Unit 1 Flashcards
(94 cards)
1
Q
Natural hazards
A
extreme natural processes or events which threaten human life and property
2
Q
Causes of natural hazards
A
- extreme weather conditions
- instability of land surfaces
- processes within the earth
3
Q
examples of extreme weather conditions
A
flooding, drought, tropical cyclones
4
Q
examples of instability of land surfaces
A
landslides
5
Q
examples of processes within the earth
A
earthquakes, volcanic eruptions, tsunami
6
Q
structure of the earth
A
- crust
- mantle
- core
7
Q
crust
A
- made up of solid rock
- the thinnest in terms of thickness
- temperature and density are the lowest
- some parts are thicker, forming the continents; some parts are thinner, forming the oceans
- broken into pieces called tectonic plates
8
Q
the crust is made up of ______
A
solid rock
9
Q
thinnest layer of the earth (in terms of thickness)
A
crust
10
Q
earth layer with the lowest temperature
A
crust
11
Q
earth layer with the lowest density
A
crust
12
Q
thicker parts of the crust form _____, while thinner parts form _______
A
continents, oceans
13
Q
the crust is broken into pieces called ______
A
tectonic plates
14
Q
mantle
A
- mostly made up of solid rock
- magma can also be found where solid rock melts to become molten or semi-molten
- the layer is hotter and denser than the crust
15
Q
when solid rock melts, it turns into ______
A
magma
16
Q
core
A
- made up of a combination of metals under very high temperature and pressure
- the hottest and densest part of earth
17
Q
earth layer with the highest temperature
A
core
18
Q
earth layer with the highest density
A
core
19
Q
narrow zone between two moving tectonic plates
A
plate boundary
20
Q
different tectonic plates
A
- Eurasian plate
- African plate
- Indo-Australian plate
- Pacific plate
- North American plate
- South American plate
- Antarctic plate
21
Q
examples of tectonic belts
A
- circum-pacific belt
- alpine-Himalayan belt
22
Q
traditional model of plate tectonics: movements are driven by _________
A
convection currents
23
Q
process of plate tectonics (traditional model)
A
- mantle near the core is heated and rises
- mantle near the crust cools, becomes denser and sinks back down
- mantle is heated again near the core and rises. the process (convection) repeats
- converging currents pull the plates together
- diverging currents pull the plates apart
24
Q
nowadays model of plate tectonics: movement driven by _________
A
slab pull
25
subduction
the process in which the denser plate bends and slides under the other when two plates collide
26
slab pull
the process in which the edge of the seafloor pulls the plate behind it due to its weight as it sinks into the mantle
27
process of plate tectonics (nowadays model)
- when two plates collide, the denser plate bends and slides under the other. (subduction)
- as the seafloor sinks into the mantle, it pulls the plate behind it due to its weight (slab pull). gravity plays a major role in driving plate tectonics
28
Earthquakes
the violent shaking of the earth crust
29
the ________ of an earthquake is measured on the ___________ scale
magnitude, Richter
30
In what plate boundary types do earthquakes occur
all types, but the ones at destructive & conservative plate boundaries are especially high in magnitude
31
high magnitude earthquakes create ______ damage but have ________ frequency
greater, lower
32
formation of an earthquake
1. when plates move, pressure is built up along the plate boundaries
2. the pressure becomes too large and the plates can no longer withstand
3. the plate displace and fracture suddenly
4. at the point of the fracture (focus), large amount of energy is released in all directions in the form of seismic waves
5. violent shaking of the earth's crust is resulted
33
focus
the point beneath earth's surface where rock breaks and earthquake begins
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depth of focus
the depth between the focus and the ground surface
35
epicenter
the point on the earth's surface directly above the focus
36
seismic waves
the form of waves that carry the energy released by the earthquake from the focus
37
deeper earthquakes cause _______ damage (and why)
less, because there is longer distance for the seismic waves to travel to the epicenter
38
the Himalayas is created by ____________
plate movements
39
types of plate movement
- constructive plate boundary
- destructive plate boundary
- conservative plate boundary
40
constructive plate boundary
- plates move away from each other
- melted rock (magma) rises up and cools at the plate boundary
--> creating new crust and volcanoes
41
destructive plate boundary
- plates move towards each other
- a subduction may occur
--> creating volcanoes
- crusts may buckle up
--> creating mountain folds
42
conservative plate boundary
- plates slide past each other
- no volcanoes or fold mountains are formed
43
negative effects caused by earthquakes
- people are killed and injured
- buildings and infrastructure (e.g. roads and bridges) and damaged
- power lines collapse/are damaged
- fire broke out
- strong shaking causes the dam to collapse
44
secondary hazards cause by earthquakes
- landslides
- tsunamis
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effects of earthquake details: people are killed and injured
- due to collapsing buildings
- emergency response and rescue are needed
46
effects of earthquake details: buildings and infrastructure (e.g. roads and bridges) and damaged
disrupts traffic/block roads
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effects of earthquake details: power lines collapse/are damaged
electricity is cut
--> residents experience power blackout
48
effects of earthquake details: strong shaking causes the dam to collapse
flooding may occur in the lower part of the river
49
effects of earthquake details: landslides may occur
- due to the instability of slope materials
- block roads/disrupt traffic
50
negative effects caused by volcanic eruptions
Damages
- people and livestock are killed and injured
- crops are damaged
lava flows...
- damage settlements and roads
- cause fires and burns the forest
dust and ash from volcanoes...
- lower the air quality/visibility (x air pollution)
- may jam plane engines and cause aviation hazards
51
all negative effects of natural hazards can lead to _________
economic loss
52
effects of volcanic eruptions details: people and livestock are killed and injured
buried/chokes/burnt by hot volcano ash
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effects of volcanic eruptions details: lava flows damage settlements and roads
economic loss/loss of lives and property
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effects of volcanic eruptions details: crops are damaged
- farmers will lose their income
- fruits and vegetables may become more expensive during that period of time
- may create a food shortage
55
effects of volcanic eruptions details: dust and ash from volcanoes lower the air quality/visibility (x air pollution)
- disrupt traffic
- hazards to health
56
effects of volcanic eruptions details: lava flows cause fires and burns the forest
- kill trees and animals
- may threaten people living further away
57
effects of volcanic eruptions details: dust and ash clouds may jam plane engines and cause aviation hazards
flights are delayed
58
volcanoes are found at
tectonically unstable regions (at constructive and destructive plate boundaries)
-> cracks & magma chambers are present beneath the earth's surface
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when does a volcanic eruption occur
when the pressure in the magma chamber gets too great
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what happens during a volcanic eruption
normal: lava and gases are erupted
more explosive: large amount of ash and rock blocks are also erupted
61
when magma rises to the surface, we call it ____. Layers of ash and ______ _____________ to form volcanoes
lava, lava, cool and solidify
62
features of a volcano
- vent
- crater
- magma chamber
- volcanic ash and gas
- lava
- volcanic blocks
- layers of solidified ash and lava
63
key factors affecting the degree of damage caused by earthquakes
- nature of the hazard
- demographic (population) characteristic of the area
- development of the country/community
- government efficiency
64
nature of the hazard four aspects
- magnitude
- depth of focus
- time of occurrence
- frequency and regularity of the hazards
65
factors affecting degree of damage of earthquake: magnitude
the higher the magnitude, the greater the damage
66
factors affecting degree of damage of earthquake: depth of focus
Shallower earthquakes tend to create greater damage
67
factors affecting degree of damage of earthquake: time of occurrence
If earthquake occurs in midnight, higher death toll would be resulted
68
factors affecting degree of damage of earthquake: frequency and regularity of the hazards
People are generally more aware of hazards that occur frequently and regularly, and hence, more prepared for the potential dangers
69
two aspects of demographic characteristics (population) of the area
- population density
- age of the population
70
factors affecting degree of damage of earthquake: population density
the higher the population density at the area where the hazard strikes, the greater the damage
71
factors affecting degree of damage of earthquake: age of the population
School children and elderly might need assistance in escaping the area
72
two aspects of development of the country/community
- level of economic development
- level of education
73
factors affecting degree of damage of earthquake: level of economic development
affects the amount of funding for preventive measures and emergency responses
74
factors affecting degree of damage of earthquake: level of education
affects the awareness, as well as the amount of medical personnel, etc
75
two aspects of government efficiency
- government effectiveness
- law enforcement
76
factors affecting degree of damage of earthquake: government effectiveness
- corruption often leads to the diversion of funding
- ineffective governments are slow in coordinating rescue efforts and managing relief supplies
77
factors affecting degree of damage of earthquake: law enforcement
if building codes are not in place or enforced, greater damage would be resulted
78
preparing for & responding to natural hazards -- preventative measures
- monitoring and warning system
- building design
- education
- land use zoning
79
hazard preventative measures: monitoring and warning system
- scientists detect seismic activities with the use of seismometers
- the government will issue an early warning when an earthquake/volcanic eruption is likely to occur
80
monitoring and warning system function
to allow time for people to take actions to prepare for the hazard e.g. evacuation
81
hazard preventative measures: building design
in earthquake-prone regions , all buildings, roads and bridges should have earthquake proof/shake proof design to withstand the vigorous shaking of land
82
building design function
to ensure the safety of the area as most deaths are caused by the collapse of buildings
83
hazard preventative measures: education
- the government educates the public on how to respond to earthquakes
- e.g. earthquake drills should be held
84
education function
- people are more likely to save themselves -> improve the efficiency of rescue
- to get familiar with the evacuation route
85
hazard preventative measures: land use zoning
- high-risk areas can be used for recreation or greenbelt only
- restrict the building heights and densities in the areas
- dangerous factories/power plants should not be built in hazard prone areas
- plan temporary shelters in schools, sports ground and park for emergency evacuation
86
land use zoning function
- to reduce the damage of earthquakes
- to reduce the number of vulnerable population in the most hazard-prone regions
87
preparing for & responding to natural hazards -- remedial measures
- emergency assistance
- rehabilitation
88
hazard preventative measures: emergency assistance
- efficient rescue and emergency medical assistance are essential
- temporary shelters and emergency supplies such as water, food and blankets will also be provided
89
emergency assistance function
to ensure that the basic needs of the survivors are met
90
hazard preventative measures: rehabilitation
- the government restores the damaged buildings and infrastructure
- counselling service will also be provided to survivors
91
rehabilitation function
to ensure that victims can go home and live a normal life again
92
why do people still live in hazard prone areas -- benefits of a place for living
- volcanoes are tourist attractions
- gentle slopes at the bottom of volcanoes are suitable for farming and settlement
- volcanic ash make the soil fertile
- useful minerals (e.g. gold) are found in volcanic areas
- steam and heat in the volcanic areas provide geothermal power
- many big cities which are affected by earthquakes (e.g. tokyo) have very high standards for living
--> provide a lot of jobs and economic opportunities
93
why do people still live in hazard prone areas -- other reasons
- Optimistic views of people on hazards.
Sometimes they underestimate the risks of
natural hazards.
- Some people believe that their governments have enough mone and advanced
technology to cope with the hazards.
- Some people prefer to stay because of family
and social ties.
- Some people are very used to their own
lifestyle and culture of
the home country. They might be afraid that
they would not be able to adapt to the new environment.
- People have no choice
because of poverty. The migration policies in other countries may also be very strict
94
why do people still live in hazard prone areas
people think that the benefits outweigh the costs
