Natural Hazards 🔥🌊🌋🌲 Flashcards
1
Q
What are the different types of hazards?
A
. Earthquakes
. Tropical storms
. Volcanoes
. Tsunamis
. Landslides
. Flooding
. Heatwaves
. Heavy snow
2
Q
What is hazard risk?
A
The probability or chance that a natural hazard may take place
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
4
Q
What are the factors influencing hazard perception?
A
- Cultural factors ➡️ indigenous settlers not exposed to warnings, certain people more exposed to war msg as happened for hundreds of years
- Economic factors ➡️ certain people more educated in rich countries, people can have better infrastructure and warning systems if wealthy
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
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
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?
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
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
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
11
Q
What does the park model show?
A
- Immediate responses after hazard has occurred ➡️ rescue teams, charity help
- Rehabilitation ➡️ efforts made to restore and community structures at least temporarily
- Reconstruction ➡️ permanent changes introduced to restore quality of life
. Larger the dip the worse economy is effected
. Also called disaster response model
12
Q
What are some factors influence the park mode?
A
- Economic development ➡️ lack of building infrastructure, prevention methods
- Education ➡️ more people educated better the response
- State of the country ➡️ LIC’s more likely to receive help from countries
. HIC’s have people who can help internally
13
Q
What does the Hazard management cycle say?
A
- Hazard event + Risk ➡️ hazard severity probability
- Response ➡️ rescue and evacuation+ relief + external support
- Recovery ➡️ long term recovery:internal and reconstruction process
- Prevention / mitigation ➡️ ongoing process to lessen severity of hazard on people / property
- Preparation ➡️ actions prior to event to activate necessary resources
. Cyclical movement as no natural hazard is guaranteed once
14
Q
What is the lithosphere?
A
The solid top layer of crust in which plates are formed consists of crust and upper mantle
15
Q
What is the asthenosphere?
A
Soft, plastic like rock in the upper mantle just below the lithosphere
16
Q
What is the process by which earth makes heat?
A
Radioactive decay
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
18
Q
What is happening to earth now?
A
Earth is cooling now but very slowly and it is close to a steady temperature
19
Q
What are the waves called that travel from an earthquake?
A
Seismic waves
20
Q
How does radioactive decay work?
A
. Produces subatomic particles that zip away
. These later collide with surrounding material inside earth
21
Q
What’s earth’s core temperature estimated to be?
A
Around 5,000-7,000 degrees Celsius
22
Q
How long did Wagener think the plate movement has taken since Pangea formed?
A
300 million years
23
Q
What was found when the mid-oceans were mapped?
A
. Mid ocean ridges ➡️ new ocean floor being created
24
Q
What did Wagener initially struggle to explain?
A
Physically how the plates could move
25
As well as climate and landscape what else proved the theory?
Fossils on different continents and how the plates all fit into each other
26
When it refers to the crust being in pieces what are these ‘pieces’?
The continent pieces of the earth ➡️ tectonic plates
27
Explain convection currents
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
28
What is the jigsaw fit for plate tectonics?
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
29
What is the Geological fit in terms of plate tectonics?
. 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
30
What is the tectonic fit in terms of plate tectonics?
. 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
31
What are glacial deposits in terms of plate tectonics?
. 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
32
What is fossil evidence in terms of plate tectonics?
. 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
33
What is the idea of paleomagnetism?
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
34
What is ridge push?
The process of material pushing out from the ridge
35
What are subduction zones?
Gravity ‘pulls’ the ocean plate down into the mantle. This destroys crust material and keeps earth in shape
36
What is slab pull?
Pull on a plate being subducted
37
What are some features of continental crusts?
.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
38
What are some features of oceanic crusts?
. Thickness = 6-10km
. Age = less than 200 million years old
. Density = 3.0g/m (denser)
. Mineral content = mainly silicon, magnesium, oxygen
. Rock type = basalt
39
What is an example of a destructive plate margin?
Indo- Australian+ pacific plate
40
What is an a example of a constructive plate margin?
North American plate and Cocos plate
41
What happens at constructive plate margins?
Plates move apart from each other
42
What are some tectonic features at constructive plate margins?
. Rift valleys
. Ocean trenches
. Made ocean ridges
. Volcanoes
43
What are some examples of tectonic features at constructive plate margins?
. African rift valley
. Mid Atlantic ridge
44
What happens at destructive subduction plate margins
Denser oceanic plate subducts below the light continental crust
45
What tectonic features form at oceanic oceanic destructive plate margins?
. Submarine volcanoes
. Earthquakes
. Ocean ridges
. Island arcs
46
What tectonic features form at oceanic continental destructive plate margins ?
. Earthquakes
. Volcanoes
. Young fold mountains
. Ocean trenches
47
What are some examples of oceanic oceanic destructive plate margins?
. Mariana Trench
. Japan pacific plate
48
What are some examples of oceanic continental destructive plate margins?
. Chile and Peru trench on the Nazca plate
. Atacama trench
49
What happens in collision plate boundaries?
2 continental plates move together
50
What forms at collision plate boundaries?
. Young fold mountains
. Powerful earthquakes
51
What is an example of collision plate boundaries?
The Himalayans
52
What happens at conservative plate boundaries?
2 plates collide and slide past each other causing friction
53
What are some tectonic features at conservative plate margins?
. Earthquakes
. Fault lines
. Tsunamis
. Ocean ridges
54
What is an example of a conservative plate margin?
. San Andreas fault line in California
55
How are mid Atlantic ridges formed?
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
56
How are rift valleys formed?
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
57
How are horsts and grabens formed?
Conventional currents in asthenosphere cause extensions of crust. As crust extends garbens (down dropped blocks) and horses (up thrown blocks)are formed
58
What are at conservative plate margins?
Though almost invisible large fault line around conservative margins can be visible ➡️ San Andreas fault in California
59
Why may conservative plate margins be considered the most deadly?
. 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
60
What can be used to predict earthquakes?
Seismic monitoring uses sensitive seismographs to record ground motion from seismic waves created by earthquake
61
What are the 3 types of destructive/ convergent plate margins?
1. Oceanic plate moves towards continental plate
2. Oceanic plate moves towards oceanic plate
3. Continental plate moves towards continental plate
62
What are the location of earthquakes and volcanoes on a world map?
. 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
63
What are hotspots?
. 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
64
What are some features of a composite volcano?
. 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
65
What are some features of a shield volcano?
. 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
66
What does viscosity mean?
Viscosity of liquid a measure of its resistance to flow thus low resistance = runny liquid state and Hugh resistance = thick sticky half liquid state
67
What affects magma viscosity?
Silica content in the magma
68
What are the 6 types of eruptions?
1. Icelandic
2. Hawaiian
3. Strombolian
4. Plinian
5. Vulcanian
6. Pelean
69
Describe pelean eruptions
. Explosive eruptions
. Range of tephra
. Nuee ardent (glowing clouds)
. Pyroclastic flows
70
Describe Hawaiian eruptions
. Effusive
. Minor explosively with fire fountain
. Low viscosity lava
71
Describe Strombolian eruptions
. Gas bubbles
. Eject tephra (ash and lapilli)
72
Describe Vulcanian eruptions
. Higher gas build up than Strombolian
. Highly viscous lava
. Series of short lived explosions with tephra including bombs
73
Describe Icelandic eruptions
. Low viscosity
. Highly effusive
. May have water therefore phreatic
74
Describe plinian eruptions
. Highly explosive
. Large eruption column (up to 45km)
. Range of tephra
. Pyroclastic fallout including flows
75
What is used to measure the explosively of a volcano?
The volcanic explosivity index
. Goes from 0-8
76
What are primary effects?
Effects that occur immediately along with the event
77
What are secondary effects?
Direct consequences of the event but not immediate
78
Is there a high chance of you being killed by an earthquake?
No it’s fairly small
79
What makes volcanoes deadly?
Other hazards associated with it can be deadly and lead to huge amount of deaths + injuries
80
Give a brief summary about lahars
. 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
Give a brief summary of mudflows
. 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
Give a brief summary of tephra
. 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
Give a brief summary of nuées Ardentes
. 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
Give a brief summary of lava flows
. 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
Give a brief summary of volcanic gases
. 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
Give a brief summary of acid rain
. 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
Give a brief summary of ash fallout
. 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
Give a brief summary of Pyroclastic flows
. 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
What has been produced by world’s leading volcanists to save life’s?
200 page handbook
90
What is used to manage risks of volcanoes?
3 P’s ➡️ prediction, preparation and protection
91
Give a brief summary of how geological observations are used to monitor volcanoes
. 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
Give a brief summary of how seismic activity is used to monitor volcanoes
. 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
Give a brief summary of how gas emissions are used to monitor volcanoes
. 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
Why are predictions not so good for monitoring volcanoes?
It’s only a prediction it may not be accurate and sometimes equipment may not work properly
95
How are past hazards useful to predict volcanoes?
. People can figure out how close they are willing to live near volcano. Prevent deaths and injuries
96
How is lava diversion used to prepare to volcanoes?
. 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
What are social effects?
Effects that effect people
98
What are economic effects?
Effects to do with money
99
What are environmental effects?
Things that effect the environment
100
What are political effects?
Effects to do with unions or parties
101
What is seismicity?
Frequency of earthquakes/ earth shaking in a region
. Can be human induced by mining, fracking e.t.c
102
Where is the focus?
In the earth’s crust and is the source of the earthquake
103
Where is the epicentre of an earthquake?
Directly above the focus on the surface of the crust and is the strongest point of an earthquake
104
What are seismic waves?
Vibrations that travel outward from the focus point
105
What are the steps to seismic waves?
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
What are some characteristics of body waves?
. Travel through interior of earth
. Arrive before surface waves are emitted by earthquake
. Higher frequency than surface waves
107
What are some characteristics of surface waves?
. 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
What are P -waves (primary)?
. Body waves
. Fastest waves
. Move through solids and liquids causing earth to move backwards and forwards
109
What are S- waves (secondary)?
. 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
What are love waves?
. Surface waves which are the slowest
. Cause a sideways motion and the most damage
111
What are Rayleigh waves?
. Radiate along the surface
. Low frequency rolling motion
112
What is a tsunami?
A large ocean waves that is caused by sudden motion on the ocean floor
113
What can cause a tsunami?
. Earthquakes
. Powerful volcanic eruption
. Underwater landslides
. Impact of large meteorite
114
How can subduction zones lead to potential tsunamis?
. 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
Explain accumulating seismic energy for tsunamis
. Stuck plate continues to descend causes a slow distortion of overriding plate
. Energy can accumulate over a long period of time
116
How does an earthquake cause a tsunami?
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
How can a tsunami cause flooding?
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
Do tsunamis travel in one wave?
. No
. They are ‘wave trains’ consisting of multiple waves
119
How are tsunamis formed?
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
What is liquefaction?
The mixing of sand or soil and groundwater during the shaking of a moderate or strong earthquake
121
Where does liquefaction occur?
Under buildings
. Buildings may start to lean, tip over or sink several feet
122
What happens after an earthquake for liquefaction?
Ground firms up again and the water settles back down to its usual place deeper in ground
123
What may make an area more susceptible to liquefaction?
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
What causes landslides?
Ground shaking due to earthquakes destabilises cliffs and steep slopes causing landslides and rock falls as a significant side effect
125
What are some factors making an area more susceptible to landslides?
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
What often occurs during earthquakes?
Subsidence and lowering of ground surface
127
Give a brief summary of how past seismic records are used to predict earthquakes
. 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
Give a brief summary of how remote sensing is used to predict earthquakes
. 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
Give a brief summary of how gas emissions are used to predict earthquakes
. 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
What other methods are used to try and predict earthquakes?
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
What machines are used to predict earthquakes?
Seismometers which are used to plot a seismograph which can be read to determine how much of earth is shaking
132
What does the Mercalli scale measure?
Effects of earthquake + experience
133
How’s does the Mercalli scale work?
. 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
What does the Richter scale measure?
Measures the ground deformation + energy released by earthquake
135
What is the Richter scale?
. A LOGARITHMIC SCALE and therefore 3 is 10x greater than 2 rather than just 1
136
What does the Richter scale show?
. As you move up Richter scale frequency of earthquake decreases
. Due to more and more pressure being built up and then released
137
Why do new agencies use the Richter scale?
. More reliable and accurate
. Mercalli scale based more on experience and is more subjective
138
What have geologists recently come up with to measure earthquakes?
. The Moment Magnitude scale
. Identifies energy released by earthquake , same scale as Richter scale 1-10
139
What is a tropical storm?
A violent rotating storm which occurs at the mid latitudes ( the tropics)
140
What are tropical storm names based on?
Location
America - hurricane
Asia - Typhoon
Indian Ocean- cyclones
141
What is the distribution of tropical storms?
. 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
What is the reason for distribution of tropical storms?
. Sea temperature has to be 27 degrees or above
143
What is the geographical factor that puts you at risk from a tropical storm?
. Living near a coastline - more likely to experience a tropical storm
144
What are the features of a tropical storm?
1. Eye - centre of the storm
2. Eyewall - storm clouds surrounding the eye
3. Bands of thunderstorms
145
How are tropical storms formed?
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
What is the Coriolis effect?
Caused by the Coriolis force which deflects objects within a rotating system
147
What happens in the Northern hemisphere due to the Coriolis effect?
Objects deflect to the right in the Northern Hemisphere
148
What happens in the Southerm hemisphere due to the Coriolis effect?
Objects deflect to the left in Southern hemisphere
149
What may cause the frequency of tropical storms to increase?
. Increasing sea temperatures ➡️ more fossil fuels burnt + deforestation + climate change
150
What are the conditions needed for a tropical storm to form?
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
How do we predict tropical storms?
. 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
How do we monitor tropical storms?
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
What scale is used to measure tropical storms?
Saffir- Simpson scale
. 1-5 scale
154
What are the features of category 1 tropical storms?
. 74-95 mph winds sustained
. Very dangerous winds will produce some damage
155
What are the features of category 2 tropical storms?
. 96- 110 mph winds sustained
. Extremely dangerous winds will cause extensive damage
156
What are the features of category 3 tropical storms?
. 111- 129 mph winds sustained
. Devastating damage will occur
157
What are the features of category 4 tropical storms?
. 130- 156 mph winds sustained
. Catastrophic damage will occur
158
What are the features of category 5 tropical storms?
. 157 mph or higher winds sustained
. Catastrophic damage will occur
159
What is a storm surge?
A rise in sea level that occurs during tropical storms. The storms produce strong winds that push water inshore leading to flooding
160
What areas are particularly at risk from storm surges?
Coastal areas
161
What other factors make storm surge worse?
1. Atmospheric pressure
2. The width and slope of the area itself
162
What are strong winds?
Air that is circulating the tropical storm itself and found in the storm surge
163
What areas are at risk from strong winds particularly?
. Coastal areas + big cities on coast more at risk
. Low income countries
164
What other factors make strong winds worse?
. Low income countries ➡️ weak infrastructure
. Coriolis effect makes it worse
. Can reach up to 150mph
165
What is a landslide?
A collapse of a mass of earth or rock from a mountain or cliff
166
What areas are more at risk to landslides?
Steep terrains, land burnt by wildfires, land modified by humans
167
What factors can make landslides worse?
Repeated freezing+ thawing + volcanic eruptions
168
What causes landslides?
Disturbances in natural stability of slope ➡️ accompany droughts + heavy flooding + rainfall from tropical storms = saturated rock + soil
169
What is river flooding/ heavy rainfall?
When water level in river, lake, stream rises+ overflows into surrounding land
170
What causes river flooding/ heavy rainfall?
As air rises from tropical storm quickly spirals upwards, cools and condenses and large clouds are formed ➡️ eyewall formed = heavy rain
171
What areas are particularly at risk from river flooding/ heavy rainfall?
. Settlements near riverbanks
. People + houses on flatter ground
172
What factors make river flooding/ heavy rainfall worse?
. Heavy rainfall
. Saturated soil
. Strong winds
