Natural hazards Flashcards
Define ‘natural hazard’
A naturally occurring event that harms people or has the potential to cause damage
Define ‘tectonic hazard’
A hazard created by the movement of tectonic plates, volcanoes, earthquakes
Define ‘atmospheric hazard’
Created in the atmosphere, hurricanes
Define ‘water based hazard’
Created by rivers or oceans, floods
What makes hazards worse?
Magnitude level of development, climate change and population density
Describe the structure of the earth
Inner core, outer core, mantle, crust
What are the two types of crust?
Oceanic- under the sea, thinner, dense
Continental- under the land, thicker, less dense
Where do earthquakes and volcanoes occur?
Normally along plate boundaries, most volcanoes occur at constructive boundaries, most earthquakes occur at destructive boundaries
What happens at the three different types of plate boundary?
Destructive- oceanic under continental, earthquakes due to friction, volcanoes due to convection currents
Constructive- plates move apart due to convection currents, volcanoes form
Conservative- plates move alongside each other, earthquakes caused by friction
Where is Haiti located?
Haiti is an island located between the north american and Caribbean plate. It is east of Mexico and north of south America, it is a LIC
When did the earthquake occur?
January 2010
What type of boundary is Haiti on?
A conservative boundary
What was the magnitude of the earthquake?
7.2 on the richter scale
What were the social primary effects?
Homes, roads, bridges, building collapsed, 200,000 people killed, 1.5 million people made homeless, 300, 000 injuries
What were the economic primary effects?
The country was unable to afford emergency supplies
What were the environmental primary effects?
There were many fires and landslides as well as tsunamies which ruined the landscape and increased costs
What were the social secondary effects?
Faamine and disease became a large issue as a consequence of low income, disease, cholera etc, people were forced to live in temporary accomodation
What were the economic secondary effects?
There were houses flattened and destroyed which increased repair costs
What were the environmental secondary effects?
There was a fear of future tectonic events which would ruin the land
What were the immediate responses to the earthquake?
Search teams and nurses began to work imediately, world aid began, many countries sent relief, the USA and UN took control over the situation
What were the long-term responses to the earthquake?
Cash-for-work programme, roads repaired, new quake-proof buildings, washing areas built, farmers supported, Haiti appeal to raise funds
What affects the weather?
The atmosphere
How are tropical storms formed?
When the sea is 27°C, they lose energy when the sea reaches the land.
What are the conditions at the eye of the storm?
Calm
What are the conditions in the eye wall?
Violent wind and rain
Why are tropical storms expected to get more intense and more frequent?
As a result of warmer oceans (climate change)
Where did typhoon haiyan occur?
The Philippines (fairly poor), Tacloban was most affected
When did the typhoon occur?
November 2013
What were the social primary effects?
6300 deaths
600000 homeless
What were the economic primary effects?
Tacloban airport badly damaged
Damage to businesses and the work force
What were the environmental primary effects?
5m storm surge caused flooding
What were the social secondary effects?
14 million people lost their source of income
What were the economic secondary effects?
Power supplies were cut off for a month
What were the environmental secondary effects?
Landslides
Where did St.Jude’s storm occur?
Affected the south east of England, it then moved towards the northeast.
When did St.Jude’s storm occur?
October 2013.
What were the social primary effects?
Deaths Drowning Broken gas pipes Power cuts Structural damage
What were the economic primary effects?
Disruption to transport links effected the work and businesses
What were the environmental primary effects?
10 million trees were felled as a result of flooding
Flooding
What were the social secondary effects?
Illness
Flooding and transport disruption stoped people from being able to go out and buy food and supplies
What is the evidence for climate change?
Ice cores, tree rings, shrinking glaciers
What are the naturally occurring causes for climate change?
Changes in the earth’s orbit (MILANKOVITCH CYCLES), solar activities and volcanic activity
How do humans contribute to climate change?
Emitting more greenhouse gases (enhanced greenhouse effect), burning fossil fuels, farming and deforestation
Which methods are used to prevent climate change?
MITIGATION- making changes like sing renewable energy sources, carbon capture (storing carbon underground), afforestation
ADAPTATION- agricultural systems (adapting farming methods, managing water supplies, protecting the coast from rising sea levels
What is weathering?
Weathering is the breakdown of rocks were they are. Erosion is the breakdown of rocks and then being carried away.
What are the types of weathering?
Mechanical- freeze thaw
Chemical- acid rain
Biological- plant roots
What are the three types of erosion?
Hydraulic action (waves hitting rocks), abrasion (scraping), attrition (smashing).
Describe a destructive wave
Weak swash, strong backwash
Cause erosion
Tall and steep
Describe a constructive wave
Strong swash, weak backwash
Short and low
What is long-shore drift?
The movement of material along a coast by waves which approach at an angle to the shore but recede directly away from it.
Define hard-engineering
MAn-made structures built to reduce flooding and erosion
Define soft-engineering
Schemes set up to reduce the effects of flooding and erosion
What is a sea wall?
A wall made of concrete to reflect waves back out to sea
What are the pros and cons of sea walls?
Prevents erosion, prevents flooding
Creates a strong backwash which erodes under the wall, very expensive to vuild and maintain
What are gabions?
Wall made out of wire cages filled with rocks usually built at the bottnm of cliffs
What are the pros and cons of gabions?
Absorb wave energy so reduce erosion, cheap and easy to build
Ugly and wire cages can corrode over time
What is rock armour?
Boulders that are piled up along the coast (sometimes called rip rap)
What are the pros and cons of rock aromur?
Absorb wave energy, reduce erosion and flooding, quite cheap
Boulders can be moved by strong
What are groynes?
Wooden fences built at right anglkes to the coast to trap material and stop longshore drift
What are the pros and cons of groynes?
Create wider beaches which slow waves down, gives better protection from flooding and erosion, quite cheap
Stop sand being taken to beaches furthur down the coast so makes them narrower, narrow beaches don’t protect the coast so greater erosion and flooding elsewhere
What is beach nourishment and re-profiling?
Sand and shingle from elsewhere is added to the upper part of the beach
What are the pros and cons of beach nourishment and re-profiling?
Create wider beaches which slow down waves and give better protection from flooding and erosion
Taking material from elsewhere can kill species, very expensive and has to be done many times overtime
What is dune regeneration?
Creating or maintaining sand dunes by adding plants to stabilise the dunes
What are the pros and cons of dune regeneration?
Sand dunes are a barrier between land and sea, wave energy is absorbed which prevents flooding and erosion, cheap to plant
Protection is only for a small area, very expensive to add sand to dunes
Holdreness coast
Cliffs are made form boulder clay which is very soft, over 1m of land lost every year
Rock armour and groynes in Mappleton, 60,000 tonnes of rock used
Defneces saved MAppleton but caused increased erosion furthur south and led to loss of habitat
Describe the formation of wave cut notches and wave cut platforms
Erosion happens at the foot of a cliff which leads to the formation of a notch, the notch is enlarged as erosion continues, the rock collapses, the material is cleared, a new notch forms, rock collapses, material clears, cliff retreats, wave cut platform forms
Describe the formation of headlands and bays
The coastline is made up of bands of hard and soft rock, the soft rock is eroded more easily, where there are alternating bands of resistant and less resistant rock headlands and bays form
Describe the formation caves, arhces, stacks and stumps
Hydraulic power and abrasion enlarge cracks in headlands, repeated erosion causes a cave to form, continued erosion deepns the cave until it becomes an arch (Durdle door in Dorset), the rock supporting the arch collapses as a result of erosion, this forms a stack, an isolated rock thats separated from the headland is a stack (Old Harry in Dorset), the stack is weakened by erosion and collapses whcih forms a stump.
Describe the long profile of a river
Steep gradient up-stream, very gentle gradient down stream
Describe the river cross section of a river
Upper course- narrow, v-shaped valley, steep, boulders and rocks
Middle course- wide, u-shaped valley, gentle valley sides, stones and pebbles
Lower course- wide valley, flat, smooth and silt
Describe the formation of waterfalls
Waterfalls are formed where a river flows over areas of hard rock followed by areas of soft rock, the softer rock is eroded by hydraulic action and abrasion more than the hard rock creating a ‘step’ in the river, it erodes more and more of the softer rock, the hard rock is eventually undercut by erosion, it becomes unsupported and collapses, the collapsed rock causes furthur erosionat the foot of the water fall by abrasion which causes a plunge pool to form, more undercutting causes mre collapsing which causes the waterfall to retreat which leaves behind a steep-sided gorge
Describe the formation of meanders
Meanders are formed by erosion and deposition, the current is fastest on the outside of the river becasue it is deeper so there is less friction to slow the river down, more erosion takes place on the outside bend which causes river cliffs to form, the current is slower on the inside bend because it is shallower so there is more friction to slow the river down, eroded material is deposited on the inside which causes slip-off slopes to form
Describe the formation of ox-bow lakes
Erosion causes the outside bends to get closer until theres only a small bit of land left between the bends (called a neck), the river breaks through this land, usually during a flood and the river flows along the shortest course, deposition eventually cuts off the meander forming an ox-bow lake
Describe the formation of a levee
Levees are natural embankments, during a flood eroded material is deposited over the flood plain, the heaviest material is deposited closest to the river channel because it gets droped first when the river slows down, overtime, the deposited material builds up creating levees along the edges of the channel
Describe the formation of a floodplain
The flood plain is the wide valley floor on either side of a river which occasionally gets flooded, when a river floods, the water slows down and deposits the eroded material material that it is transporting, this builds up which makes the flood plain higher, meanders migrate across the floodplain which makes it wider, meanders also migrate downstream, flattening out the valley floor, the deposition that happens on the slip-off slopes of meanders also builds up the flood plain
Describe the formation of estuaries
Estuaries are found at the mouth of a river where it meets the sea, the land is close to sea level and the river valley is at its widest, the water here is tidal (moves up and down), the wtaer floods over the banksof the river carrying silt and sand onto the valley floor, as the tide reaches its highest point, the water is moving very slowly so the sediment is deposited, more and more mud builds up which creates large areas of mudflats, at low tide, the wide, muddy banks are exposed
What are the physical (natural) causes of flooding
Raining for a long time- soil becomes saturated, water runs of surface = flood
Heavy rainfall- too much rain arriving too quickly so can’t soak into ground
Impermeable rock- water can’t infiltrate
Steep land- water runs into river faster down steep slopes
What are the human causes of flooding?
Building roads and buildings- tarmac and concrete are impermeable, water runs off the surface
Removing trees- trees can’t soak up water
What are dams and reservoirs?
Dams (huge walls) are built across a river, a reservoir (big lake) forms behind the wall
What are the pros and cons of dams and reservoirs?
Reservoirs store water, reduce risk of flooding, drinking water from reservoir, generate HEP
Very expensive, floods land behind dam, sediment trapped in dam so farmland downstream is less fertile
What is channel straightening?
River is straightened- meanders are cut off
What are the pros and cons of channel straightening?
Water moves out of an area faster
Flooding can happen downstream because it arrives there faster, more erosion because water is faster
What are flood warnings?
Environment agency warn people of the risk of flooding on TV, radio, newspapers and internet
What are the pros and cons of channel straightening?
Impacts are reduced, people can move posessions upstaris, put sandbags out and evacuate
Doesn’t guarentee safety from a flood, people get a false sense of security, people may not hear the warning or have access to them
What is zoning?
Restrictions stop building on parts of the floodplain that are likely to flood
What are the pros and cons of zoning?
RIsk is reduced, no impermeable surfaces, impacts reduced because there are no buildings
Growth of the urban area is stopped, does’t work in areas that have already built on the floodplain
What is planting trees?
Planting in river valley, increases interception and reduces lag time
What are the pros and cons of planting trees?
Discharge and flood risk are reduced, trees reduce soil erosion and provide a habitat
Less land is available for farming
What is an ecosystem?
An ecosystem is a natural environment made up of plants, animals and the environment, it includes the biotic (living) and abiotic (non-living) in an area
What is a producer?
Producers convert energy from sunlight to produce food
What is a consumer?
Consumers get energy from eating either producers or other consumers
What is a decomposer?
When dead material is decomposed, nutrients are released into the soil
What is a food chain?
A food chain shows what eats what in an ecosystem, a food web is a more complex picture of food chains and how they overlap
What is nutrient cycling?
Nutrient cycling is when nutrients are tranferred throughout the ecosystem between organisms
Why is balance important in ecosystems?
Changing one part of an ecosystem will affect all the other parts, the changes could be natural (climate change) or human (eutrophication)
What are biomes?
Large scale global ecosystems, they are found it broad belts from east to west, parallel to the lines of latitude, the vegetation and climate vary due to atmospheric circulation nad how close they are to the equator (rainfall and temperature).
What are tropical rainforests like?
High temperatures, heavy rainfall
Global distribution- close to the equator
What are tropical rainforests like?
High temperatures, heavy rainfall
Global distribution- close to the equator
What are hot deserts like?
Low rainfall, high daytime time, low nighttime temp
Global distribution- 30° north and south of the equator
How are plants adapted to tropical rain forests?
Tall trees to reach the sunlight
Drip tip, waxy leaves so water drains off
Thick buttress roots to hold tall trees steady
Wide root network to get nutrients from he soil
Climbing plants (lianas) which use tree trunks to get to light
How are animals adapted to tropical rain forests?
Prehensile (gripping tails) to live in the canopy (eg howler monkey) Camouflage to hide in he shrub layer Suction pads o feet to grip in trees Nocturnal to avoid heat of the day Strong bills on birds to crack nuts
What is biodiversity?
Biodiversity is the variety of plant and animals species in an ecosystem, it is high in tropical rain forests, tropical rain forests contain 50% of the species
What is happening in the Amazon rain forest in South America?
750,000 km^2 of the forest has been deforested
Why does deforestation happen?
Commercial cattle farming (65-70%), small scale subsidence farming (20-25%), commercial farming, logging, other activities including mining, urbanisation, energy- hydroelectric dams ad reservoirs (2%)
What are the positive social impacts?
Creates jobs for local people, economic growth from selling goods $6.9 billion in 2008 in Brazil, taxes being paid to improve public services, hydroelectric power is cheap and renewable
What are the negative social impacts?
Destroys livelihoods of indigenous people
What are the negative environmental impacts?
Loss of biodiversity, increase in CO2 i the atmosphere which leads to climate change, soil erosion leads to flooding and landslides, soil fertility decreases (no canopy to protect the soil and nutrients wash away), pollution from industries
What is being done to protect the tropical rain forest?
Strategies include: selective logging and replanting, conservation and education, tourism and international agreements, debt reduction
What are the characteristics of tundra and polar environments?
Cold, low rainfall, layer of permafrost, no or thin soil, not very fertile, few plants which grow slowly and are short, few species or animals, some areas are almost uninhabitable, tundra have a range of indigenous tribes
How are plants adapted to cold environments?
Some dormant cold winters, cushion-like to protect and insulate themselves, short stems to keep warm, waxy leaves to reduce water loss, low roots, short growing season
How are animals adapted to cold environments?
Well insulated with thick fur or blubber (eg seals), hibernate to conserve energy in winter or migrate (eg arctic terns), white fur for camouflage, adapted to survive on limited food
What is biodiversity like in cold areas?
Biodiversity is low in cold areas, there are fewer species so small changes have a big impact on others
Where is Alaska located?
Alaska is located to the north west of Canada
What are the development opportunities in Alaska?
FISHING- 78,000 jobs, $6 billion to the US economy
MINERAL EXTRACTION- gold, silver, zinc
TOURISM- 1-2 million visitors per year
ENERGY- hydroelectric and geothermal but mostly oil, 90% of taxes come from oil, 400 people employed in the industry
What are the challenges in Alaska?
EXTREME TEMPERATURES: dangerous, difficult to work outside, special clothing required, challenges of construction
INACCESSIBILITY: sparsely populated, poor road network, difficult terrain, hard to travel around
BUILDINGS AND INFRASTRUCTURE: provision is difficult and expensive, some buildings collapsing due to melting permafrost
Why should cold environments be protected?
Wilderness areas provide us with scientific knowledge, vital for biodiversity, indigenous people who rely on ecosystem for survival
How ar cold environments being managed?
Use of technology to improve construction of buildings and communication, role of governments (eg USA protection of the arctic entrenched law), international agreements (eg Antarctic treaty) which affects area, conservation groups (eg WWF and Greenpeace) encourage protection for areas
