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Physical Geography A Level 🌋🌊🔥 > Natural Hazards 🔥🌊🌋🌲 > Flashcards

Natural Hazards 🔥🌊🌋🌲 Flashcards

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1
Q

What are the different types of hazards?

A

. Earthquakes
. Tropical storms
. Volcanoes
. Tsunamis
. Landslides
. Flooding
. Heatwaves
. Heavy snow

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2
Q

What is hazard risk?

A

The probability or chance that a natural hazard may take place

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3
Q

What is hazard perception?

A

.The way we process and filter the information we receive for hazards
. Warnings or risk involve people going through stages which shape their perspectives and behaviour

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4
Q

What are the factors influencing hazard perception?

A
  1. Cultural factors ➡️ indigenous settlers not exposed to warnings, certain people more exposed to war msg as happened for hundreds of years
  2. Economic factors ➡️ certain people more educated in rich countries, people can have better infrastructure and warning systems if wealthy
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5
Q

What is fatalism hazard response?

A

. May have lived through events or hazards many times
. As they’re ‘normal’ people don’t fear the, and do nothing about it
. Often consider cons are smaller than pros

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6
Q

What is mitigation hazard response?

A

. Actions taken to reduce or eliminate threat of human life or property
. Can include adaption+ preparation+ how individuals can reduce impact of hazard
. Methods need to go through cost- benefit analysis

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7
Q

What is risk sharing hazard response?

A

. Spreading risk reduces any one group/ individuals risk
. May involve spreading financial burden of hazards+ adaptation strategies in future too?

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8
Q

What is adaptation/ adjustment hazard response?

A

. Start to change way of living due to natural hazard
. E.g building structures, research can mainly impact people’s life’s
. Christchurch 2010 earthquake government analysed buildings and built structures on them

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9
Q

What is the prediction hazard response?

A

. Knowing where and when hazards may occur can be useful and lead to less deaths
. Seismic monitoring of areas around earthquake, animal behaviour, weather systems commonly used as strategies
. Only worthwhile if information is acted on not ignored

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10
Q

What is the management hazard response?

A

. Manage ourselves + property to minimise damage
. Depends on wealth of county e.g Japan uses tsunami warning system and Philippines relies on basic weather reports
. Management can’t be done for all natural hazards like volcanic ash falls, wildfires

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11
Q

What does the park model show?

A
  1. Immediate responses after hazard has occurred ➡️ rescue teams, charity help
  2. Rehabilitation ➡️ efforts made to restore and community structures at least temporarily
  3. Reconstruction ➡️ permanent changes introduced to restore quality of life
    . Larger the dip the worse economy is effected
    . Also called disaster response model
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12
Q

What are some factors influence the park mode?

A
  1. Economic development ➡️ lack of building infrastructure, prevention methods
  2. Education ➡️ more people educated better the response
  3. State of the country ➡️ LIC’s more likely to receive help from countries
    . HIC’s have people who can help internally
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13
Q

What does the Hazard management cycle say?

A
  1. Hazard event + Risk ➡️ hazard severity probability
  2. Response ➡️ rescue and evacuation+ relief + external support
  3. Recovery ➡️ long term recovery:internal and reconstruction process
  4. Prevention / mitigation ➡️ ongoing process to lessen severity of hazard on people / property
  5. Preparation ➡️ actions prior to event to activate necessary resources
    . Cyclical movement as no natural hazard is guaranteed once
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14
Q

What is the lithosphere?

A

The solid top layer of crust in which plates are formed consists of crust and upper mantle

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15
Q

What is the asthenosphere?

A

Soft, plastic like rock in the upper mantle just below the lithosphere

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16
Q

What is the process by which earth makes heat?

A

Radioactive decay

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17
Q

What is thought to have formed earth?

A

. Earth arisen from cloud of gas and dust in space
. Solid particles called ‘planetesimals’ condensed out of cloud

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18
Q

What is happening to earth now?

A

Earth is cooling now but very slowly and it is close to a steady temperature

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19
Q

What are the waves called that travel from an earthquake?

A

Seismic waves

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20
Q

How does radioactive decay work?

A

. Produces subatomic particles that zip away
. These later collide with surrounding material inside earth

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21
Q

What’s earth’s core temperature estimated to be?

A

Around 5,000-7,000 degrees Celsius

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22
Q

How long did Wagener think the plate movement has taken since Pangea formed?

A

300 million years

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23
Q

What was found when the mid-oceans were mapped?

A

. Mid ocean ridges ➡️ new ocean floor being created

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24
Q

What did Wagener initially struggle to explain?

A

Physically how the plates could move

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25
Q

As well as climate and landscape what else proved the theory?

A

Fossils on different continents and how the plates all fit into each other

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26
Q

When it refers to the crust being in pieces what are these ‘pieces’?

A

The continent pieces of the earth ➡️ tectonic plates

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27
Q

Explain convection currents

A
  1. Heat source (radioactive decay) in earth’s core causes rock to rise
  2. Semi molten rock then gets pulled apart due to direction of convection currents
  3. This rock then cooled and sinks down to be reheated
    . The process then repeats itself
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28
Q

What is the jigsaw fit for plate tectonics?

A

The coastlines of continents all fit together - explained by:
. Coastal erosion + coastal deposition + rises in sea levels + changes in land = all due to continental separation

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29
Q

What is the Geological fit in terms of plate tectonics?

A

. Geology of South America snd West Africa mapped revealed ancient rock outcrops over 2,000 million years old were continuous from one continent to next
. Geological fit of opposing continental coastlines

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30
Q

What is the tectonic fit in terms of plate tectonics?

A

. Fragments of fold mountains from 450-400 million years ago found on many continents
. When re-assembled they all fit together to form a linear feature
. Caledonian/ Acadian mountain belts at the end of Caledonian

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31
Q

What are glacial deposits in terms of plate tectonics?

A

. Glacial deposits found in many different continents
. If plate hadn’t moved the ice sheet would extend from South Pole to equator at time which was very unlikely
. Stretches made on bedrock made by blocks of rock embedded in ice as glacier move show direction of glacier
. Permo- Carboniferous glaciation as evidence

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32
Q

What is fossil evidence in terms of plate tectonics?

A

. If continental drift not occurred alternative explanations would be:
1. Species evolved independently on separate continents ➡️ Darwin’s theory
2. Swam to other countries to establish second population ➡️ physiologically impossible to swim ➡️ must have been joined
. When continents of southern hemisphere re-assembled fossils show linear and continuous patterns of distr

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33
Q

What is the idea of paleomagnetism?

A
  1. Oldest material found on sides of ocean ridge
  2. Newest material found in centre of ridge
    . New material constantly produced at the mid- oven ridge+ takes magnetism of Earth at time as Earth’s magnetism randomly flips
    . Now and again can see a striped pattern in magnetism and match it to age + possible due to sea floor spreading process
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34
Q

What is ridge push?

A

The process of material pushing out from the ridge

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35
Q

What are subduction zones?

A

Gravity ‘pulls’ the ocean plate down into the mantle. This destroys crust material and keeps earth in shape

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36
Q

What is slab pull?

A

Pull on a plate being subducted

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37
Q

What are some features of continental crusts?

A

.Thickness = 30-70 km
. Age = over 1,500 million years old
. Density = 2.6 g/m (lighter)
. Mineral content = Mainly silicon, oxygen, aluminium
. Rock type = Granite

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38
Q

What are some features of oceanic crusts?

A

. Thickness = 6-10km
. Age = less than 200 million years old
. Density = 3.0g/m (denser)
. Mineral content = mainly silicon, magnesium, oxygen
. Rock type = basalt

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39
Q

What is an example of a destructive plate margin?

A

Indo- Australian+ pacific plate

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40
Q

What is an a example of a constructive plate margin?

A

North American plate and Cocos plate

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41
Q

What happens at constructive plate margins?

A

Plates move apart from each other

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42
Q

What are some tectonic features at constructive plate margins?

A

. Rift valleys
. Ocean trenches
. Made ocean ridges
. Volcanoes

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43
Q

What are some examples of tectonic features at constructive plate margins?

A

. African rift valley
. Mid Atlantic ridge

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44
Q

What happens at destructive subduction plate margins

A

Denser oceanic plate subducts below the light continental crust

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45
Q

What tectonic features form at oceanic oceanic destructive plate margins?

A

. Submarine volcanoes
. Earthquakes
. Ocean ridges
. Island arcs

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46
Q

What tectonic features form at oceanic continental destructive plate margins ?

A

. Earthquakes
. Volcanoes
. Young fold mountains
. Ocean trenches

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47
Q

What are some examples of oceanic oceanic destructive plate margins?

A

. Mariana Trench
. Japan pacific plate

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48
Q

What are some examples of oceanic continental destructive plate margins?

A

. Chile and Peru trench on the Nazca plate
. Atacama trench

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49
Q

What happens in collision plate boundaries?

A

2 continental plates move together

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50
Q

What forms at collision plate boundaries?

A

. Young fold mountains
. Powerful earthquakes

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51
Q

What is an example of collision plate boundaries?

A

The Himalayans

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52
Q

What happens at conservative plate boundaries?

A

2 plates collide and slide past each other causing friction

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53
Q

What are some tectonic features at conservative plate margins?

A

. Earthquakes
. Fault lines
. Tsunamis
. Ocean ridges

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54
Q

What is an example of a conservative plate margin?

A

. San Andreas fault line in California

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55
Q

How are mid Atlantic ridges formed?

A
  1. Separation of plates moving away causes convection currents to push magma to surface
  2. Lava them cools to form basaltic material
  3. Newer material pushes older material to the sides (ridge push)
  4. Seen through magnetism of material due to changes in earth’s magnetic field
  5. Over time this forms mid Atlantic ridges
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56
Q

How are rift valleys formed?

A
  1. Warping of crust takes place as magma rises as plates driven apart
  2. Tensional faults + cracks appear allowing out gassing and steam eruptions
  3. Plates continue to move apart due to convection currents
  4. Blocks of crust descend into mantle forming valleys
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57
Q

How are horsts and grabens formed?

A

Conventional currents in asthenosphere cause extensions of crust. As crust extends garbens (down dropped blocks) and horses (up thrown blocks)are formed

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58
Q

What are at conservative plate margins?

A

Though almost invisible large fault line around conservative margins can be visible ➡️ San Andreas fault in California

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59
Q

Why may conservative plate margins be considered the most deadly?

A

. Although frequency relatively low when occur magnitude on Richter scale incredibly high
. Aftershock cause additional stress and have focus closer to earth’s crust ➡️ higher magnitude

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60
Q

What can be used to predict earthquakes?

A

Seismic monitoring uses sensitive seismographs to record ground motion from seismic waves created by earthquake

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61
Q

What are the 3 types of destructive/ convergent plate margins?

A
  1. Oceanic plate moves towards continental plate
  2. Oceanic plate moves towards oceanic plate
  3. Continental plate moves towards continental plate
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62
Q

What are the location of earthquakes and volcanoes on a world map?

A

. Both earthquakes and volcanoes found on plate boundaries of continents
. E.g ring of fire many volcanoes and earthquakes on it as where pacific and Philippines plate meet for example
. Anomaly could be in middle of Pacific Ocean seeing hazards there

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63
Q

What are hotspots?

A

. In areas such as Hawaii mantle plumes (areas of rising hot magma) cause melting of material in lithosphere due to tiny cracks in the crust which rises through fissures and causes volcanoes

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64
Q

What are some features of a composite volcano?

A

. High with narrow base
. Layers of alternating ash and lava
. Viscous lava builds in layers + does not flow far from crater
. Found at destructive plate margins
. Steep sided with distinctive cone shape
. Secondary or parasitic cones formed when main vent blocked
. Explosive eruptions of lava and ash
. E.g Montserrat , Etna and Mt St Helens

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65
Q

What are some features of a shield volcano?

A

. Frequency eruptions of basic lava
. Lava flows at high speeds and for long distances before cooling
. Non- viscous lava due to basaltic composition
. Found at constructive boundaries
. Usually non violent eruptions
. Gentle slopes and a wide base
. E.g Mauna Loa and Kilauea

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66
Q

What does viscosity mean?

A

Viscosity of liquid a measure of its resistance to flow thus low resistance = runny liquid state and Hugh resistance = thick sticky half liquid state

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67
Q

What affects magma viscosity?

A

Silica content in the magma

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68
Q

What are the 6 types of eruptions?

A
  1. Icelandic
  2. Hawaiian
  3. Strombolian
  4. Plinian
  5. Vulcanian
  6. Pelean
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69
Q

Describe pelean eruptions

A

. Explosive eruptions
. Range of tephra
. Nuee ardent (glowing clouds)
. Pyroclastic flows

70
Q

Describe Hawaiian eruptions

A

. Effusive
. Minor explosively with fire fountain
. Low viscosity lava

71
Q

Describe Strombolian eruptions

A

. Gas bubbles
. Eject tephra (ash and lapilli)

72
Q

Describe Vulcanian eruptions

A

. Higher gas build up than Strombolian
. Highly viscous lava
. Series of short lived explosions with tephra including bombs

73
Q

Describe Icelandic eruptions

A

. Low viscosity
. Highly effusive
. May have water therefore phreatic

74
Q

Describe plinian eruptions

A

. Highly explosive
. Large eruption column (up to 45km)
. Range of tephra
. Pyroclastic fallout including flows

75
Q

What is used to measure the explosively of a volcano?

A

The volcanic explosivity index
. Goes from 0-8

76
Q

What are primary effects?

A

Effects that occur immediately along with the event

77
Q

What are secondary effects?

A

Direct consequences of the event but not immediate

78
Q

Is there a high chance of you being killed by an earthquake?

A

No it’s fairly small

79
Q

What makes volcanoes deadly?

A

Other hazards associated with it can be deadly and lead to huge amount of deaths + injuries

80
Q

Give a brief summary about lahars

A

. Lahars = mix of cold water+ rock fragments ➡️ flow down steep side of volcano
. Form when erupted volcanic material gets saturated during periods of heavy rain
. Don’t have to be immediate after volcano
. Can pick up material as move ➡️ most common at stratovolcanoes + can destroy anything
. Capable of setting like concrete ➡️ hard to remove

81
Q

Give a brief summary of mudflows

A

. Saturated soil filled with water flows down slope
. From when torrential+ heavy rain absorbed by soil or material
. Rush down slopes up to 60 miles per hour
. Can cause great damage to life + property ➡️ boulders as large as houses have been removed by mudflows
. Found at base of volcano

82
Q

Give a brief summary of tephra

A

. Any material that is ejected by a volcano in the air
. Formed of typically glassy particles from cooling drops of magma
. Can stay in clouds above volcano for weeks forming ‘volcanic winters’ sometimes
. When cooled can solidify to form rock
. Sediment can build up + form fossils

83
Q

Give a brief summary of nuées Ardentes

A

. Fast flowing, turbulent cloud of hot gas+ ash erupted from volcano ➡️ Pyroclastic flows
. Formed during explosive eruptions as columns of erupted material collapse
. Neatly impossible to escape them + can destroy anything in path
. Cause severe burns+ inhaling of toxic gases

84
Q

Give a brief summary of lava flows

A

. Streams of molten rock that pour or ooze from erupting vent in volcano
. Formed when volcano erupts and pressure is released causing magma to rise
. Destroys anything in path
. Makes water acidity rise + warmer + form new land on oceanic islands

85
Q

Give a brief summary of volcanic gases

A

. Gases erupted by a volcano including co2, hydrogen, fluoride, sulphur dioxide, hydrogen sulphide
. Formed cause magma contains dissolved gases in it + when erupted gases are released
. Can cause cattle + people to die in high amounts
. Can lead to crop failure and deformity too

86
Q

Give a brief summary of acid rain

A

. From of precipitation with acidic components e.g sulphuric or nitric acid
. Formed by release of sulphur dioxide+ nitrogen oxides in atmosphere
. Can cause trees + plants to wolf or die due to acidity of rain
. Can erode surfaces like limestone+ kill wildlife in water

87
Q

Give a brief summary of ash fallout

A

. Another generic term for ash and tephra that falls to earth’s surface from eruption cloud
. Explosive eruptions cause gases to be released forming ash clouds + tephra
. Can cause eye + upper airway irritation
. Can cause major to minor damage on vehicles and buildings as well as vegetation

88
Q

Give a brief summary of Pyroclastic flows

A

. Hot typically 7800 degrees Celsius chaotic mixture of rock fragments, gas and ash ➡️ travels rapidly down sides of volcano
. Formed when volcano erupts and metrical falls to ground
. Extremely destructive due to high temperature + mobility
. Hard to escape + destroy building and infrastructure

89
Q

What has been produced by world’s leading volcanists to save life’s?

A

200 page handbook

90
Q

What is used to manage risks of volcanoes?

A

3 P’s ➡️ prediction, preparation and protection

91
Q

Give a brief summary of how geological observations are used to monitor volcanoes

A

. Slope angle - Tilt meter used to measure changes in volcano’s slope. Inactive volcano = 0 degrees. When magma rises into magma chamber volcano expands casing slope angle to change
. Distance measurements - electronic distance measurements used to measure horizontal movements ➡️ before eruption distance will increase
. Global Positioning System - receivers places along volcano to detect any small changes

92
Q

Give a brief summary of how seismic activity is used to monitor volcanoes

A

. Tremors or earthquakes occur as volcano about to erupt . An increase in seismic activity = greater likelihood of eruption
. Measured using local seismographs measuring severity of earthquake
. Infra sound monitoring ➡️ sub audible below 20Hz
. 60 stations around world to detect + locate erupting volcanoes
. Many found at plate boundaries ➡️ very difficult to observe if seismic activity is related to volcano or general movement of plates

93
Q

Give a brief summary of how gas emissions are used to monitor volcanoes

A

. Magma rising near surface causes pressure decrease = gases escape
. Sulphur dioxide is main component + more amounts show arrival of magma near surface
. May 13th 1991 Mt Pinatubo in Philippines increase may 28th amounts to 5000 tonnes x10 than June 12 1991
. Sulphur dioxide levels drop to low levels before eruption too due to sealing of gas passage by hardened magma
. Measure either at volcano ( in crater by helicopter) or further afield at safer distance from volcano

94
Q

Why are predictions not so good for monitoring volcanoes?

A

It’s only a prediction it may not be accurate and sometimes equipment may not work properly

95
Q

How are past hazards useful to predict volcanoes?

A

. People can figure out how close they are willing to live near volcano. Prevent deaths and injuries

96
Q

How is lava diversion used to prepare to volcanoes?

A

. Lava tubes ➡️ cooled and hardened outer crusts of lava which provide insulation for molten rock inside
. Not suitable because soon spilled again by lava e.g Hilo was instead saved when Mauna Loa stopped erupting

97
Q

What are social effects?

A

Effects that effect people

98
Q

What are economic effects?

A

Effects to do with money

99
Q

What are environmental effects?

A

Things that effect the environment

100
Q

What are political effects?

A

Effects to do with unions or parties

101
Q

What is seismicity?

A

Frequency of earthquakes/ earth shaking in a region
. Can be human induced by mining, fracking e.t.c

102
Q

Where is the focus?

A

In the earth’s crust and is the source of the earthquake

103
Q

Where is the epicentre of an earthquake?

A

Directly above the focus on the surface of the crust and is the strongest point of an earthquake

104
Q

What are seismic waves?

A

Vibrations that travel outward from the focus point

105
Q

What are the steps to seismic waves?

A
  1. Pressure build up where 2 plates meet
  2. Sudden release ( due to rock failure creates waves)
  3. Waves cause ground to shake
  4. Intensity of shaking is dictated by depth of focus and energy release
  5. Result of this is the earthquake hazard
106
Q

What are some characteristics of body waves?

A

. Travel through interior of earth
. Arrive before surface waves are emitted by earthquake
. Higher frequency than surface waves

107
Q

What are some characteristics of surface waves?

A

. Travel through crust only
. Lower frequency than body waves
. Easily distinguished on seismogram
. Arrive after body waves
. Entirely responsible for damage and destruction associated with earthquakes
. Damage and strength of surface waves less in deeper earthquakes

108
Q

What are P -waves (primary)?

A

. Body waves
. Fastest waves
. Move through solids and liquids causing earth to move backwards and forwards

109
Q

What are S- waves (secondary)?

A

. Body waves
. Slower waves
. Move through a sideways motion
. Shake the earth at right angles to direction of travel
. Can’t move through liquids but do much more damage than P-waves

110
Q

What are love waves?

A

. Surface waves which are the slowest
. Cause a sideways motion and the most damage

111
Q

What are Rayleigh waves?

A

. Radiate along the surface
. Low frequency rolling motion

112
Q

What is a tsunami?

A

A large ocean waves that is caused by sudden motion on the ocean floor

113
Q

What can cause a tsunami?

A

. Earthquakes
. Powerful volcanic eruption
. Underwater landslides
. Impact of large meteorite

114
Q

How can subduction zones lead to potential tsunamis?

A

. Caused by earthquakes in subduction zone
. Oceanic plate being forces down into mantle by plate tectonic forces
. Friction between them is huge and plates become ‘stuck’

115
Q

Explain accumulating seismic energy for tsunamis

A

. Stuck plate continues to descend causes a slow distortion of overriding plate
. Energy can accumulate over a long period of time

116
Q

How does an earthquake cause a tsunami?

A

The friction is then released from the 2 plates causing a sudden motion causing a tsunami cause it gives a shove to overlying water

117
Q

How can a tsunami cause flooding?

A

Some of the water travels out and across the ocean basin and at the same time water rushes landward to flood the recently lowered shoreline

118
Q

Do tsunamis travel in one wave?

A

. No
. They are ‘wave trains’ consisting of multiple waves

119
Q

How are tsunamis formed?

A
  1. Rapid movement of ocean floor displaces a column of water
  2. A series of waves travels outward at heights believed to be less than three feet on the open
  3. As a wave approaches land, it’s energy compresses into a smaller space, forcing it to gain height
120
Q

What is liquefaction?

A

The mixing of sand or soil and groundwater during the shaking of a moderate or strong earthquake

121
Q

Where does liquefaction occur?

A

Under buildings
. Buildings may start to lean, tip over or sink several feet

122
Q

What happens after an earthquake for liquefaction?

A

Ground firms up again and the water settles back down to its usual place deeper in ground

123
Q

What may make an area more susceptible to liquefaction?

A
  1. Areas that have groundwater near surface and sandy soil
  2. Loosely packed grains of soil as easier for liquid and water to move into material
124
Q

What causes landslides?

A

Ground shaking due to earthquakes destabilises cliffs and steep slopes causing landslides and rock falls as a significant side effect

125
Q

What are some factors making an area more susceptible to landslides?

A

1.Heavy rain as soil becomes weak
2. Unconsolidated or fractured rock
3. Highland areas - many being fold mountains on unstable plate boundaries
4. Relief rainfall in upland areas means ground is significantly more likely to become saturated and fall

126
Q

What often occurs during earthquakes?

A

Subsidence and lowering of ground surface

127
Q

Give a brief summary of how past seismic records are used to predict earthquakes

A

. Earthquakes often occur in intervals from one another
. Scientists can record last earthquake and look at last earthquake dates in order to try and figure out when another earthquake will occur
. Look at magnitude scale

128
Q

Give a brief summary of how remote sensing is used to predict earthquakes

A

. Use so satellites which monitor definition in crust due to magma rising up
. Changes in temperature on surface could indicate earthquake
. Sensors on earth monitor the shaking as well for scientists - deformities in ground picked up by satellites

129
Q

Give a brief summary of how gas emissions are used to predict earthquakes

A

. Random gas detected as gas is emitted through cracks developing in crust suggesting an earthquake
. Reductions in pressure allow radon gas to escape to the surface
. Random gas detectors will pick this up and alert people

130
Q

What other methods are used to try and predict earthquakes?

A
  1. Animal behaviour- animals often act strange when they can sense an earthquake about to come due to seismic waves
  2. Groundwater levels - change rise and fall of groundwater just before earthquake
  3. Seismometer- measure tiny vibrations within the ground cause by plate movement
131
Q

What machines are used to predict earthquakes?

A

Seismometers which are used to plot a seismograph which can be read to determine how much of earth is shaking

132
Q

What does the Mercalli scale measure?

A

Effects of earthquake + experience

133
Q

How’s does the Mercalli scale work?

A

. Low numbers of intensity scale = manner in which how earthquake felt by people
. High numbers = based on observed structural damage
. Scale from 1 - 12
. Very subjective and vary scale for different people

134
Q

What does the Richter scale measure?

A

Measures the ground deformation + energy released by earthquake

135
Q

What is the Richter scale?

A

. A LOGARITHMIC SCALE and therefore 3 is 10x greater than 2 rather than just 1

136
Q

What does the Richter scale show?

A

. As you move up Richter scale frequency of earthquake decreases
. Due to more and more pressure being built up and then released

137
Q

Why do new agencies use the Richter scale?

A

. More reliable and accurate
. Mercalli scale based more on experience and is more subjective

138
Q

What have geologists recently come up with to measure earthquakes?

A

. The Moment Magnitude scale
. Identifies energy released by earthquake , same scale as Richter scale 1-10

139
Q

What is a tropical storm?

A

A violent rotating storm which occurs at the mid latitudes ( the tropics)

140
Q

What are tropical storm names based on?

A

Location
America - hurricane
Asia - Typhoon
Indian Ocean- cyclones

141
Q

What is the distribution of tropical storms?

A

. Generally found between Topic of Cancer and Tropic of Capricorn
. Found mainly in Indian, Atlantic and Pacific oceans
. Occur at coastline of continents
. Move towards continents then die out as they loose energy on land

142
Q

What is the reason for distribution of tropical storms?

A

. Sea temperature has to be 27 degrees or above

143
Q

What is the geographical factor that puts you at risk from a tropical storm?

A

. Living near a coastline - more likely to experience a tropical storm

144
Q

What are the features of a tropical storm?

A
  1. Eye - centre of the storm
  2. Eyewall - storm clouds surrounding the eye
  3. Bands of thunderstorms
145
Q

How are tropical storms formed?

A
  1. Strong upward movement of air draws water vapour up from 26-27 degree warm ocean surface
  2. The evaporated air cools as it rises and condenses to form towering thunderstorm clouds
  3. Condensing air releases energy which powers the storm and draws up more water
  4. Several thunderstorms combine to from a giant spinning storm. Surface winds exceed 120km/h and a tropical storm is officially born
  5. Storm develops an eye where air rapidly descends. Most intense (strongest winds) found in eyewall on edge of eye
  6. Storm is carried across the warm ocean it gradually gathers strength and energy
  7. Upon landfall the storm’s energy supply is cut off/ friction with land slows and weakens it. If the storm reaches warm water again it may regain some strength again
146
Q

What is the Coriolis effect?

A

Caused by the Coriolis force which deflects objects within a rotating system

147
Q

What happens in the Northern hemisphere due to the Coriolis effect?

A

Objects deflect to the right in the Northern Hemisphere

148
Q

What happens in the Southerm hemisphere due to the Coriolis effect?

A

Objects deflect to the left in Southern hemisphere

149
Q

What may cause the frequency of tropical storms to increase?

A

. Increasing sea temperatures ➡️ more fossil fuels burnt + deforestation + climate change

150
Q

What are the conditions needed for a tropical storm to form?

A
  1. Sea temperature of 26 degrees +
  2. Sea temperature to an ocean depth of 70m ➡️ plenty of evaporation to keep storm going
  3. Low wind shear in upper atmosphere ➡️ allow circulation of storm to develop
  4. Location at least 5 degrees North or South of equator ➡️ so Coriolis force is present ( very weak at equator so will not create spinning system)
  5. Low level convergence of air in lower atmosphere ➡️ winds need to come together near centre of low pressure zone so can rise
151
Q

How do we predict tropical storms?

A

. Certain months of the year have tropical storms ➡️ near Madagascar storm happen between December and March
. Central tracks of storm help us predict where storm will go
. Tropical storm maps ➡️ show frequency+ predict where storm will go

152
Q

How do we monitor tropical storms?

A
  1. Aircrafts and drones ➡️ discover eye of storm and surrounding eyewall by releasing dropsondes feeding data back to meteorologists and help to evacuate people
  2. Satellites ➡️ measure temperature inside storm, cloud heights, rain,snow, wind speeds. Some very advanced satellites measure ‘ hot towers’ to see if storm is intensifying or not
  3. Computer models ➡️ computer algorithms can analyse satellite images for hot towers and use data from other sources to provide a reliable, detailed source of information
153
Q

What scale is used to measure tropical storms?

A

Saffir- Simpson scale
. 1-5 scale

154
Q

What are the features of category 1 tropical storms?

A

. 74-95 mph winds sustained
. Very dangerous winds will produce some damage

155
Q

What are the features of category 2 tropical storms?

A

. 96- 110 mph winds sustained
. Extremely dangerous winds will cause extensive damage

156
Q

What are the features of category 3 tropical storms?

A

. 111- 129 mph winds sustained
. Devastating damage will occur

157
Q

What are the features of category 4 tropical storms?

A

. 130- 156 mph winds sustained
. Catastrophic damage will occur

158
Q

What are the features of category 5 tropical storms?

A

. 157 mph or higher winds sustained
. Catastrophic damage will occur

159
Q

What is a storm surge?

A

A rise in sea level that occurs during tropical storms. The storms produce strong winds that push water inshore leading to flooding

160
Q

What areas are particularly at risk from storm surges?

A

Coastal areas

161
Q

What other factors make storm surge worse?

A
  1. Atmospheric pressure
  2. The width and slope of the area itself
162
Q

What are strong winds?

A

Air that is circulating the tropical storm itself and found in the storm surge

163
Q

What areas are at risk from strong winds particularly?

A

. Coastal areas + big cities on coast more at risk
. Low income countries

164
Q

What other factors make strong winds worse?

A

. Low income countries ➡️ weak infrastructure
. Coriolis effect makes it worse
. Can reach up to 150mph

165
Q

What is a landslide?

A

A collapse of a mass of earth or rock from a mountain or cliff

166
Q

What areas are more at risk to landslides?

A

Steep terrains, land burnt by wildfires, land modified by humans

167
Q

What factors can make landslides worse?

A

Repeated freezing+ thawing + volcanic eruptions

168
Q

What causes landslides?

A

Disturbances in natural stability of slope ➡️ accompany droughts + heavy flooding + rainfall from tropical storms = saturated rock + soil

169
Q

What is river flooding/ heavy rainfall?

A

When water level in river, lake, stream rises+ overflows into surrounding land

170
Q

What causes river flooding/ heavy rainfall?

A

As air rises from tropical storm quickly spirals upwards, cools and condenses and large clouds are formed ➡️ eyewall formed = heavy rain

171
Q

What areas are particularly at risk from river flooding/ heavy rainfall?

A

. Settlements near riverbanks
. People + houses on flatter ground

172
Q

What factors make river flooding/ heavy rainfall worse?

A

. Heavy rainfall
. Saturated soil
. Strong winds

Physical Geography A Level 🌋🌊🔥 (3 decks)

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