Hazards Flashcards
What is a natural hazard?
A natural even or process which affects people, causing loss or injury economic damage etc
What does a natural event need to do to become a natural hazard?
It must affect and involve people, a cyclone in the middle of the pacific that doesn’t affect anyone will remain a natural event
What are the two main types of natural hazard?
Geophysical hazards
Hydro meteorological hazards
What are geophysical hazards?
Hazards that are either caused by inner earth activities or tectonic activities
What are some examples of geophysical hazards?
Volcanoes
Earthquakes
tsunamis
What are examples of geomorphological hazards?
(Hazards involving mass movement)
Landslides
Rockfalls
Rockslides
What are hydrometeorlogical hazards?
Hazards driven by water bodies and the associated weather patterns
What are some examples of hydrometeorlogical hazards?
Blizzards
Droughts
Tropical storms
Hailstorm
Thunderstorms
Floods
Bush fires
Mudflows
Extreme temperaturs
What are the six main reasons people live in areas with natural hazards?
Unpredictability
Lack of alternatives
Russian roulette
Cost vs benefit
Changing levels of risk
Fatalism
Why does unpredictability mean some people live in disaster related areas?
It’s not always known when or where an event will take place and it’s difficult to know the magnitude do it
Human activity and physical changes can increase chances and magnitudes of hazards
Why does lack of alternatives mean some people live in disaster related areas?
Difficult to uproot and move to another location for many, giving up land and employment may be tough
Often the most vulnerable are the poor who are forced to live on fertile volcanic lands or flood plains to survive economically
Why does changing level of risk mean some people live in disaster related areas?
Deforestation and other human activity’s can make areas previously safe at risk, as well as the effects of global warming
Why does a Russian roulette attitude mean some people live in disaster related areas?
Many optimists turn a blind eye believe that disasters are acts of god and will not hurt them
Many look at statistics that show people are more at risk from car accidents or influenza than natural hazards
Many also believe if a high magnitude event occurs they will be safe for a number of years but this is not always true
Why do cost vs benefit mean some people live in disaster related areas?
Many hazardous areas offer advantages that others do not
-e.g fertile flood plains
-rich volcanic soils
-beautiful mountainous landscapes
-volcanoes forming tourist opportunities
What is fatalism?
The belief that hazards are natural events people have little control of, and that losses must be accepted
Many think disruption of natural process will destroy nature
What is prediction and how can it reduce impacts of hazards?
As technology improved there are not, sophisticated methods of predicting hazards such as remote sensing and seismic monitoring. Advances in communication can also reduce the effect of hazards through putting warning systems in place when disaster may strike
What is adaption?
Adaption involved living with and changing our behaviour to reduce the severity of natural hazards, this is sometimes cost effective and the most realistic option for most people
What are the four stages of the hazard management cycle?
Mitigation ->
Preparedness ->
Response ->
Recovery
What is mitigation in the hazard management cycle?
This is the first stage of the hazards management cycle that are actions aimed at reducing the severity of future hazards examples include :
Improved building design
Barriers
Long term natural protection like coral reefs (which are the most desirable methods of mitigation)
What is preparedness in the hazard management cycle?
The second stage of the cycle, it involves improving public education and public awareness - it adjusts human behaviour to help minimise the impacts of a hazard. Knowing what to do in the aftermath of an event speeds up recovery
What is response in the hazard management cycle?
The third stage of the hazard management cycle, involves the effectiveness of the management plan put in place to save lives in the result of a hazard
What is recovery in the hazard management cycle?
The final stage of the hazard management cycle, it involves restoring the affected area to normality
What model depicts the typical response to a hazard?
The park model of human response to hazard
What are the 3 phases of the Park management cycle?
Relief
Rehabilitation
Reconstruction
What is the relief phase of the park model and how long after the hazard event is it?
the immediate local and global response in the form of aid, search and rescue and expertise, it usually takes place within hours/days
What is the Rehabilitation phase of the park model and how long after the hazard event is it?
In this phase, services and infrastructure are restored to allow the reconstruction phase to begin, it usually lasts days to months and sometimes years, depending on the magnitude of the hazard.
What is the reconstruction phase of the Park model?
Restoring the same, or better quality of life as before the event took place, this would likely include increased mitigation capabilities to reduce the impact a similar disaster would happen in the future.
How can a disaster affect QoL in the long run (sometimes)?
It can sometimes lead to an improved quality of life as capacity to cope will increase.
What is the true shape of the earth and why?
Earth is a geoid that bulges around the equator and flattens at the poles, because centrifugal forces generated by the earth’s rotation pushing the semi molten material outwards.
What is the basic structure of the earth?
Inner core (1200km)
Outer core (2250km)
Mantle (2900km)
Crust (5-70km)
What are the characteristics of the inner core?
-Solid ball of iron/nickel
-Very hot due to pressure and radioactive decay (contains
elements such as uranium)
-This heat is responsible for Earth’s internal energy, and it
spreads throughout
- The internal heat generated in the core generates convection currents which spread slowly in the Asthenosphere.
What is Primeval heat?
Primeval heat = Heat generated in the core that is retained from when the earth was a ball of gas and dust.
What is Radioactivity in the context of the earths core heat?
The greatest source of internal heat that originates from the natural radioactive decay of Uranium, Thorium and Potassium to create a continues but slowing decay of heat.
What are the Characteristics of the mantle?
-Mainly solid, rocks high in silicon
-The top of the mantle is the asthenosphere
-The deeper down in the mantle you go, the denser it becomes
-2900km thick
What are the characteristics of the outer core?
-Semi-molten
-Iron/nickel
What is the asthenosphere?
The upper layer of the earths mantle, below the lithosphere, it can move very slowly, moving the Lithosphere on top
What is the Lithosphere?
the rigid outer part of the earth, consisting of the crust and upper mantle, it is the zone where tectonic plates are formed.
How do convection currents form?
Hot rock that is heated by the earths core rises,
Nearer the surface the rock is spread in two opposite directions,
The rock begins to lose heat as it nears the surface,
The cooler rock then sinks back down,
This causes the earths crust to slowly be dragged apart, causing continental drift and moving tectonic plates.
What are the two types of crust?
Oceanic and continental crust.
What is the oceanic crust and what is it made up of?
It is an occasionally broken up layer of Basaltic rocks known as SIMA (as they are made up of Silicon and Aluminium)
What is the continental crust and what is it made up of?
Bodies of Mainly Granite rocks known as SIAL (as they are made up of Silicon and Aluminium)
What is Sial?
The upper layer of the earths crust and forms the continental land masses
What is Sima?
Sima is the lower layer of the earths crust and its found beneath the oceans.
What is thicker the Sial or Sima layer?
Sial (continental) is thicker than Sima (Oceanic)
What is denser Sima or Sial?
Sima is denser (like how oceanic plates are denser and subduct)
What is gravitational sliding?
The process of gravity affecting how tectonic plates move, two types made up of slab pull and ridge push (it explains why tectonic plates move, as convection currents alone aren’t strong enough to do this)
What is ridge push?
The slope created when plates move apart
has gravity acting upon it as it is at a higher
elevation. Gravity pushes the plates further
away, widening the gap
What is slab pull?
When a plate subducts, the plate sinking into
the mantle pulls the rest of the plate (slab)
with it, causing further subduction.
What are the 3 types of plate boundaries?
Destructive
Constructive
conservative
What is a destructive plate margin?
When two plate boundaries collide head on.
What is a constructive plate boundary?
When plates diverge apart
What is a conservative plate boundary?
When plates silde past each other
What happens when an oceanic plate collides with a continental plate on a plate margin?
Continental and oceanic:
● Denser oceanic plate subducts below
the continental.
● The plate subducting leaves a deep
ocean trench.
● Built up pressure from the melting
plate cause explosive volcanoes
bursting through the continental plate
what happens when two oceanic plates collide on a destructive plate margin?
Continental and oceanic:
● Denser oceanic plate subducts below
the continental.
● The plate subducting leaves a deep
ocean trench.
● Built up pressure from the melting
plate cause explosive volcanoes
bursting through the continental plate
What happens when two continental plates collide on a destructive margin?
● Both plates are not as dense as
oceanic so lots of pressure builds.
● Ancient oceanic crust is subducted
slightly, but there is no subduction of
continental crust.
● Pile up of continental crust on top of
lithosphere due to pressure between
plates.
● Fold mountains formed from piles of
continental crust
What happens when two oceanic plates diverge?
● Magma rises in between the gap left
by the two plates separating, forming
new land when it cools.
● Less explosive underwater volcanoes
formed as magma rises.
● New land forming on the ocean floor by
lava filling the gaps is known as sea
floor spreading (as the floor spreads
and gets wider).
What happens when two continental plates diverge?
● Any land in the middle of the separation
is forced apart, causing a rift valley.
● Volcanoes form where the magma
rises.
● Eventually the gap will most likely fill
with water and separate completely
from the main island.
What happens at a conservative plate boundary?
Between any crust, the parallel plates move in
different directions or at different speeds.
No plates are destroyed so no landforms are
created, but the build-up of friction and its sudden release of energy can lead to earthquakes.
What are the three different types of earthquake?
Shallow focus
Intermediate
Deep focus
How deep is the focus of each earthquake?
Shallow focus (0-70km deep)
Intermediate (70 - 300km deep)
Deep focus (300 - 700km deep)
What are magma plumes?
If radioactive decay within the earths core is concentrated, hotspots will form around the core, these hotspots created localised thermal currents where plumes of exceptionally hot lava rise. AS the hotspot remains stationary, the movement of tectonic plates above it results in the formation of an island chain of active volcanoes that become extinct as the plates move away from the hotspot.
What key factor does the destructiveness of a volcano depend on?
The volcanoes’ viscosity (runniness)
What is the difference between high and low viscosity?
Low viscosity = Runny magma = creates a shallow sided volcano
High viscosity = Thich sticky magma = creates a steep sided volcano
More viscous = deadlier volcano, as lava is more thick and prone to blockage, building up pressure
What three things affect viscosity?
Temperature
Silica content (silicon dioxide)
Volume of dissolved gases
How does temperature affect the danger of a volcano?
The hotter the temperature, the less viscous and more runny a volcano becomes, the magma is very hot, runny and buoyant and as a result don’t block the vent, making them less deadly the higher the temperature is.
How does Silica content affect the danger of a volcano?
The higher the Silica content the thicker the magma (and more dangerous the volcano as it blocks vent)
Liquid rocks with high silica content are colder and therefore are more very viscous, so they block up the main vent, which can trap gasses which produce violent explosions.
How does the volume of dissolved gasses affect the danger of a volcano?
The higher the dissolved gas content, the less viscous the magma is, meaning higher volume of dissolved gasses in magma, making it more runny, making explosions less violent
What is the troposhere?
The lowest layer of Earths atmosphere
What are the three types of magma in ascending order of silica content
Basaltic
Andesitic
Rhyolitic
What are the Characteristics of basaltic magma?
- Below 52% silica content (low viscosity and runny)
- High temperature (more dissolved gasses and more runny)
- Easily releases gasses so less violent eruptions
- Runny lava means low cones and plumes of gasses that are unlikely to breach the troposphere
- lava spreads far from volcano so a wide based, cone volcano is formed.
What are the characteristics of andesitic magma?
- Between 52-68% Silica content
- High eruption columns spread gasses far as it penetrates the troposphere
- eruption column can often collapse causing pyroclastic flows
What are the Characteristics of Rhyolitic magma?
- Above 69% silica content
- high silica content means thick magma, forming a viscous thick magma that cools and blocks the main vent, plugging it and trapping gasses so there is a large build up until they are released potentially through a secondary vent
- produces violent and dangerous eruptions due to their high viscosity
How is Basaltic magma formed?
Basaltic magma are formed by the melting of oceanic crust and the mantle so occur at constructive plate margin.
How is Andesitic magma formed?
Andesitic magma is formed when rising basaltic magma moves with continental crust before it reaches the surface - increases silica content, it is largely formed a t subduction zones
How is rhyolitic magma formed?
Rhyolitic magmas with a high silica content are formed when continental crust melts and so form at plate boundaries involving 2 continental crusts.
What are the 5 primary impacts of a volcanic hazard?
Ash
Lava Flow
Pyroclastic flows (nueese ardentes)
Tephra
Gas
What are the 5 secondary impacts of a volcanic hazard?
Acid rain
Climate change
Flooding (Jokulhlap)
Tsunami
Lahar
What is Tephra?
Tephra is a fragmental metal produced by a volcanic eruption, no matter how big or how the volcano was formed. these fragments are airborne and they fall and rmain as Tephra, unless they are hot enough to become Pyroclastic flows
what are the different forms and sizes of Tephra?
Ash (particles smaller than 2mm in diameter)
Lapilli(between 2 and 64mm in diameter)
Volcanic bombs (anything larger than 64mm in diameter)
What are Lava flows an example?
Lava flows are large deposits of lava that flow down the side of a volcano during a n eruption, an example of this is the lava flow that occurred on the canary island of la Palma
What is Pyroclastic flow/neues ardentes?
A fast moving current of hot gas, ash and volcanic bombs that sweep down sides of volcanoes at around 100mph, they form when columns of erupted material collapse.
An example of this is what occurred at the island of Montserrat at the Soufriere hills volcano.
What is a lahar/mudflow?
A lahar is a hot or cold mixture of rock fragments that flow quickly down the slopes of a volcano, moving up to 40 mph and reaching up to 50 miles away from the volcano. an ecapmle of this is the lahars of mount pinatubo in the Philippines.
What is gas release in a Volcano as a primary impact?
Volcanic eruptions release deadly gasses that can be fatal, like the village of subum in NW Cameroon where over 2,000 people died to volcanic gasses released from the nearby volcano.
After the 1783 eruption of Laki, Iceland, that emitted over 8 million tons of fluorine, the fluorine combined with ash where it fell to earth and was eaten by cattle and livestock. It killed80% of Iceland’s sheep and 50% of cows and horses, as a result the population starved to under 10,000 people, killing 1/4 of the population.
What is the VEI and its criteria?
Volcanic explosivity index, it measures the:
-Eruption rate
-Volume of erupted material
-height of erupted column
- Duration of continuous blast in hours.
what is the scale of the VEI?
Goes up by a unit of one by it goes up by a magniude of 10x
What are the different types of Volcano (6)?
Fissure
Shield
Dome
Ash-cinder
Composite/stratovolcano
Caldera volcano
What are the warning signals of an eruption more formally known as?
Precursors.
What are the different ways of predicting a volcano?
- Ground deformation, if the ground physically rises, it may mean magma underneath is rising, it can be measured using remote sensing and gas
- Seismicity, small low magnitude shallow magmatic quakes can mean magma is rising and a volcano is incoming, measured with a seismometer.
- Changes to gas emissions, Sometimes before an eruption, there may be increased levels of sulphur or CO2 is a sign a volcano is active.
- Hydrology - the acidity of water can be measured and can detect an increase in sulphur dioxide or CO2
What % of Quakes happen on plate boundaries?
90% occur on plate boundaries, 10% occur not on boundaries, called intraplate eqrthquakes that are usually very small
What is the Richter scale?
A measurement of earthquakes which gives a measure of energy of the quake, the amplitude of the wave on a seismometer measures the energy released, every 1 unit up is 10x the energy. But it can be unreliable and it doesn’t measure destruction.
What is the moment magnitude scale?
This is typically more accurate than the Richter sale (which undervalues anything above a six) the MMS or Mu is based on the total moment release of the earthquake. The distance a fault moved and the force required to do so is the moment. This is used more often by seismologists and it increases in units by a factor of 32x rather than 10
Where is Mount Ontake?
Located in centeral Japan on the island of Honshu, 200km west of Tokyo
What are some key facts about mount Ontake?
It is 3067m tall, making it the 2nd tallest Volcano in Japan
It is a very scared place, making it a popular tourist destination
Despite constant monitoring it was thought to be dominant since 1979
Erupted 27th of september 2014.
Why was the Volcano particularly deadly?
Despite constant monitoring it was though dormant since 1979
the minor earthquakes signalling an earthquake were not present
It erupted without warning while over 250 tourists were on the flanks of the volcano
Only 10-20% of the hikers on Ontake had registered that they were there, making t difficult for authorities to determine how many were missing
Rescue efforts had to be abandoned tow days after they had begun due to high levels of hydrogen Sulphide and further rescue efforts were halted when on October 5th when typhoon phanfone hit the region
What was Mount Ontake on the VEI?
3 on the VEI, but its proximity to hikers made it a deadly threat
What was the cause of the eruption and what happened during the eruption?
Water seeped into the Volcano and superheated the magma which then erupted hot ash, rocks and steam
As result, Tephra barrelled down the slopes.
What were the impacts of the Ontake eruption?
At least 57 died and many more injured with cuts and brusises but others lung damage
What is the Mercalli scale?
A measure of how much damage an earthquake causes. It is measure from I -> XII (in Roman numerals)
a XII means everything flattened
VIII means walls collapse and buildings damaged
V means people wake from sleep and suspended objects move
The scale is subjective and not based on fact
What is the Focus of an earthquake?
The point where friction is built up and released in the ground, sometimes known as the hypocentre.
What is the epicentre?
Thee point directly above the focus/hypocentre, generally the closer the epicentre the more the damage.
What is an earthquake?
A sudden and intense period of intense ground shaking caused by the sudden release of energy underground.
What is the Benioff zone?
Found along the subduction zone which results from an oceanic crust being thrust underneath the continental crust.
What are the 4 types of Seismic waves?
Primary waves
Secondary waves
Raleigh waves
Love waves
What are the two body waves?
P waves
S wave s
What are the two types of surface waves?
Rayleigh waves
Love waves
What is a P waves?
A primary wave is the fastest waves to reach the surface and are detected first,
- Have a high frequency
- Push through the core and mantle
- High frequency with compressions
- Go through solids and liquids
What is an S waves?
- Travel only through solids
- Shake through the crust and mantle only
- Half as fast as P waves
- shake like a rope
What is a Rayleigh wave?
- surface wave
- radiate from the epicentre
- low frequency
- travel slower than body waves in a rolling motion causing more damage
What is a Love wave?
- Love waves are the slowest and deadliest type of wave
- They shear the ground faster at right angles
What are the primarty impacts of earthquakes?
- Ground displacements (earthquakes and shockwaves)
What are the secondary impacts of Earthquakes?
- Liquefaction
- Landslides
- Tsunamis
- Fires
- Built environment damage
How many people a year die from earthquakes and what is the biggest cause of this?
63,000 people die a year from seismic hazards , with 75% of these deaths occurring from collapsing buildings.
What is Liquefaction?
Loose sediment shakes while loose water is brought up from the surface, the bearing weight of the ground collapses, casing cars and other objects to sink into the ground, before it then sets again, trapping things into the ground.
What are landslides?
Occur in steep sided relief areas, cliffs are in equilibrium and any amount of shaking causes it to collapse, causing sediment to barrel down the hill.
What are Avalanches?
On mountainous terrain, shaking displaces snow and causes it to roll down a hill.
What are Tsunamis?
Coming from the Japanese word for harbour wave, Tsunamis occur at subduction zones on destructive plate margins, where on plate is subducted under the other before pressure is built up and one flicks upward, displacing water and creating a Tsunami.
What are the characteristics of a Tsunami?
Have a very long wavelength, usually 3 or 4m high, but as waves reach shallow waters, friction makes the waves slow, but make them get taller, known as wave shoaling.
What are fires (secondary impacts to earthquakes)?
Fires are common after Earthquakes, as they often cause gas leaks or electrical fires that are often very deadly as water mains have likely burst and firefighters can’t do their job.
What are the short term responses to an earthquake (lots)?
- emergency aid
- Search and rescue
- Medical attention
- Field hospitals
- Shelter
- Water
- Food
What is the long term response to Earthquakes?
Rebuilding
What are the 4/5 types of management?
- Preparation
- Mitigation
- prevention
- adaptation
- prediction
How can earthquakes be somewhat predicted by?
- Monitoring groundwater levels
- Release of Radon Gas
- Unusual animal behaviour
- Analysing past events
- Local magnetic fields
What are the ways of preventing an earthquake?:
There currently is no way to prevent an earthquake.
What is the FEMA in the USA?
The federal emergency management agency, it has the following earthquake objectives:
- Promote the understanding of quakes and their effects
- to better identify quake risks
- to improve earthquake resistant design and construction techniques
- To encourage the use of earthquake safe policies.
How can buildings be designed to become earthquake resistant?
- putting a large counter balance/concrete balance on the top of buildings which in aid of a computer program move in the opposite direction of the force of an earthquake, like in Taipei 101 in Taipei, Taiwan
- Putting large rubber shock absorbers in the foundations of a building
- By adding cross bracing to a structure, helping it hold better in an earthquake
- reinforced lift shafts with tensioned cables
- reinforced foundations deep in bedrock
- Older buildings can be retrofitted to make them earthquake resistant
How can education reduce the impact of an earthquake?
Instructions can be issued by authorities on how to prepare for an earthquake and what to do during and following one, information like how to secure homes, and assembling earthquake kits. Children and workplaces can have earthquake training drills, in Japan, they have a nationwide disaster prevention day to mark the anniversary of the 1923 Tokyo earthquake (that killed 140,000 people)
In America, the red cross has issued a list of supplies people need in case of a quake, including 3 days of water supplies, food clothing, bedding, fire extinguisher etc.
What methods of fire prevention can be used to minimise the effects of an earthquake?
Smart meters that cut off the gas when seismic activity has been recorded are available.
In Tokyo, the Gas pipelines have a network that transmit seismic data which allows workers to switch off major gas lines after an earthquake occurs.
How can the emergency services mitigate the effects of an earthquake?
They need careful organisation for a a crisis, as it may take days for trained professionals arrive, so basic training for them needs to be provided.
How can Land use planning reduce the impact of an earthquake?
The most hazardous areas in an event of an earthquake can be identified and then regulated in terms of land use, for example, important structures like hospitals and schools need to be built in areas of low risk. It is important to also have a wide open space available often, so that there is a zone safe from fires and aftershocks.
How can Insurance minimise the impacts of an earthquake?
In richer areas, People are urged to take out insurance to cover for their losses, but this is often very expensive and not affordable by most.
How can aid minimise the effect of an earthquake?
Most aid is sent to poorer countries a few days after an event, it includes sending mdeicine, shelter and purification equipment.
What is Tsunami protection and how does it minimise the impact of earthquake?
Some automated systems use pressure sensors attached to boys to measure the pressure of each sea wave column, which sends of a warning. Some places also have Tsunami prevention walls which are over 12m high but these aren’t usually very effective and are often overrun.
What are the two case studies for contrasting earthquakes?
Chile and Haiti
What are the conditions needed for a tropical storm to form?
● Temperature: Ocean temperatures must be around 26 - 27°C to at least 50 metres deep.
● Rotation: Forms around the equator but no less than 5° on either side, this is where the Coriolis force is in full effect and rotates the winds.
● Air pressure: Must be in areas of unstable air pressure - usually where areas of high
pressure and low pressure meet (convergence) - so that warm air rises more readily and
the clouds can form
Where do tropical storms form?
In the Troposhere.
What are tropical storms called in different places?
Pacific = cyclone
Atlantic = hurricane
Indian ocean = typhoon
Describe how tropical storms form?
Tropical storms are found in the tropics between 5 degrees north and 23.5 degrees N/S. They travel in the direction of the trade winds of the Coriolis effect, usually on the west of each ocean. They need ocean temperatures of around 27 degrees C because high temps mean greater evaporation which in turn creates more water vapour and energy. The hot air produced rises, before cooling and condensing as rain, which releases latent heat which warms the air around it, creating a positive feedback loop and explaining why tropical storms lose their energy over land. There also needs to be light cross winds in the upper troposphere that don’t shear the air, to allow the storm to develop.
Why do tropical storms not form on the equator?
Because the Coriolis force doesn’t fully occur around the equator.
What are the Hazards associated with tropical storms?
● High winds - over 300km/h and therefore very strong
● Flooding - coastal/river flooding from storm surges and heavy rain
● Landslides - due to soil becoming heavy when wet with high levels of rain
● Storm surges - Large rise in sea levels caused by low pressure and high winds, pushing
water towards the coast
What are storm surges?
When water rapidly rises up onto land during storm events, high winds push water in front of it onto the land. It can often occur before a hurricane hits, like in hurricane Katrina, which saw storm surges of 6-8 meters.
What makes storm surges particularly troublesome?
A storm surge in conjunction with high tide will be much more dangerous
Because they hit before hurricane it can make evacuation dangerous and difficult to do
It may become worse due to rising sea levels.
Storm surges can occur in places that don’t get hurricanes, and as a result hit many areas that are unprepared for a storm surge.
What factors does the impact of a storm surge depend on?
-Shape of coast
-Central pressure
-angle of approach
-size
-shape of coast
How are tropical storms measured?
Measured on the Saffir-Simpson Scale (A scale of 1-5) based on sustained wind speed
and thus power of the storm (Typhoons do not use the Saffir Simpson scale)
How fast do sustained wind speeds need to be for a hurricane to exist?
Hurricanes are 74mph + wind speeds to make it a cat 1 hurricane.
Why is the Saffir Simpson scale not always fully representative of what a storm is like?
Rainfall, windspeeds and storm surges all create impacts, but the SS scale only takes into account windspeeds.
What is the frequency of tropical storms?
Northern Hemisphere from June-November, Southern Hemisphere from
November-April. Tropical storms are becoming more powerful, but it is not yet known whether they are increasing in frequency.
How predictable are tropical storms?
Tropical storms form away from land meaning satellite tracking of cloud
formations and movement can be tracked and the general route can be
predicted.
What do computer models suggest about tropical storms?
That globally, less storms may occur, but they will be of higher magnitude
The frequency of rainfall in tropical storms will be greater
Eustatic sea level change could mean storm surges may be worse
The spatial distribution of Tropical storms will be more varied
What are the two tropical storms case studies?
Cyclone Winston
Super storm/hurricane sandy
What are the 4 main ways of reducing the impact of a tropical storm?
Preparedness
Adaptation
Mitigation
Prevention
In what ways can people be prepared for tropical storms?
- Awareness of what to do during a tropical storm
- Evacuation plans and disaster training (in Florida evacuation centres and shelters have been signposted which are crucial in saving lives)
- It is now very possible to capture tropical storms with satellite imagery, and warnings can be issued very early.
- The national hurricane centre in the US uses a computer model called SLOSH to estimate storm surges heights, using historical data and using storm characteristics to estimate wave height within 1-20% accuracy
- a cone of accuracy can be used to predict the rough route of a tropical storm.
What are the ways of preventing tropical storms?
Tropical storms cannot be prevented with current technology.
What are the ways to mitigate the threat of a tropical storm?
-Search and rescue, immediate aid, etc
- clearing loose debris before storms
- Possible to reduce storm surges impacts by planting trees, building up walls or beaches
- Structural protection for the home, strengthening the home with barricades and flood protection measures
- Insurance can be claimed to minimise the financial impact of a storm.
What are the ways to adapt to a tropical storm?
-Move away from areas at risk
- Designing buildings that can withstand flood damage and on higher land (land use zoning)
- flood defences like houses on stilts, costal walls and levees etc.
What is a Wildfire?
A large, uncontrolled fire that quickly spreads through vegetation.
What conditions are needed to favour (intense)Wildfires?
-Vegetation Type
Thick, close together vegetation allows fires to spread quickly and easily. Trees and thick
bushes lead to more intense wildfires; grasslands do not burn as intensely. Vegetation with
flammable oils - like eucalyptus - causes more intense fires also.
-Fuel Characteristics
Vegetation should be dry to allow it to catch. Finer vegetation causes fires to spread quicker, but
larger, thicker forms of vegetation burns for longer and more intensely.
Climate and Recent Weather
-Must be in a climate that has enough rainfall to have sufficient plant growth , but considerable
dry spells and droughts to dry out the fuel . Areas with dry seasons such as California allow for
intense wildfires. Wind also causes fires to spread quicker. Recent temperature increases have
caused an increase in the number of wildfires.
-The moisture content of vegetation must be low
- Conditions favouring lightning storms
- Strong dry wind blowing in from continental interiors or deserts exacerbate this
What are the natural causes of wildfires?
Lighting being the biggest cause, but also volcanoes
What are the Human causes of wildfires?
Lit cigarettes
BQQS
Train lines
Agriculture
car sparks
Arson
What is the Ladder effect?
The process by which fire spreads from the forest floor to the tree canopy.
What is a crown fire?
A fire which spreads across tree canopies
What is a Surface fire?
A fire which spreads across surface vegetation
What is a ground fire?
A fire that burns beneath the ground in dry and organic peat.
What is a small example of a bushfire?
Black Saturday, Victoria Australian 2009.
What are some key facts about the Black Saturday Bushfires, Victoria, 2009?
173 people killed
400 and over injured
450,000 Ha burned and 3,500 structures destroyed
temps above 40 degrees
humidity low
winds up to 80mph
two days of raging fire originating from both natural and human causes
What are the two big wildfire case studies?
Fort MacMurray, Alberta Canada
Paradise fire California.
What are the 3climate and weather conditions that can increase wildfire frequency?
Santa Ana Winds
El Niño (and la Nina)
IOD (Indian ocean dipole)
Where do the Santa Ana winds occur?
California
How are the Santa Ana winds form?
Desert winds from Nevada from a clockwise flow of air around a high pressure system east of the sierra Nevada mountains
The air from the mountains is compressed and warmed as it travels downhill, losing humidity and drying out vegetation and fanning fires
Winds squeeze through canyons and valleys at high speeds (65 - 95 kph)
Strong wind speeds create turbulence and spread fires faster.
Where is the El Niño phenomenon located?
Over the pacific from Australia, Papua new guinea to California, Peru etc, occurs every six to eight years
How doe El Niño and La Nina increase wildfire intensity?
El Niño (warm phase) and La
Niña (cold phase) are also
climatic events that are thought
to affect wildfire prevalence. The
effects of these phenomena vary
throughout the world, but in
California El Niño is thought to
provide warmer, wetter seasons
to grow vegetation, and La Niña’s
dryer seasons create more
wildfires
What does a La Nina year cause?
Lots of flooding and wetness on the east coast of australlia
while southern USA becomes colder but drier
What is the IOD and what did it coincide with?
The Indian Ocean Dipole occurred at the same time as the Australia black Saturday wildfires.
What happens during a positive IOD phase?
During a positive IOD phase, it is cooler in the east and warmer in the west, There is a decrease in rainfall over central and southern Australia.
What are the Primary Environmental impacts of a wildfire?
Destruction of habitats and ecosystems
Death of animals and plants disrupting food chains and food webs
Short term surge of Co2
Atmospheric pollution from smoke and water pollution occurs as toxic ash gets washed into water sources.
What are the Secondary Environmental impacts of wildfires?
Lack of trees and vegetation causes depletion of nutrient stores, increased leeching and increased risk of flooding
Increased carbon emission have impacts on the greenhouse effect and climate change
Effects on ecosystem development known as secondary succession.
What are the social impacts primary of wildfires?
Loss of life + Injury
Displacement of people as they are temporarily forced to live elsewhere
Disruption to power supplies as power lines are damaged by wind
Damage to mobile phone stations and telephone communications, harming communication
What are the social impacts secondary of wildfires?
Possible need for new income sources and employment streams
Behavioural adaptation based on wildfire experience, people may need to adhere to new rules and regulations.
What are the Economic Impacts primary of wildfires?
Damage or destruction of structures
Financial loss
Destruction of businesses
Loss of crops and livestock
What are the economic impacts secondary of wildfires?
Cost of rebuilding and relocation
Replacement of infrastructure, mainly agricultural industry
Cost of future preparedness and mitigation strategies
What are the political impacts primary of wildfires?
Actions of emergency services
Responses of local and international governments
Pressure on local authorities and emergency services to coordinate aid and prioritise responses in the immediate aftermath
What are the political impacts secondary of wildfires?
Development of strategies for future mitigation
Decisions about replanting forests, regulations and compensation
Review of laws and advice regarding the use of the countryside
What are the global impacts of wildfires on Ecosystems?
Local ecosystems affected with habitats destroyed, animals killed or displaced and soil nutrient stores depleted
Wildfires affect the development of vegetation succession, causing secondary successions to be initiated in forests and shrubs
Nutrient cycles impacted as biomass and litter stores are burnt
What are the global impacts of wildfires on Water?
Loss of vegetation affects the water cycle, reducing humidity (less transpiration) and altering the relative significance of transfer processes like runoff, evaporation and infiltration
Toxic ash can flow into water courses adversely affecting aquatic environments.
What are the global impacts of wildfires on Greenhouse effect?
Burning will release the carbon stored in trees, plants and peat, this increase the Co2 in the atmosphere, enhancing the greenhouse effect and creating a positive feedback loop as increasing temperatures will increase the likelihood of wildfires.
How can nations prepare for a wildfire?
Many have Rural firefighting forces staffed by volunteers
During times of high fire risk warnings are released and fire bans may be introduced to lower the risk of a fire starting (the USA national weather service offers warning to resident when there is high fire risk (Low humidity, high temperatures, dry fuel, strong winds)
A red flag warning may be issued when there may be an extreme fire in the next 24 hours
a ire weather watch is issued when weather conditions for a fire could be met in the next 24-48 hours
How can individual households prepare for wildfires?
They can make a defensible space around their homme and property to prevent a fire jumping onto their property, but fires can jump up to a whole kilometre, people can also:
- Stack firewood away from home
- Remove leaves and other litter
- Dispose of debris
Prune branches from 10ft off the ground
- Trim branches
- Reduce the density of surrounding forests
- Clean roof and gutters.
How can early fire detection occur?
Using cameras, infrared censors, fire towers and satellite.
What ways can wildfires be mitigated?
-Perimeter of firebreaks can be established, involving the purposeful burning of vegetation in front of the fire front, but natural barriers can lso be used (but these can be jumped by firebrands
- Disaster aid and insurance can mitigate the economic effects of a fire
What is a n example of disaster aid in mitigating the economic effects of a wildfire?
After the black Saturday bushfires in Victoria in 2009,
- The Australian government released the ‘rebuilding together’ scheme which granted $193 million AUD to replace major community facilities and kickstart economic recovery
- They also created a $485 million USD recovery assistance package to address the ‘phycological, economic, infrastructure and environmental impacts’ of the wildfires
What are the methods of preventing wildfires?
Wildfires often need dead litter that has collected on the ground to spread (acting as fuel)
- therefore continued burning can be used to reduce the amount of fuel available for the fire to consume, but there is a danger they will go out of control
- Public awareness can also be used to reduce wildifres frequency, especially in campsites and public areas when lighting fires
- many countries operate fire bans in many countires in conditions that favour wild fires
What is an example of a way wildfires have been preventing?
Since 1944 Smokey bear the cartoon bear has been urging Americans to behave responsibly with fires,
96% of Americans recognise him
70% recall his message
The average numbers of hectares lost in the us has fallen from 54 million in 1944 to 16.5 million today
How can we adapt to Wildfires?
- Planning regulations to reduce the risk of wildfires from human activity
- Building design can also reduce the risk of fire, they need to be cheap, simple and made of natural products so they don’t cause pollution when they burn down
What are the drawbacks of managing wildfires?
However, fires are a naturally regenerative process within a forest , it can help remove older, less productive vegetation, cleaning out all dead brush and allow new, healthier vegetation to grow
Sequoia trees during wildfires dry out sequoia tree cones to open, allowing them to drop seeds
Fires also help increase nutrients in the soil, while also allowing a forest to become more resistant to fire, as there is no extra fuel to burn.
What are Multiple hazard zones?
MHZ’s are also known as disaster hotspots, they are a region or part of the world that can be affected by a range of hazards, which are often a combination of meteorological climate hazards and geomorphic hazards
What are some examples of MHZ’s?
Mexico
California
Windward islands
Bangladesh
Japan
Philippines
How are hazard hotspots identified?
Hydrometeorological hazards
Tectonic or localised geomorphic hazards
Vulnerability
Why is it important to identify hotspots?
As it can create huge implications for development, investment planning, disaster preparation and more.
What is the case study for a local scale of a specified place in a hazardous setting?
The 1995 Kobe / Great Hanshin earthquake
What was the magnitude of the Kobe earthquake?
6.8 on the moment magnitude scale
Why is California a hazard hotspot?
- Lies on a conservative plate boundary on the san Andreas fault
- 35% of the state is pine forest which is prone to wildfires under drought conditions (+ Santa Ana winds and El Niño) and more chaparral vegetation (deciduous trees and shrubs under 2.5m tall that are prone to fires)
- In the mountains and coastal regions landslides occur frequently
- Flash flooding can occur following thunderstorms and snow melt in spring
- man made smog and pollutants
