Earth And Natural Disaster Flashcards
(112 cards)
1
Q
what is a natural event?
A
a natural event is a physical occurrence caused by natural processes of the Earth such as an earthquake or volcano
2
Q
what is a natural hazard?
A
an event or process that threatens to cause damage and destruction to people, their property and settlements
3
Q
what is a natural disaster? what is the criteria?
A
- natural disaster = when a hazard causes erious damage or destruction
- criteria: 10 or more human deaths, 100 or more affected/injured/made homeless, country declares a state of emergency or appeals for international aid
4
Q
name some geological hazards
A
- earthquakes
- volcanic eruptions
- landslides
- tsunamis
5
Q
name some climatic hazards
A
- drought
- flood
- storms
- hurricanes
6
Q
name some biological hazards
A
- pests
- disease - mosquitos are a vector that transport malaria between humans
- fire
- mass extinction
7
Q
name some technological hazards
A
- transport accident
- pollution
- nuclear explosion
- genocide/ deforestation
8
Q
exposure vs vulnerabilty
A
- exposure = where people are present to directly experience a natural hazard and are in harm’s way
- vulnerability = when a population is susceptible to the negative impacts of a natural hazard due to poor damage control and recovery (often related to development level of a country)
9
Q
define risk and risk assessment
A
- risk = the likelihood of a hazardous event occurring x potential severity of its damage
- risk management = judgement of the degree of damage and destruction that an area may experience as a result of a natural event
10
Q
define mitigation
A
the reduction of the risk posed by a hazard through action taken to adjust and cope with a situation
11
Q
why are some places more hazardous than others?
A
- some are better able to cope with damaging impacts of hazards by the installation of infrastructure (flood-barriers, earthquake-resistant buildings)
- some places the hazards are stronger + more destructive than others (earthquakes on ring of fire to Japan)
- some experience natural hazards more frequently than others
- some places experience more than one type of natural hazard event
12
Q
What is a tropical cyclone?
A
An area of very low air pressure which bring torrential (fast and heavy) rain, thunder and lightning and very strong winds
13
Q
Where do tropical storms occur and why here?
A
Tropical or sub-tropical waters - 5-15 degrees north and south of equator - bc the temperature is high enough to form cyclones, has Coriolis force, wind shear and there is low atmospheric pressure
14
Q
Where are tropical storms called hurricanes, and when do they occur there?
A
- hurricane- Atlantic ocean, Caribbean sea, eastern Pacific Ocean : June-November
15
Q
Where are tropical storms called cyclones, and when do they occur there?
A
- cyclone- Indian Ocean, Bay of Bengal: June-November (northern hemisphere) + November-April (southern hemisphere)
16
Q
Where are tropical storms called typhoons, and when do they occur there?
A
- typhoons - Western Pacific Ocean : June-December (northern hemisphere) + January-March (southern hemisphere)
17
Q
Name factors affecting the formation of tropical cyclones
A
- ocean temperature
- atmospheric pressure
- wind shear
- Coriolis force
18
Q
Explain how ocean temperature affects formation of tropical cyclones
A
- High sea surface temperatures exceeding 27 degrees +depth of 60m
- High rates of evaporation above the ocean create a warm, humid atmosphere
- This is necessary to provide vast amounts of heat energy and moisture to fuel the growth of a hurricane
19
Q
Explain how low atmospheric pressure affects formation of tropical cyclones
A
- created by air rising upwards from ocean surface
- cooling and condensation lead to cloud formation
- condensation releases latent heat, providing further energy for the developing storm
20
Q
Explain how wind shear affects formation of tropical cyclones
A
- if too strong,or if there is too much variation in speeds+direction at different altitudes
- embryonic cyclone can be broken up before it has chance to develop
21
Q
Explain how coriolis force affects formation of tropical cyclones
A
- created by rotation of the Earth on its axis, it causes moving masses of air or liquid to deflect from their course
- once the areas of low pressure in the tropical waters reach a certain size, the Coriolis force will start to rotate anti clockwise in northern hemisphere +clockwise in southern hemisphere, creates spiral shape
- Coriolis is zero on equator, and increases in strength the further away from it you go
22
Q
structure of tropical cyclones
A
- Eye: narrow area of subsiding air at centre of hurricane- around which the storm system rotates
- Eye wall: region surrounding the Eye, most destructive energy in hurricane with strongest winds and heaviest rain
- Cumulonimbus clouds- bringing torrential rain,thunder and lightning
- vigorous upward spiral of warm humid air fuels the storm
23
Q
What are the stages of a tropical cyclone + characteristics it must have to be called this?
A
- Early/ weak stages - TROPICAL DEPRESSION
- TROPICAL STORM - sustained wind speeds of 39mph
- TROPICAL CYCLONE- wind speeds reach 74mph
24
Q
Weather changes experienced at approach of hurricane
A
- Approach: temperature and pressure begin to fall. Clouds begin to form + showers develop- wind begins to gust
25
Weather changes experience before eye passes over
- Before the eye: pressure falls rapidly, wind speeds increase up to hurricane force speed, strongest at eye wall. Cumulonimbus clouds with thunder + torrential rain (up to 250mm/day)
26
Weather changes experienced as eye passes over
Eye: period of calm. Pressure very low. Temperatures rise and sky clears briefly
27
Weather changes experienced after the eye passes over
- after eye- winds from southeast (usually strongest in storm), especially in eye wall. Cumulonimbus clouds- torrential rain. Temperature drops again but pressure begins to rise
28
Weather changes experienced at end of hurricane
End: temperature + pressure rises. Rain decreases to showers + winds decrease
29
Name tropical storm hazards
- strong winds
- heavy rainfall
- storm surge
- flooding
- landslides
- disease
30
Tropical storm hazards - winds
- have sustained wind speeds of at least 74 mph, but often higher.
- Atmospheric instability can trigger tornadoes within a cyclone, creating additional wind hazard on local scale.
- High winds- destroy trees, crops, buildings, transport links, power supplies and communication.
- Airborne debris can be lethal.
31
Tropical storm hazards - rainfall
- torrential rain can lead to serious inland flooding
- Secondary hazards of rainfall= landslides+ mudslides on saturated slopes
- Flood water can lead to disease due to contamination with sewage or act as a breeding ground for mosquitoes (malaria)
32
Tropical storm hazards - storm surges
- extremely low atmospheric pressure causes the sea surface to expand upwards, forming a dome of water.
- As the tropical cyclone is driven onshore, this bulge of water is driven onshore.
- With extremely high waves, storm surge floods low-lying coastal areas and causes damage to coastal infrastructure.
- contain a lot of debris-making it more lethal
33
Which scale is used to measure the intensity of a storm?
- Saffir-Simpson scale
- classified by wind speeds, surface pressure and height of a storm surge
- 1-5 categories with 5 the worst one
34
Name the 3 methods of monitoring weather conditions in a tropical cyclone
- weather stations
- radar
- satellites
35
Monitoring weather conditions in tropical cyclones - weather stations
- track movements + characteristics of tropical storms providing information on cyclone
- including pressure, temperature, humidity, wind speed and direction
- however, can be damaged by winds, creating data gaps so a more mobile alternative is a weather reconnaissance plane
36
Monitoring weather conditions in tropical cyclones - radar
- measures reflected sound waves: sound waves broadcast from a radar mast, come into contact with moving object (rain cloud), bounce back to mast and are measured
- gives information of the cloud's direction, speed of movement and density of water droplets (rain potential)
37
Monitoring weather conditions in tropical cyclones - satellites
- show cloud formations using visible light cameral, infrared can detect heat energy contained within a storm
- no gaps in coverage and no risk of storm damage
38
Order of the 4 parts of the earth
1. Crust
2. Mantle
3. Outer core
4. Inner core
39
Crust
- thinnest layer
- only 8-65km thick
- made of less dense rock so floats on mantle
40
Mantle
- thickest part of earth
- 2900km thick + denser than crust
- upper mantle is rigid but lower mantle is semi-molten and has convection currents
41
Outer core
- 2200km thick
- made out of molten iron and nickel
42
Inner core
- made of solid iron and nickel
- densest layer of earth because is under immense amts of pressure
- 1260km thick
43
What 2 layers is the lithosphere made of?
Crust + upper mantle
44
Constructive margin
- plates diverge (move away from each other)
- can form volcanos bc of rising magma
45
Destructive margin
- occur between a continental + oceanic crust plate
- converging (move towards each other)
- oceanic plate subducts under the continental as its denser
- plates can get stuck underneath each other and when they slip it’s releases lots of pressure creating earthquakes and fold mountains (volcanoes as there’s rising magma)
46
Collision margin
- occurs when 2 continental plates converge
- both plates of equal density so they stay at same level
- fold mountains are created w no lava bc there’s no rising magma underneath
47
Conservative margin
- plates move alongside each other
- plates can stick together and friction builds up. When the friction is released, it’s can release as a large earthquake
- no volcanoes as there’s no rising magma
48
Plate margin
The line where 2 adjacent tectonic plates meet
49
Focus
The point underground where plates slip and the seismic waves come from
50
Epicentre
The point directly above the focus on the surface.
51
Liquefaction
When soft sediment like mud can behave like a liquid when shaken by seismic waves
52
What is a primary hazard?
a hazard that is caused immediately by event
53
Secondary hazard of volcanic eruptions/earthquakes
A delayed hazard that was caused by the volcano/ earthquake and was more of the aftermath of the event. eg liquefaction, tsunamis, pyroclastic flow
54
Stratovolcanoes - found on constructive or destructive margins?
Found in destructive margins such as those of the pacific ring of fire
55
Stratovolcanoes - do they have acidic or basic lava?
Acidic lava
56
Stratovolcanoes - explosive or effusive eruptions?
Eruptions are explosive and infrequent as the lava can get stuck in the vents and explode strongly from a pressure buildup
57
Stratovolcanoes - what is another name for them?
Composite cone, as its formed out of many layers of solidified lava and compressed ash
58
Stratovolcanoes - what type of base and slope do they have?
They have a narrow base and a steep slope as lava doesn’t travel very far from the base before solidifying
59
Shield volcano - found on constructive or destructive margins?
Found on constructive margins
60
Shield volcano - what type of base and slope does it have?
Very wide base and gentle slopes as lava travels very far from vent before solidifying
61
Shield volcanoes - are eruptions effusive or explosive?
Explosions are effusive and frequent
62
Shield volcano - does it have acidic or basic lava?
Basic lava
63
Acidic lava - high or low viscosity?
High viscosity and sticky lava that doesn’t travel far from the vent before solidifying
64
Acidic lava - high or low temperature?
Relatively low temperature of 800ºC
65
Basic lava - high or low viscosity?
Low viscosity and runny lava and it travels very far from vent before solidifying
66
Basic lava - high or low temperature?
High temperatures of 1200ºC
67
Continental crust - more or less dense?
Less dense crust
68
Continental crust - what on earth does it make up?
It makes up the earth’s landmasses
69
Continental crust - how thick is it?
30-50km thick
70
Continental crust - what is it mostly made of?
It’s mostly made of granite
71
Oceanic crust - more or less dense?
More dense
72
Oceanic crust - how thick is it?
Average 7km thick
73
Oceanic crust - what on earth does it make up?
It forms the earth’s sea floor
74
Oceanic crust - what’s it mostly made out of?
Basalt
75
Give 3 reasons why people would live in areas of volcanic hazards
- volcanic ash breaks down to form fertile soil, making it easier and better to farm on
- people may be unaware that they live anywhere that’s hazardous (e.g a dormant volcano for 100s of years)
- people’s family have lived in a hazardous area for generations - a strong tie is developed that makes them reluctant to move elsewhere
76
Primary hazard of earthquakes and volcanoes example
EQ = shaking + displacement caused by seismic waves
V = pyroclastic flow, volcanic bombs, lava flow
77
Secondary hazards of earthquakes and volcanoes examples
EQ = landslides, liquefaction and avalanches + tsunamis
V = Lahar, Jokulhaup, tsunamis, climate change
78
Describe the global distribution of earthquakes and volcanoes
- Unevenly distributed around the Earth's surface
- Clustered in linear belts which correspond to the positions of plate margins
- Earthquakes are found on all margin types, but mainly destructive margins that surround the Pacific Ocean
- Volcanoes are only found on constructive and destructive margins, the Pacific Ring of Fire is the belt of volcanoes which surrounds the Pacific Ocean
- Volcanoes are found away from plate margins as well (hotspot)
79
What is a hotspot volcano?
a volcano which doesn’t occur near a plate boundary
80
Name the earth’s major tectonic plates from left to right
- pacific plate on the left + right with destructive margin
- North American plate with constructive on RHS and destructive on the base
- Nazca plate in between SA plate and pacific plate - constructive plate margin everywhere except the RHS with destructive
- South American plate - constructive margin everywhere except the LHS with destructive
- African plate - constructive margin everywhere except top with collision
- Eurasian plate has collision margin from bottom of Spain to top of India, becomes destructive near Myanmar
- Indo-Australian plate - under Eurasian with constructive margin LHS + base but destructive in RHS and collision on top left
81
How do hotspots work ?
- hot magma plume rises through starmantle and breaks through the weak + thin oceanic crust to form a volcano
- islands start as underwater volcanoes but layers of lava solidify, allowing them to grow and surface
- big island / Kilauea is currently over the hotspot and is active
- pacific plate moves NW = older islands move off hotspot and become extinct by eroding into seamounts
- an example of this is the emperor seamount chain near Japan
81
Example of hotspot
Hawaiian Islands in Pacific Ocean
82
83
Define active, dormant and exctinct volcano
- active = volcano that has erupted in the last 10,000 yrs and is expected to erupt again (1500 currently)
- dormant = volcano that hasn’t erupted for at least 10,000 years but has potential to erupt again
- extinct = volcano that cannot erupt again as it has been cut off from a source of rising magma
84
What is the scale used to measure the magnitude of volcanic eruptions?
- VEI = volcanic explosivity index
- ranges from 1-8
- based off the volume of ash emitted and height eruption column reaches into the atmosphere
- logarithmic = each category is tenfold worse than the last
85
Name the parts of volcanoes
- magma chamber
- layers of composed ash/ solidified lava
- vent
- parasitic/secondary cone
- lava flow
- crater
- ash cloud
86
Magma chamber
Reservoir of molten rock within earth’s crust beneath a volcano
87
Layers of compressed ash/solidified lava
Products of reovirus eruptions layered on top of each other
88
Vent
The pipe up which the magma travels from the magma chamber to the surface
89
Parasitic cone/ secondary cone
Smaller cone that develops on flank of main cone, formed and. The main vent is blocked and magma travels along a secondary vent
90
Lava flow
Molten rock that flows across rhe earth’s surface from the vent
91
Crater
Steep-sided depression at volcano summit created by collapse of rock during eruptions
92
Ash cloud
Fragments of rock ejected into the atmosphere during an eruption
93
What are primary and secondary hazards?
- primary = immediate effects of an event
- secondary hazards = indirect effects of an event that occur as a consequence of the primary hazards
94
Primary and secondary hazards of volcanoes
- primary = pyroclastic flow lava flow, volcanic bombs, volcanic gases
- secondary = lahars, forest fires, jokulhlaups, tsunamis, climate change
95
Physical factors affecting the impact of a volcanic hazard
- magnitude of eruption = greater volume of material erupted, the greater thr impact
- explosivity of eruption = more explosive eruption = more dangerous eruption products = greater loss of life
- eruption products = greater production of eruption products = greate damage to infrastructure such as building and farmland
- local physical environment = eruption products may interact w/environment in dangerous ways = e.g icy areas where volcanoes erupt may results in jokulhlaups
96
Human factors affecting the impact of volcanic hazards
-exposure = there will be worse impacts if there is a highe pop. density in affected area = more ppl experience hazards = more infrastructure damaged
- vulnerability = vulnerability (response) = well-trained + equipped emergency services reduced country’s vulnerability, but this decreases with development level
- vulnerability (management of eruption products) = not possible to manage all eruption products = related to development
- vulnerability (ability onto predict = effective volcanic monitoring program is expensive = developing countries may not have access to these
97
What country was most affected by Typhoon Haiyan? What was the date, time and location of landfall?
- country most affected = phillipines
- date = 8th November 2013
- time = 4:40am
- location = tacloban city, east coast of Philippines
98
Short term impacts of Typhoon Haiyan
- 6340 deaths
- 4.1 million made homeless
- destruction of $5.3 million worth of rice stocks
- flooding from heavy rainfall and storm surge
99
Long-term effects of typhoon Haiyan
- psychological trauma for survivors (e.g. PTSD) and grief of loss of beloved relatives
- increase in rice prices by 14% due to destruction of stocks
- forest habitat destruction due to strong winds and flooding from storm surges
100
Physical factors affecting vulnerability of Philippines to tropical cyclone hazards
- location 4.21ºN of equator smears the surrounding waters are warm = fuels à growing storm + shallow waters heat up faster + location in western Pacific Ocean pushes developing cyclones towards them by prevailing winds
- larger archipelago with a 3600km coastline = large area that can be affected by= islands mean the whole country experiences full power of the storm
- mountainous islands force people to the narrow + flatter coast = greater exposure for the whole population to storm surges
101
Economic factors affecting the vulnerability of Philippines to tropical cyclone hazards
- may ppl don’t have insurances such as home insurance that can be used to cover damage cost to property like homes = reliant on gov + international aid for home rebuilding
- GDP/capita = $3500 = lots of poverty w/ 20% of pop. below poverty line = low quality shanty housing that is easily destroyed by flooding and strong winds
- emerging country = many work in primary industries (e.g farming), which are highly vulnerable to tropical cyclones, destroying livelihoods
- e.g typhoon haiyan’s storm surge destroyed rice fields with salt water, and high winds destroyed palm groves
102
Social factors affecting the vulnerability of the Philippines to tropical cyclone hazards
- only 1.2 doctors per 1000 ppl compared to Japan’s 2.67 per 1000 = casualties from tropical cyclones may not receive high-quality care they require
- many Filipinos live in remote communities on small islands, so in aftermath of typhoons people may be isolated due to damaged infrastructure and not receive the emergency care needed
- high exposure to tropical cyclones (due to high pop. density and high pop. of 115 million = lots of ppl in harm’s way when tropical cyclones strike
103
What country was most affected by the eruption of Mount Merapi? Where and in what months in which year did it happen in?
- happened in Java, Indonesia
- year = October-November 2010
104
What margin is Java on? What type of volcano formed and what type of lava was produced?
- destructive margin = Indo-Australian plate (oceanic) subducted under Eurasian plate (continental)
- explosive eruption with acidic lava occurred as mt. Merapi is a stratovolcano
105
Name two primary and 2 secondary hazards that occurred from the mount Merapi eruption
- primary = pyroclastic flow and ash clouds
- secondary = lahars and crop failure
106
Short term impacts of mt merapi eruption
- death toll (2010) = 353
- 350,00 people displaced from homes
- food shortage from damage of crops = raised cost of living for locals due to increased food prices
- contamination of lakes and rivers from volcanic ash = reduced access to clean water + damage to aquatic ecosystems
107
Long term impacts of eruption of mount merapi
- 800 people suffered long-term psychological trauma from loss of family and livelihood
- however, the breakdown of volcanic ash over several decades will fertile use soils = high food security as high-yielding crops can be planted
- loss of people from workforce due to deaths = reduced economic output = damages economy
- final damages costs = $600 million from infrastructure, buildings and homes loss
108
Reasons people live near mount merapi
- fertil soil due to breakdown of volcanic ash from previous eruptions allows farmers to grow high-yield crops = subsistence farming and/or selling for profit = high food security as
- poverty forces poorest members of society to live in marginal areas rejected by other ppl due to danger from volcanoes + struggle to elevate due to poverty
- many Javans believe mount merapi is a sacred place for spiritual wellbeing and refuse to leave, and may people died because of this
- Indonesia’s well-developed volcano monitoring programme has successfully predicted many eruptions = people have confidence to live In dangerous locations as there believe risk is well-managed
109
Social factors affecting the vulnerability of Indonesia to volcanic hazards
- high population density = Java population is 139 million with population. density of 940/kmsq = increased exposure to hazards
- cultural reasons = many believe merapi is sacred and choose to live near to to strengthen spiritual wellbeing = make them more vulnerable as they refuse to leave
110
Economic factors affecting the vulnerability of Indonesia to volcanic hazards
- emerging country
- well-developed volcanic monitoring programme that has successfully evacuated 350,000 people
- however 10% of pop live beneath poverty line = forced to live on marginal land near to volcanoes = more vulnerable
- only 0.43 doctors/1000ppl and 1 hospital bed/1000 ppl = emergency care may be limited
111
Physical factors affecting the vulnerability of Indonesia to volcanic hazards
- sits on destructive ring of fire = high frequency of volcanic eruptions = greater risk to ppl + infrastructure = more active volcanoes than anywhere lease on earth
- magnitude of hazards = ring of fire = acidic lava + violent eruption = fast moving hazards such as pyroclastic flow is common = more deadly and dangerous than effusive eruptions that occur on constructive margins
