0-3m above sea level.
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