Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

physical geography > hazards > Flashcards

hazards Flashcards

1
Q

what is a hazard?

A

a hazard is something that is a potential threat to human life or property

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

natural hazard

A

a natural hazard is caused by natural processes e.g. a lava flow from a volcanic eruption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the three types of natural hazards

A
  1. geophysical hazards- caused by land processes- these include earthquakes, volcanoes, landslides, tsusnamis
  2. atmospheric hazards- caused by climactic processes and include cyclones, droughts, wildfires etc
  3. hydrological hazards- caused by water movement e.g. floods and avalanches
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what factors cause people to perceive hazards differently?

A
  • wealth
  • religion e.g. acts of god to punish people
  • education
  • past experience
  • personality e.g. some may find them frightening, some exciting
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the main responses to hazards?

A
  • prevention
  • mitigation- reducing the impacts which could be by prediction or adaptation
  • governments could coordinate responses to manage more effectively
  • fatalism- accept that hazards cannot be avoided
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what does the park model show?

A

the park model shows the different phases of response to a hazard

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are the 5 stages of the park model?

A
  1. pre-disaster before the event, the situation is normal
  2. disruption- during and directly after the hazard event occurs, there is destruction of property, loss of life etc. before people begin to respond
  3. relief- in the aftermath of the event rescue efforts are occurring. this focuses on preventing further damage
  4. rehabilitation- once the immediate impacts are under control, people start to resolve longer-term problems e.g. providing temporary shelter and aid
  5. reconstruction- rebuilding of permanent houses, infrastructure etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

pros of the park model

A
  • can compare to other hazards as it is easy to visualise
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

why is the park model useful?

A
  • can be used to predict future hazards because it shows the progress of the responses of hazards
  • can also prepare for future disasters better because of this and mitigate the impacts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

negatives of the park model

A
  • doesn’t include environmental factors
  • vague. when does one stage start and the next end?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the hazard management cycle

A

The HMC illustrates four stages in the management of hazards in seeking to reduce the scale of a disaster: preparedness, response, recovery, mitigation.

Hazard Management Cycle can be applied to both natural and man-made disasters. This includes events such as earthquakes and hurricanes, or industrial accidents and terrorist attacks. The cycle’s purpose is to prevent, prepare for, respond to, and recover from any disaster.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the 4 stages of the hazard management cycle?

A
  1. mitigation
  2. preparedness
  3. response
  4. recovery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

pros and cons of the HMC

A

pros:
simple and easy to use

cons:
vague. no length of time being put on it so don’t know how long each stage takes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

aerial extent of a hazard

A

the damage caused by area usually in km squared

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the 4 layers of the earth?

A
  1. inner core
  2. outer core
  3. mantle
  4. crust
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the 2 layers that the mantle is split into?

A
  1. asthenosphere- soft, plastic line rock in the upper mantle just below the lithosphere.
  2. lithosphere- solid top layer of crust in which plates are formed. consists of crust and upper mantle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how hot is it inside the core?

A

5000-7000 degrees celsius

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

through what process does earth generate its heat?

A

radioactive decay
- this involves the disintegration of uranium. when it decays heat is produced. much of the earth’s crust undergoes this. subatomic particles collide with each other and surrounding material inside the earth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the plate tectonic theory?

A

The lithosphere is broken up into ​large slabs of rock​ ​called ​tectonic plates​.

These plates ​move due to the ​convection currents ​in the asthenosphere, which push and pull the plates in different directions. Convection currents are caused when the less dense magma rises, cools, then sinks. ​ ​The edges of where plates meet are called​ ​plate boundaries​ ​(or plate margins).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how do convection currents work?

A
  1. earth’s mantle is hottest closer to the core, so the lower parts of the asthenosphere heat up , become less dense and slowly rise.
  2. as they move towards the top off the asthenosphere they cool down, become more dense and slowly sink.
  3. cooler magma is reheated and begins to rise again, creating a loop called a convection current.
  4. this causes drag to occur at the base of tectonic plates, causing them to move.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what are the 3 types of plate boundaries?

A
  1. constructive
  2. destructive
  3. conservative
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what occurs at a destructive margin where continental meets oceanic?

A
  1. denser oceanic plate subducts below the continental
  2. this leaves an ocean trench
  3. fold mountains occur due to sediment being pushed upwards during subduction.
  4. oceanic plate melts due to being heated by friction
  5. extra magma causes pressure to build up
  6. magma forces through weak areas
  7. Explosive, high pressure volcanoes erupt through the continental plate, known as ​composite volcanoes​.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what happens at a destructive margin where continental meets continental?

A
  1. Both plates are not as dense as oceanic so lots of ​pressure builds.
  2. Ancient oceanic crust is subducted
    slightly, but there is no subduction of
    continental crust.
  3. Pile up of continental crust on top of
    lithosphere due to pressure between
    plates.
  4. Fold mountains formed from piles of
    continental crust.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what happens at a destructive margin where oceanic and oceanic meet?

A
  1. the denser of the two oceanic plates will subduct below the other forming a deep sea trench and fold mountains will also occur
  2. Built up pressure causes ​underwater volcanoes bursting through oceanic plate.
  3. Lava cools and creates new land called island arcs​ (clusters of islands that sit in a curved line).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what happens at a constructive boundary where oceanic meets oceanic?

A
  1. Magma rises in between the ​gap left by the two plates separating​, forming new land when it cools.
  2. Less explosive underwater volcanoes formed as magma rises.
  3. 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).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what happens at a constructive boundary where continental meets continental?

A
  1. Any land in the middle of the separation is forced apart, causing a ​rift valley​.
  2. Eventually the gap will most likely fill with water and separate completely from the main island.
  3. The lifted areas of rocks are known as horsts​ whereas the valley itself is known as a ​graben​.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what happens at a conservative plate boundary?

A
  1. Between any crust, the ​parallel plates​ move in different directions ​or at ​different speeds​.
  2. No plates are destroyed so no landforms are created. When these plates move, a lot of pressure is built up. On oceanic crust, this movement can displace a lot of water.
  3. On continental crust, ​fault lines​ can occur where the ground is cracked by the movement.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

where are ocean trenches found and how do they form?

A
  • found along the seaward edge of destructive margins
  • formed due to subduction of the oceanic plate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

example of an ocean trench

A

Marianas trench, located on the western side of the Pacific Ocean.
- formed as the pacific plate descended below the smaller philippine plate
- max depth: 11km
- small slot shaped valley at its floor
- made up of the summits of 15 volcanoes- gham being its most well known of the islands.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

how do fault lines occur? example?

A

A fault is formed in the Earth’s crust as a brittle response to stress. Generally, the movement of the tectonic plates provides the stress, and rocks at the surface break in response to this.

  • san Andreas fault, located in western north america.
  • the faults trends north westward for 800 miles.
  • they run from the northern end of the gulf of California through western California. they pass seaward through the pacific in the vicinity of san fransico
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

when do ocean ridges occur? example?

A

where diverging plates are underwater an ocean ridge forms.

e.g. the midatlantic ridge is where the eurasian plate and the North American plate are moving apart.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

when do rift valleys occur? example?

A
  • where plates diverge beneath land, rising magma causes the continental crust to bulge and fracture, forming fault lines.
  • as the plates keep moving apart the crust between parallel vaults drop down to form a rift valley.

e.g. East African rift valley is a series of rift valleys that stretch from Mozambique to the Red Sea, about 4000km.
- it formed because the Somalian plates are diverging.
- volcanoes are found around rift valleys. i.e. mount Kenya and Mount Kilimanjaro (the 2 highest mountains in Africa) are volcanoes in the East African rift system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

hotspot

A

a hotspot is an area of intense volcanic activity away from plate margins, these are caused by magma plumes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

magma plumes

A

a magma plume is a vertical column of extra-hot magma rising from the mantle.
- volcanos form above magma plumes
- the plume remains stationary but over time the crust moves it
- volcanic activity in the part of the crust that was above the magma plume decreases as it moves away
- new volcanoes form in the part of the crust that is now above the magma plume
- as the crust continues to move, a chain of volcanoes is formed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Pangea

A

all of the earth’s landmass was one with no continents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

wegner’s 5 lines of evidence for continental drift

A
  1. jigsaw fit of continents
  2. geological fit- rock types
  3. tectonic fit- fragments of old fold mountains found on separated continents
  4. glacial deposits can be found in Antarctica, Australia, Africa, South America and India
  5. fossil evidence- some fossils found in between 2 continents only such as the mesosaurus which was found in South Africa and South America
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

ridge push

A

the process of material pushing out from the ridge (mid Atlantic ridge)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

slab pull

A

at subduction zones gravity pulls the oceanic plate down into the mantle. the crust is then melted and destroyed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

continental crust facts:
thickness
age
density
mineral content
rock type

A
  • 30-70km
  • over 1500 million years
  • 2.6g/m (lighter)
  • silicon, aluminium
  • granite
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

oceanic crust facts:
thickness
age
density
mineral content
rock type

A
  • 6-10km
  • less than 200 million years
  • 3.0g/m (denser)
  • silicon, magnesium
  • basalt
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

what type of lava occurs at constructive plate margins?

A

basaltic lava is formed here which is very hot and has low viscosity (very runny), so it flows easily and quickly.

eruptions with basaltic lava are frequent however not so dangerous as they are not so violent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

what type of lava occurs at destructive plate margins?

A

andesitic and rhyolitic lavas (more acidic lavas) are formed here- they are cooler and more vicious (thicker) than basilica lava so they don’t flow as easily.

these lavas usually flow intermittently (every once in a while) and the eruptions are short lived.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

characteristics of a shield volcano

A
  • gentle slopes
  • wide base
  • frequent eruptions of basaltic lava
  • lava flows at high speeds for long distances before cooling
  • usually non-violent eruptions
  • non-vicious lava due to basaltic composition
  • found at constructive boundaries
    Examples: Mauna Loa + Kilauea
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

characteristics of a composite volcano

A
  • steep sided with cone shape
  • high with narrow base
  • explosive eruptions f lava and ash
  • layers of alternating lava and ash
  • vicious lava builds in layers and does not flow far from the base
  • found at destructive boundaries
  • secondary or parasitic cones formed when the main vent gets blocked
    Examples: Mount St Helen, Etna and Montserrat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

VEI

A

the VEI is the scale used to measure the intensity of volcanic eruptions. It is measured on a scale of 0-8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

types of volcanoes from least to most dangerous

A
  1. Icelandic eruption- low viscosity and highly effusive. may hold water
  2. hawaiian- effusive, minor explosivity with fire fountain and low viscosity lava flow
  3. pelean- explosive eruptions with range of tephra with nuee ardent (glowing clouds) and pyroclastic flows
  4. Strombolian- eruption with gas bubbles so ejects tephra
  5. vulcanian- higher gas build up than Strombolian. highly vicious lava. series of short lived explosions with tephra including bombs
  6. pilinean- highly explosive, large eruption column (up to 45km), range of tephra and pyroclastic fallout including flows
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

what are the effects associated with volcanic eruptions?

A
  1. tephra
  2. volcanic gases
  3. pyroclastic flows
  4. lava flows
  5. mudflows (Lahars)
  6. acid rain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

what is tephra? what causes it?

A

tephra is rock fragments and particles ejected by a volcanic eruption.

they’re caused by high levels of silica in the magma, which causes gases to build up which leads to built up pressure. this is then released, throwing ash and fragments upwards into the air.

tephra can reach hundreds of thousands of km from the source

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

effects of tephra

A
  • when tephra is ejected it is electronically charged and causes lightning
  • disrupts communication lines
  • starts fires
  • poor visibility
    -respiratory issues
  • ash build up on roads can cause collapse
  • prevents aircrafts flying
  • destroys crops and kills livestock
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

what are volcanic gases? how do they form?

A

magma contains dissolved gases and when magma rises, pressure inside the magma is released and subsequently so does the gas.

  • if the gas is not released during the eruption they can escape through soil, volcanic vents and hydrological systems.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

what are the 5 types of volcanic gases?

A
  1. water vapour- most abundant gas in a volcanic eruption and it is harmless
  2. CO2- 180-440m tonnes released.
    - usually dissipates as its denser than air
    - high exposure leads to headaches, dizziness
  3. sulphur dioxide SO2- small amounts can irritate the respiratory system and eyes
    - causes acid rain
  4. hydrogen sulfide- in small amounts
    - highly toxic, colourless and very strong odor
    - causes unconsciousness and death
  5. hydrogen halide- when magma rises volcanoes emit the halogens in the form of hydrogen halides. e.g. fluorine, bromine, chlorine.
    - high solubility in water therefore can dissolve in water or plumes to form acid rain
    - ash can be coated in halides which can poison drinking water for livestock and people
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

what is a pyroclastic flow?

A

a pyroclastic flow is a dense, fast moving flow of solicited lava pieces, volcanic ash and hot gases. it is extremely dangerous to any living thing in its path.

  • travels at speeds of greater than 50mph.
  • rock ranging in size from small ash particles to boulders
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

what are lava flows?

A

lava flowing down the slopes of a volcano after it has erupted.
- speed and distance depends on the type of volcano and the viscosity
- most flows are generally slow so evacuation can take place

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

ash fallout

A

ash fallout is material that has been ejected from a volcano during an eruption and falls back onto the ground. when fallout consists mostly of ash its called ash fallout.
- sizes range from small particles to huge boulders

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

what are mudflows/ lahars?

A

mudflows occur when volcanic material mixes with large amounts of water e.g from rainfall or ice melt. this flows more quickly and can go for tens of kms.
- mudflows can bury or destroy natural habitats, settlements and infrastructure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

what is acid rain and how does it form?

A

volcanic gases can react with water vapour in the atmosphere, which then falls as acid rain- e.g. sulphur dioxide reacts with water to form weak sulphuric acid.

  • this can damage ecosystems and can also cause stone to deteriorate, damaging buildings, statues, etc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

how are volcanoes monitored?

A
  1. seismic activity
  2. gas emissions
  3. geological observations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

how are volcanoes monitored by seismic activity?

A

seismic activity always occurs before an earthquake/ eruption. it can be monitored using a seismograph and activity is measured on the Richter scale.

  • can also be detected by infra-sound (sub-audible sound below 20Hz)
  • IMS global infrasound network has over 60 stations around the world and detect volcanoes.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

how are volcanoes monitored by gas emissions?

A

as magma heats the surface of a volcano gases escape as pressure decreases. sulphur dioxide is the main component.

e.g. may 13th 1991 an increased amount of SO2 was released from Mt Pinatubo and 2 weeks later emissions had reached 5000 tonnes. 15th June it erupted.

60
Q

how are volcanoes monitored by geological observations?

A

there are several techniques:
1. slope angle- a tilt metre is used to measure changes in the slope angle.
-they are installed when the volcano is inactive to ensure no changes and the tilt angle is 0.
- slope angle changes due to more magma rising causing the volcano to expand.

  1. electronic distance measurements- used to measure horizontal movements. when the volcano expands before an eruption this distance will increase and change and can be recorded.
61
Q

methods to prevent volcanic eruptions

A

no prevention methods to stop the eruption from occurring however can prevent death and injury.

  • this is by not allowing building around volcanoes
62
Q

methods to mitigate the effects of a volcanic eruption

A
  • direct intervention e.g. building concrete walls to divert lava flows
  • strengthening buildings that are at risk of ash fallout or mudflow. e.g. implementing steel frames to give a sturdier structure
  • evacuation and exclusion zones
  • mitigating effects on health by having emergency rescue aid
62
Q

methods to prepare for volcanic eruptions

A
  • monitor volcanoes to increase the notice and therefore warnings can be issues early on
  • education for people living in volcanic areas
  • planned evacuation procedures
  • training response teams
63
Q

adaptation to volcanic eruptions

A
  • move away from the area at risk
  • capitalise on opportunities such as encouraging tourism
  • changes in profession could make you less susceptible to the impacts of eruptions
64
Q

methods of lava control

A
  1. bomb the volcano- Mauna Loa was bombed in 1935 to destroy lava tubes, robbing lava if an easy transport channel. This exposes the lava to air, cooling it down.
  2. cool with water- 1973 Elafell Icelandic volcano blasted with canons of sea water, the water turned into steam and the lava was dissipated.
    - 6.8billion litres were used. however this was easy as there is a large water supply and the lava was slow moving.
  3. build a barrier- 1983 Mt Etna
    - barriers of rock and ash were created in an attempt to divert the lava. 18m high, 10m wide and they were successful.
65
Q

CASE STUDY
eyjafjallajokull eruption:
- eruption date
- location
- VEI

A
  • 20th March- 23rd June 2010
  • located in Iceland on the constructive boundary where the North American plate is moving west and the eurasian plate is moving east. they are separating at 2.5cm/year
  • VEI= 3
66
Q

characteristics of eyjafjallajokull

A
  • volcano covered by an ice cap of 100km^2
  • composite volcano
  • 1651 metres tall and has a crater 3-4km in diameter
67
Q

causes of the eyjafjallajokull eruption

A
  • North American and eurasian plate are moving apart due to ridge push along the mid-atlantic ridge
  • magma fills the chamber below the volcano
  • several chambers combined produce significant volume of magma below the volcano
  • as the ice begins to melt glacial water begins filling the volcano where it met bubbling magma at the centre of the eruption
  • the rapid cooling caused the magma to shear into fine, jagged ash particles
68
Q

eyjafjallajokull primary effects

A
  • 250 million cubic meters of ash and tephra was emitted into the atmosphere
  • 20 farms were totally destroyed by a combination of flooding or ash
  • 30 000 tonnes of CO2 were released into the atmosphere each day
69
Q

eyjafjallajokull secondary effects

A
  • Airspace was closed leading to 95 000 cancelled flights during a 6 day closure period
  • £1.1 billion in losses from the airline industry alone
  • Currencies tied to tourist revenue (e.g. in Kenya and Turkey) fell due to the lack of visitors
  • Flooding due to melt of 150m thick ice cap destroyed part of Iceland’s route 1 road which goas around the coast of the country
  • The ash led to fluoride being put into local water supplies meaning farmers couldn’t allow their livestock to drink from it
70
Q

eyjafjallajokull short term responses

A
  • 700 people were evacuated in Iceland (500 of the famers). These people were cared for by 60 red cross volunteers
  • Dutch red cross set up 1500 beds in Schiphol airport for trapped passengers
  • declared state of emergency
  • people told to stay inside due to heavy ash fall in some areas
  • farmers told to keep livestock inside
  • roads closed for several days due to fear of flash flooding
71
Q

eyjafjallajokull long term responses

A
  • Significant research was triggered into the impact of volcanic ash on aircraft amongst calls from coms airlines that closure of airspace was unnecessary
  • Previous 27 national airspaces of the EU to be replaced with 9 functional airspace blocks (FABs). Hope to make controlling Europe’s airspaces simpler
  • Parts of route 1 were bulldozed to control the damage done
  • Roads and embankments were reconstructed within weeks
  • Compensation was given to travellers
72
Q

international cooporation

A

cooporation is one form of relationship between international bodies, often nation-states. this is often seen if one place suffers from a disaster.
- mutually agreed division of labour

73
Q

seismic hazard definition

A

the probable level of ground shaking associated with the recurrence of earthquakes

74
Q

focus point

A

The ​focus is the point underground where the earthquake originates from

75
Q

epicentre

A

The ​epicentre ​is the area above ground that is ​directly above​ the focus.

76
Q

Richter Scale

A

The Richter scale is the most common standard of measurement for earthquakes. It was invented in 1935. it has a scale of 0-10. it measures the ground deformation and energy release by an earthquake. each number is 3x larger than the last.

76
Q

magnitude

A

intensity of an earthquake, measured on the Richter scale

77
Q

The ​Modified Mercalli Intensity Scale (mercalli scale)

A

The Mercalli scale is ​subjective​, meaning sometimes it is disputed as it is dependent on human development being present rather than the strength of the seismic waves. used in the US.

78
Q

liquefaction

A

when the soil becomes saturated after mixing with groundwater during an earthquake. The vibrations of the earthquake cause this to act like a liquid and becomes very soft. often acts like quicksand.

79
Q

methods to predict earthquakes

A
  • by looking at past seismic events the probability of when an earthquake will occur may be possible. or looking at detecting pressure along fault lines.
  • remote sensing- the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance. studies changes in shape and size and groundwater levels.
  • radon gas emissions- an increase means that an earthquake is more likely to occur. also helps to understand where breakages in the fault are.
  • changes in animal behaviour as animals can smell gases- forces earlier evacuation. e.g. toads deserted their mating site 74km from epicentre of L’Aquila earthquake in Italy.
79
Q

landslides

A

ground shaking destabilises cliffs and causes landslides and rockfalls. heavy rain and unconsolidated and fractured rock are exacerbating factors.

80
Q

seismograph

A

used to measure an earthquake as it occurs. used to determine how much shaking has occurred.

81
Q

CASE STUDY
Nepal earthquake 2015:
- date and time
- location
- magnitude
- depth
- Nepal’s GDP Per capita

A
  • 25th April 2015, 11:26am
  • just outside of capital Kathmandu
  • 7.8 on the Richter scale
  • 15km (very shallow)
  • $882 per year (ranked 157th out of 185 for wealth).
82
Q

primary effects of Nepal 2015

A
  • 8632 people were killed immediately
  • 14 500 were left with injuries
  • 18 climbers were killed at Mt Everest base camp
  • 45 000 classrooms damaged
  • Landslides killed 2500 people
  • 600 000 homes destroyed
  • 50% of shops were lost leading to a loss of livelihood
  • 7000 schools destroyed
83
Q

secondary effects of nepal 2015

A
  • 2.8 million people were made homeless
  • Will take a decade to recover financially
  • 1.1 million children will be denied access to an education
  • Series of aftershocks damaged more buildings and slowed down the responses
  • Landslides damaged harvests leading to long term lack of food supplies
  • Tourism was reduced due to damage to heritage sites and closing of Everest
  • Following year 72% reduction in tourists
  • $6.6 billion as the total cost of rebuilding
84
Q

short term responses of Nepal 2015

A
  • People dug with their bare hands to try and find loved ones
  • Funeral piers set up in the street to dispose of the dead
  • Rescue teams with equipment sent from USA, UK, Pakistan, Germany and India
  • Disaster emergency committee (DEC) launched appeal and 310 000 people were helped. UK public donated £41 million
  • 15,000 temporary learning centres installed
  • Oxfam also provided clean water to over 400,000 people
  • Islamic relief provided 2500 meals to families
  • Oxfam installed a 11,000L water tank and provided a total of 58,000L of water
85
Q

long term responses of Nepal 2015

A
  • Asian development bank gave $200 million to help the rebuilding process
  • Medical teams remain active and are educating people in how to respond in future
  • New national building codes have been created and are starting to be enforced
  • Facebook designed a safety check for future disasters to enable people to tell loved ones they are ok
  • Nepalese soldiers and UK engineers assessed the damaged areas and worked to ensure all buildings that were still standing were safe
  • Oxfam ran a cash for work programme, helping 15,000 people to earn as they rebuilt their homes
86
Q

causes of the Nepal earthquake 2015

A

Release of pressure at the Indian/Eurasian destructive plate boundary where both plates are continental

87
Q

why was Nepal so at risk?

A
  • on a plate boundary
  • LIC
88
Q

tropical storm definition

A

a tropical storm is a violent rotating storm which occurs in the mid- latitudes i.e the tropics

89
Q

conditions for topical storms to form

A
  • must be within the latitude lines 0-60°.
  • begin near to the equator and move outwards
  • have to be formed in seas with temperatures over 27°
  • low wind shear (a change in wind speed and/or direction over a short distance).
90
Q

when do tropical storms begin to dissipate and why?

A

when they hit land because the energy is dispersed

91
Q

steps to the formation of a tropical storm

A
  1. warm air rises from the ocean and as it rises it leaves a space below it called an area of LOW PRESSURE. this space is instantly filled by surrounding air rushing in causing strong winds
  2. the air that rushed in now warms up and rises too. this rising air brings moisture which cools and condenses to form towering storm clouds. this forms the eye wall.
  3. when the cooled air descends it will form an area in the centre called the eye
  4. due to the wide near the equator the tropical storm starts to move from east to west. the spin of the earth causes these winds to curve and leads to the storm starting to spin.
92
Q

why do tropical storms spin?

A

due to the Coriolis effect. the Coriolis effect deflects objects within a rotating system. occurs due to the earth’s rotation.

  • in the northern hemisphere storms deflect clockwise (to the right).
  • in the southern hemisphere objects deflect to the left to move anti clockwise. still look to move right however.
93
Q

what are the peak times for tropical storms?

A

august- October. however they form in the northern hemisphere from June-november and southern hemisphere from November-april. the majority of storms do not reach land. however high magnitude storms are thought to be increasing in frequency.

94
Q

methods to monitor tropical storms

A
  1. aircrafts and drones fly into storms and monitor windspeed and barometric pressure.
  2. satellites peer through clouds to scan rainfall inside the hurricane, providing 3D views. the data feeds into weather models that run on super computers and scientists are always looking for new tweaks that will improve storm forecast.
95
Q

how are tropical storms measured?

A

on the saffir simpson scale from a scale of 1-5. 5 being the most destructive.

96
Q

hazards associated with tropical storms

A
  • storm surges
  • landslides
  • river flooding/ heavy rainfall
  • high windspeeds
97
Q

what is s storm surge? how high are they generally?

A

A storm surge is an influx of sea or lake water pushed ashore by the strong winds in a storm.
- generally 1-2 feet tall.

98
Q

what can make storm surges worse?

A
  • bays, concave or high angled coastlines
  • high tide
  • elevation of the land/ height
99
Q

what is a landslide?

A

the mass movement of a mass of rock, debris of earth moving down a slope.

100
Q

where are landslides most common?

A
  • areas where wildfires often occur so there is little vegetation
  • areas where landslides have occurred before
  • steep slopes, areas at the bottom of canyons
101
Q

what can exacerbate impacts of landslides?

A
  • snow melt
  • heavy rainfall
  • repeated freezing and thawing
  • human modification
102
Q

what is river flooding? where is the most at risk?

A

when the level in a river rises above the banks and overflows onto land either side.
- floodplains
- houses on a confluence

103
Q

how do strong winds occur? which areas are at the highest risk?

A

warm moist air is drawn up from the ocean leading to strong winds.
- eye wall or in the direct path.

104
Q

CASE STUDY
hurricane sandy (HIC):
- date
- location
- category
- max windspeeds

A
  • 22nd October- 2nd November 2012
  • stroke New York and New Jersey 29th however also affected Kingston, Jamaica 22nd as a low pressure system.
  • category 3
  • max windspeeds of 75mph
105
Q

why did sandy turn back into land to hit New York and New Jersey?

A

cold air to the north and high pressure over Greenland which prevented the storm from moving across the Atlantic. also was a jet stream to the west, which combined pushed the storm into warmer coastal waters. the timing was also hazardous as there was a full moon meaning tides were already high.

106
Q

primary effects of hurricane sandy

A
  • Worst rainfall in a century brought widespread flooding
  • 111 people were killed
  • Boardwalk in Atlantic city tourist destination was destroyed
  • 1.8 million in New Jersey and New York were without electricity
  • 600 000 homes were either damaged or destroyed
  • $60 billion in damage was done
  • One crane collapsed
  • Part of the subway was flooded
107
Q

secondary effects of hurricane sandy

A
  • $18 billion in financial losses from closure of New York businesses
  • Flooding hampered firefighting and 80 homes were lost due to gas fires where firefighters could not reach the area
  • Fuel shortages led to long queues at petrol stations
  • All 3 of New York’s airports were immediately closed. Leaving thousands stranded in New York and all over the world
  • Commuters couldn’t get to work due to closed subway and railway lines due to flooding. Reducing productivity.
  • New York marathon had to be cancelled (loss of tourism revenue)
  • Stock exchange closed for 2 days for the first time since 9/11
  • East coast oil refinery was destroyed restricting USA oil production
  • Both Barack Obama and Mitt Romney had to stop election campaigns for 3 days because of the disaster
  • Lack of power followed by snow and cold weather led to people freezing and a rise in crime in unoccupied buildings
108
Q

short term responses to hurricane sandy

A
  • The red cross sheltered 11 000 people
  • President Obama declared a state of emergency in New York and New Jersey. Freeing up more money and resources to help with the relief effort
  • Marathon runners helped to fundraise by doing an unofficial run around the city
  • Empty hotels and apartments were used to shelter some of the homeless
  • Red cross deployed 17 million meals and snacks (though was criticised for focussing on publicity)
  • Red cross also donated 7 million relief items which included cold weather clothing due to the arrival of a snow storm
  • Americare (NGO) supplied $3.5 million in medical supplies to the affected areas
  • FEMA deployed disaster managers and liaison experts to areas likely to be impacted before then event so they were already in place
109
Q

long term responses to sandy

A
  • Long term planning put in place for how to deal with future events. Especially because of the rising threat posed by climate change
  • In 2013 a law passed allowing $50 billion of federal money to be spent on repairing the damage done by Sandy
  • Even today most of this money has not been spent
  • Investigations carried out into a micro-grid system for New York’s electricity supply to avoid widespread blackout following disasters
  • Rental assistance fund for those survivors who have lost their uninsured home and cannot afford to leave emergency accommodation
  • New, stricter building codes enforced for coastal properties and an alteration to the way electricity is supplied across the region
110
Q

CASE STUDY
Typhoon Haiyan 2013
- date and time
- location
- track
- category
- max wind speeds
- GDP per capita
- % of population in poverty

A
  • 8th November 2013, 4:40am local time made landfall
  • the Philippines, tacloban and ormoc were cities that were hit the hardest and Vietnam
  • super typhoon category 5, 4th most intense storm ever recorded
  • 196mph
  • tracked north west
  • $4700 GDP per capita
  • 27% live in poverty (less than $2 per day)
111
Q

primary effects of Haiyan

A
  • Roughly 6500 people killed. Many were drowned by the storm surge.
  • 90% of the city of Tacloban was destroyed. Over 600,000 people displaced and 40,000 homes wrecked.
  • Tacloban airport terminal severely damaged.
  • 30,000 fishing boats destroyed.
  • Power lines brought down by the winds.
  • Crops destroyed.
  • Widespread flooding as a result of the 400mm of rain which fell.
112
Q

secondary effects of Haiyan

A
  • 14 million people were affected.
  • 6 million people lost their source of income.
  • Flooding caused landslides and roads were blocked, which cut off aid to isolated communities.
  • Some areas had no electricity for over a month.
  • Ferry services and flights were disrupted within the Philippines, which meant aid could not reach those who needed it.
  • Shortages of fresh water, food and shelter affected many people causing the outbreak of disease.
  • Many jobs were lost, hospitals were damaged, shops and schools were destroyed affecting people’s livelihood and education.
  • Looting and violence broke out in Tacloban.
113
Q

short term responses of Haiyan

A
  • US aircraft carrier George Washington and its helicopters conducted a search and rescue mission and delivered aid.
  • 1200 evacuation centres were set up for the homeless.
  • The French, Belgian and Israeli governments set up field hospitals to help the injured.
  • $23 million in immediate response relief. $3m from Asia pacific disaster fund, $20m from the japan fund for poverty reduction
  • 150 foreign medical teams coordinated
  • 582 public healthcare facilities assessed and mapped
  • 108,783 children vaccinated against measles
  • over 500 tonnes of medical equipment sent
  • 500,000 received emergency shelter materials
114
Q

long term responses of Haiyan

A
  • “Cash for work” programmes were set up. People were paid to help clear debris and rebuild Tacloban.
  • Aid agencies (e.g.Oxfam) supported the replacement of fishing boats – a vital source of income.
  • Cyclone shelters have been built in coastal areas.
  • Thousands of new homes have been built away from areas at risk of coastal flooding.
  • The rebuilding of roads, bridges, airport facilities, schools, and homes.
  • 44,000 families given seeds to plant their own food
  • 80,000 given fertiliser. this will feed 100,000 per year
  • 97,000 screened for malnutrition
  • 420,000 provided with educational materials
  • 55,000 received tools to rebuild homes
  • 50,000 received solar lanterns
  • 140,000 temporary learning sites for children
115
Q

what is a wildfire?

A

a wildfire is any rural fire which is uncontrolled and spreading

116
Q

what 3 things does a wildfire need to form

A
  1. a heat source e.g. the sun, bbq, cigarettes
  2. a fuel to burn e.g. dry grass, leaf litter and vegetation
  3. an oxygen supply
117
Q

in which years do more wildfires/ more intense wildfires occur

A

El Niño years (every 6-8 years) or Indian Ocean dipole years

118
Q

what is the El Niño effect?

A

el nino is a climate cycle in the Pacific Ocean with a global impact on weather patterns. the cycle begins when warm water in the western tropical Pacific Ocean shifts eastward along the equator towards the coast of South America.

  • normally, this warm water pools near Indonesia and the Philippines. this is capable of leading to dryer and hotter weather conditions.
119
Q

when is the El Niño effect declared?

A

An El Niño is declared when sea temperatures in the tropical eastern Pacific rise 0.5 °C above the long-term average.

120
Q

what 3 things affect wildfire behaviour?

A
  1. weather- e.g. sun dries out plants, wind provides oxygen
  2. topography e.g. steeper slopes mean fires can travel quicker downhill but slower uphill
  3. fuel- highly flammable materials cause faster burning fires however fuel can be removed such as leaf litter
121
Q

how is fire able to transfer from one object to the other without touching it?

A

due to radiation- allows the transfer of fire to an adjacent object by causing it to combust without touching it.

122
Q

how can wildfires be managed/ mitigated?

A

mitigation:
- controlled burning- reduces the amount of flammable material bur has to be strictly monitored
- smokey bear method- trim tree limbs 10ft above the ground to prevent ladder fuels
- install 1/8 inch metal mesh screens over vents and under desk to prevent ember intrusion
- clean gutters
- water grass
- enclose homes

managing the effects:
- evacuation plans
- warnings broadcasted
- wildfire maps
- personal emergency plans
- emergency supplies

123
Q

CASE STUDY
Australia wildfires 2019-2020

  • main locations
  • causes
A

causes:
- positive indian ocean dipole, meant wetter west and drier east
- lightning storms (91,000 at Christmas)

locations:
- Sydney
- Victoria- 1.2m hectares burnt here
- new south Wales
- cobargo

124
Q

primary effects of the Australia wildfires

A
  • 100,000 cows and sheep killed
  • 33 deaths
  • 2500 homes destroyed
  • more people seeking medial help for asthma
  • 18m hectares burnt
  • $100billion in damages
  • 21% of forest affected
125
Q

secondary effects of the Australia wildfires

A
  • long term damage to ecosystems
  • long term lung issues from pollution
  • poor air quality, smoke reached Chile and argentina
  • mental health impacts long term
  • agricultural decline long term
126
Q

primary responses to the Australia wildfires

A
  • government initially invested $150m in rebuilding
  • 2000 firefighters New South Wales
  • 1000s of volunteers paid by the Red Cross
  • australias military involved in the rescue of people from homes
  • foregin aid offered by NZ, US, Canada
  • fire fighters being sent by New Zealand, Canada
127
Q

secondary responses to the Australia wildfires

A
  • $200 million government invested later to help native wildfire
  • 100 aircrafts dropped water
  • rebuilding of homes took place
  • reviews of buildings in bush fire zones
  • calls for a paid fire service
128
Q

MULTI HAZARDOUS CASE STUDY: Philippines

background? why is the Philippines considered a multi- hazardous area?

A
  • The Philippines is a group of 7000 islands in the South China Sea in Southeast Asia. It has a vulnerable population of 98 million people who are at risk from a variety of hazards, including 11million people in the densely populated coastally situated megacity of Manila, the capital
  • the Philippines sits on a plate boundary where the eurasian plate and Philippine plate meet.
  • the plate boundary is destructive
129
Q

potential hazards occurring in the Philippines

A
  1. volcanic eruptions- mount pinatubo 1991killed 500.
  2. tropical storms- typhoon Haiyan 2013 killed 7000
  3. earthquakes- 1999 Luzon island earthquake measured 7.8 and killed over 1500 people
  4. tsunamis -Tsunami that hit Mindanao in 1976 was 4-5m high and damaged 14 buildings
  5. heavy rain
  6. flooding
130
Q

why is being a multi hazardous area a struggle for the filipino government?

A
  • a lot of different hazards and not a lot of money, opportunity costs
  • could use too much for one whilst another one could occur.
131
Q

why does the Philippines need so many responses?

A
  • one of the most disaster prone countries in the world
  • 268 recorded disasters inn 3 decades
  • ranks 8th according to the world bank’s natural disaster hotspot list
  • 239 disasters 1990-2009
  • 30% of disasters occurring in Asia have been in the Philippines. this has affected 36.5 million people in total
132
Q

the Philippines have a natural disaster coordinating council. why is this necessary?

A
  • 18 different agencies come together to communicate ideas.
  • it is an inter agency council for preparation and prevention, mitigation and response
133
Q

why is it important that the local government plays a significant role?

A
  • to recover faster as they will know the area the best.
  • identify risks early on
  • use their knowledge to build a resilient culture
  • trusted by people
  • messages can be sent out quickly
  • effective response on all levels
134
Q

what has been done in terms of early warning systems?

A
  • PHIVOLCS + PAGSA are expanding facilities and equipment and training of personnel to enhance monitoring and forecasting.
  • new doppler radars
  • NDCC undertaking a multi hazard mapping and assessment project. data from past events is used.
135
Q

what has Philippines done in terms of management?

A
  • Established in 2009, the National Disaster Risk Reduction and Management Council is a working group of government, non-government, civil society, and private sector organizations. The Council is responsible for ensuring the protection and welfare of the people during disasters.
  • Management Act of 2010 was a landmark legislation that shifted the Government of the Philippines’ focus from emergency relief to disaster risk reduction and prevention.
136
Q

LOCAL SCALE HAZARD RESPONSE CASE STUDY: Caracas

  • where is Caracas?
  • background
  • GDP per capita
A

Caracas is the capital city of Venezuela. Caracas is primarily situated in the base and on the flanks of a large valley making it very susceptible to landslides triggered by tropical storms of tectonic activity.
- worlds 70th most wealthy nation
- GDP per capita= $17,000

137
Q

which boundary is Caracas situated on?

A

Situated on boundary of Caribbean and South American plates with faults running through the city and under the main airport.
- caracas is also situated on the equator, making it very hot.

138
Q

what hazards is Caracas exposed to and what are the characteristics of Caracas?

A
  • landslides particularly because it is situated on a valley floor
  • liquefaction during earthquakes which have occurred 3 times in the last 400 years. The last major earthquake was in 1967 (mag 6.5) and killed over 300 people.
  • cyclones
  • Slope angles regularly exceed 80% making landslides and runoff major hazards in the Caracas basin
139
Q

Social characteristics reflecting hazard impacts

A
  • sharp social divisions, reflected in the occupancy of residents in different areas. upper class valley floor, lower class in shanty towns on hillsides.
  • upper class gained wealth through commerce and urban real estate. occupy the eastern margins of the valley. their homes are built to international standards making them likely to withstand earthquakes. far from the valley sides to avoid landslides.
  • middle class gained wealth through petroleum wealth. occupy the city centre plus residential suburbs. houses are smaller and less well constructed however modern materials are used.
  • social lower class are labourers and servants. occupy hillsides in barrios. have adopted a fatalistic view. rewards in the city are worth more.
  • The water supply for Caracas shows no consideration of hazards or impacts. All 3 supply lines cross major faults which could be lost in a disaster
140
Q

economic characteristics of Caracas

A
  • Venezuelan economy based on 50% of oil sales
  • caracas is focused on banking services, shops. being service focused means that this does little help for improving hazard response.
  • Economic divisions of late have led to rallies on both sides of the wealth divide asking for greater equality.
  • The economy of Caracas would be badly hit by any future disaster as recent rapid growth means there are more people than the city can comfortably accommodate/employ.
141
Q

political characteristics of Caracas

A
  • high crime rates
  • dictatorship
142
Q

hazard response in Caracas

A
  • people seek shelter in multi-storey structures
  • risk zoning
  • orienting streets parallel to the flow downslope direction to act as an overflow channel
  • The government funds research bodies such as the Venezuelan foundation for seismological research, which conduct research and experiments to assess the risks of different parts of the city.

physical geography (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions