Earthquakes And Volcanoes Flashcards
1
Q
How does a volcano form?
A
A volcano forms when magma erupts onto the Earth’s surface as lava through a vent in the Earth’s crust.
2
Q
What is lava?
A
When magma erupts onto the surface, it is called lava.
3
Q
How is the magnitude of a volcanic eruption measured?
A
The magnitude of a volcanic eruption is measured on the Volcanic Explosivity Index (VEI).
4
Q
What is the highest recorded VEI?
A
The highest in recorded human history was an 8 (Tambora 1815).
5
Q
What are composite volcanoes?
A
Composite volcanoes, also known as strato-volcanoes, have steep sides, sticky lava, more explosive eruptions, and alternating layers of ash and lava.
6
Q
Where do composite volcanoes tend to form?
A
They tend to form on convergent (destructive) plate boundaries.
7
Q
What are shield volcanoes?
A
Shield volcanoes have gently sloping sides, runny lava, less explosive eruptions, and frequent eruptions.
8
Q
Where do shield volcanoes tend to form?
A
They tend to form on divergent (constructive) plate boundaries or hot spots.
9
Q
What are the three types of volcanoes based on activity?
A
Volcanoes may be active, dormant, or extinct.
10
Q
What defines an active volcano?
A
An active volcano has recently erupted and is likely to erupt again.
11
Q
What defines a dormant volcano?
A
A dormant volcano has not erupted for many years but there is evidence of a magma reservoir.
12
Q
What defines an extinct volcano?
A
An extinct volcano shows no evidence of eruption in historic times and there is no evidence of a magma reservoir.
13
Q
What are some features of volcanic eruptions?
A
Eruptions may include lava, ash, pyroclastic flow, lahars, earthquakes, and volcanic bombs.
14
Q
What is ash in volcanic eruptions?
A
Ash is pulverised solid lava which measures less than 2 mm in diameter and can travel thousands of kilometres.
15
Q
What is pyroclastic flow?
A
Pyroclastic flow is fast-moving, very hot clouds of poisonous gases mixed with ash, averaging speeds of about 100 km/h but can move at up to 700 km/h.
16
Q
What are lahars?
A
Lahars occur when volcanoes erupt and snow and ice on the peak melt, creating fast-moving mudflows.
17
Q
What causes earthquakes?
A
Earthquakes are caused by magma rising to the surface through the vents in the volcano, increasing pressure on the Earth’s crust.
18
Q
What are volcanic bombs?
A
Volcanic bombs are fragments of molten rock ejected from the volcano, ranging from 60 mm to 5 m in diameter.
19
Q
What is an earthquake?
A
An earthquake is the sudden, violent shaking of the ground.
20
Q
What causes earthquakes?
A
Earthquakes are the result of pressure building when tectonic plates move.
21
Q
What is the epicentre of an earthquake?
A
The epicentre is the point on the Earth’s surface directly above the focus.
22
Q
What is the focus of an earthquake?
A
The focus is the point at which the earthquake starts below the Earth’s surface.
23
Q
How is the magnitude of an earthquake measured?
A
The magnitude is measured on the Moment Magnitude Scale, which replaced the Richter scale.
24
Q
How is earthquake damage measured?
A
The damage caused by earthquakes is measured on the Mercalli Scale.
25
Where do earthquakes mostly occur?
Earthquakes can occur anywhere but mostly occur at or near plate boundaries.
26
What types of plate boundaries do earthquakes happen at?
Earthquakes happen at constructive (divergent), destructive (convergent), collision, and conservative (transform) plate boundaries.
27
What is the sequence of an earthquake?
As tectonic plates move, they can get stuck, pressure builds, and eventually the plates jolt free, releasing energy.
28
What can cause earthquakes aside from natural processes?
Earthquakes can also happen as a result of human activity such as drilling into the crust or mining.
29
Volcano
30
Composite (Strato Volcanoes)
31
Shield volcano
32
Where do most earthquakes occur?
Most earthquakes (approximately 90%) occur around the rim of the Pacific Ocean.
## Footnote
This zone is called the 'Ring of Fire'.
33
At what types of plate boundaries do most volcanoes occur?
Most volcanoes occur at divergent (constructive) and convergent (destructive) plate boundaries.
34
Where are the majority of active volcanoes located?
Approximately 75% of active volcanoes are located around the Pacific 'Ring of Fire'.
35
What are hotspots in relation to volcanoes?
Hotspots are areas away from plate boundaries where volcanoes occur, consisting of plumes/columns of magma that escape through the Earth's crust.
36
Structure of the earth
37
What are the two types of Earth's crust?
Continental crust and oceanic crust.
38
Describe continental crust.
Continental crust is thick (25–90 km), old, and not as dense as oceanic crust.
39
Describe oceanic crust.
Oceanic crust is thinner (5-10 km), heavier, and denser than continental crust.
40
What happens to oceanic crust due to plate movement?
Oceanic crust is continually being created and destroyed; it subducts under the continental crust because it is denser.
41
What is the relationship between the Earth's crust and tectonic plates?
The crust is broken into many tectonic plates.
42
What moves on top of the semi-molten mantle?
The tectonic plates move on top of the semi-molten mantle below.
43
What causes the movement of tectonic plates?
The movement of the plates is in part due to the convection currents within the mantle.
44
What is a plate boundary?
A plate boundary or margin is where two plates meet.
45
Where do volcanic eruptions and earthquakes commonly occur?
Volcanic eruptions and earthquakes most commonly occur at or near plate boundaries.
46
What are the four main types of plate boundaries?
The four main types of plate boundaries are: Divergent (constructive), Convergent (destructive), Collision, and Transform (conservative).
47
What happens at a divergent (constructive) plate boundary?
At a divergent boundary, the plates are moving apart.
## Footnote
The Mid-Atlantic Ridge is an example of a divergent plate boundary.
48
What occurs at a convergent (destructive) plate boundary?
At a convergent (destructive) plate boundary, the plates are moving towards each other.
## Footnote
The denser oceanic plate subducts under the lighter continental plate.
49
What is a collision boundary?
At a collision boundary, two plates of similar density move towards each other, pushing the land upwards to form fold mountains.
50
What happens at a transform (conservative) boundary?
At a transform (conservative) boundary, the plates move past each other in opposite directions or in the same direction at different speeds.
51
Where do volcanoes occur?
Volcanoes occur at divergent (constructive), convergent (destructive) plate boundaries and hot spots.
52
What characterizes volcanic eruptions at divergent plate boundaries?
At divergent plate boundaries, the lava tends to be runny, and eruptions are less explosive, often forming shield volcanoes.
53
What occurs at destructive plate boundaries?
At destructive (convergent) boundaries, the heavier oceanic plate subducts under the lighter continental plate, causing explosive eruptions that form composite or stratovolcanoes.
54
What happens at hot spots?
At a hot spot, the tectonic plate passes over a plume of magma, forming a line of islands as the plate moves over the magma plume.
## Footnote
An example is the Hawaiian Islands.
55
Where do earthquakes mostly occur?
Earthquakes mostly occur at or near plate boundaries.
56
How do earthquakes vary at different plate boundaries?
At divergent (constructive) plate boundaries, earthquakes tend to be weaker, while at convergent (destructive), collision, and transform (conservative) boundaries, they tend to be stronger.
57
Convergent (destructive)
58
Divergent (constructive)
59
Collision boundary
60
Conservative boundary
61
Earthquake
62
What are the two categories of hazards from earthquakes and volcanic eruptions?
Primary hazards and Secondary hazards.
63
What are primary hazards?
These are a direct result of the earthquake or eruption.
64
What are secondary hazards?
These occur as a result of the primary effects.
65
List primary hazards of earthquakes.
Ground Shaking, Surface rupture, Liquefaction, Landslides, Tsunami.
66
List primary hazards of volcanic eruptions.
Pyroclastic flow, Lava flow, Volcanic Bombs, Lahars (mudflow).
67
What are some secondary hazards of earthquakes?
Direct ashfall, Landslides, Tsunami, Acid rain, Ash fallout from the atmosphere.
68
What factors affect the impacts of earthquakes and volcanic eruptions?
Both human and physical factors.
69
What human factors affect earthquake impacts?
Building construction and design, Building density, Population density, Preparation.
70
How does building construction affect earthquake impacts?
Poorly constructed buildings are more likely to collapse.
71
How does population density affect earthquake impacts?
Higher density means more people are likely to be injured or killed.
72
What physical factors affect earthquake impacts?
Magnitude, Geology, Distance from the epicentre, Depth.
73
How does magnitude affect earthquake impacts?
Usually, the higher the magnitude, the greater the impact.
74
What human factors affect volcanic impacts?
Proximity of population, Planning and preparation.
75
How does proximity of population affect volcanic impacts?
The closer people are to the volcano, the more likely they are to be affected.
76
What physical factors affect volcanic impacts?
Magnitude, Type of volcano, Amount of ash ejected into the atmosphere.
77
What are some effects of earthquakes and volcanic eruptions?
Loss of life and injury, Collapse or destruction of buildings, Damage to transport network.
78
What are the economic impacts of earthquakes and volcanic eruptions?
Loss of jobs and businesses, Loss of crops.
79
What environmental impacts can result from earthquakes and volcanic eruptions?
Damage to the environment, Loss of vegetation and habitat, Effects on climate.
80
Why are airports closed during volcanic eruptions?
It is dangerous for jet planes to fly through ash clouds due to possible engine failure.
81
How many people are estimated to live in seismically active areas by 2025?
It is estimated that 600 million people will live in seismically active areas by 2025.
82
What are some hazards associated with living in seismically active areas?
There are many hazards associated with living in areas vulnerable to earthquakes and volcanic eruptions.
83
What is one opportunity associated with living near volcanoes?
Fertile soil is one opportunity associated with living near volcanoes.
84
How does volcanic ash contribute to agriculture?
The ash and cooled lava contain many minerals, which lead to high crop yields.
85
What economic opportunity does tourism provide in volcanic areas?
Many people want to visit areas where there are active volcanoes; this increases the number of jobs available.
86
What can be mined and sold near volcanoes?
Minerals and precious stones can be mined and sold, providing work for local people.
87
How can geothermal energy be harnessed in volcanic areas?
As the magma is closer to the surface, the heat can be used to generate geothermal energy.
88
What happens to land once lava and ash have cooled?
Once the lava and ash have cooled, new land is formed.
89
What is a benefit of building regulations in earthquake zones?
Areas have stricter building regulations to ensure that construction can withstand seismic activity.
90
How does community preparedness benefit earthquake-prone areas?
Residents in earthquake-prone areas tend to be more prepared for natural disasters, resulting in a more resilient community.
91
What attracts researchers to earthquake-prone areas?
Earthquake-prone areas attract researchers and engineers focused on developing technology for earthquake prediction and building strength.
92
What natural feature can make earthquake-prone areas attractive to live in?
Some people find the scenery, geological formations, and outdoor leisure opportunities attractive.
93
Why might some people have little choice but to live in earthquake zones?
Some people have little choice but to live in earthquake zones due to limited money, despite the risks.
94
How many people are estimated to live in seismically active areas by 2025?
It is estimated that 600 million people will live in seismically active areas by 2025.
95
What are some hazards associated with living in seismically active areas?
There are many hazards associated with living in areas vulnerable to earthquakes and volcanic eruptions.
96
What is one opportunity associated with living near volcanoes?
Fertile soil is one opportunity associated with living near volcanoes.
97
How does volcanic ash contribute to agriculture?
The ash and cooled lava contain many minerals, which lead to high crop yields.
98
What economic opportunity does tourism provide in volcanic areas?
Many people want to visit areas where there are active volcanoes; this increases the number of jobs available.
99
What can be mined and sold near volcanoes?
Minerals and precious stones can be mined and sold, providing work for local people.
100
How can geothermal energy be harnessed in volcanic areas?
As the magma is closer to the surface, the heat can be used to generate geothermal energy.
101
What happens to land once lava and ash have cooled?
Once the lava and ash have cooled, new land is formed.
102
What is a benefit of building regulations in earthquake zones?
Areas have stricter building regulations to ensure that construction can withstand seismic activity.
103
How does community preparedness benefit earthquake-prone areas?
Residents in earthquake-prone areas tend to be more prepared for natural disasters, resulting in a more resilient community.
104
What attracts researchers to earthquake-prone areas?
Earthquake-prone areas attract researchers and engineers focused on developing technology for earthquake prediction and building strength.
105
What natural feature can make earthquake-prone areas attractive to live in?
Some people find the scenery, geological formations, and outdoor leisure opportunities attractive.
106
Why might some people have little choice but to live in earthquake zones?
Some people have little choice but to live in earthquake zones due to limited money, despite the risks.
107
What are the two types of responses to earthquakes and volcanic eruptions?
Short-term responses occur immediately after an event, while long-term responses aim to reduce the impact of future hazardous events.
108
What are examples of short-term responses to earthquakes?
Aid and disaster relief.
109
What are long-term responses to earthquakes?
Long-term responses include risk assessments and hazard mapping.
110
Is accurate prediction of earthquakes currently possible?
No, accurate prediction is not currently possible, but monitoring is.
111
What methods are used for monitoring earthquakes?
Methods include tiltmeters, clusters of small earthquakes, changes in radon gas emissions, changes in animal behavior, and remote sensing of ground movement using satellites.
112
What building features are required in earthquake-resistant designs?
Features include shutters on windows, cross-bracing of steel frames, flexible building materials, deep foundations, swaying frames, rubber shock absorbers, reinforced walls, shatterproof glass, fire-resistant materials, and automatic cut-off for gas/electricity.
113
What is the purpose of earthquake drills?
Earthquake drills help people prepare for what to do in an earthquake to protect themselves.
114
How does education contribute to earthquake safety?
Education about home preparation reduces the likelihood of injuries from falling objects and furniture.
115
What is the role of remote sensing in volcanic and earthquake planning?
Remote sensing provides data about changes in ground movement.
116
What does Geographic Information Systems (GIS) provide?
GIS provides layers of data such as vulnerable areas, land use, and infrastructure.
117
How is GIS data used in land use planning?
GIS data assists with planning to avoid building valuable services in high-risk areas.
118
What is the purpose of land use planning in relation to earthquakes?
Land use planning maps areas most at risk from earthquakes and locates densely populated housing away from high-risk areas.
119
What are the two types of responses to earthquakes and volcanic eruptions?
Short-term responses occur immediately after an event, while long-term responses aim to reduce the impact of future hazardous events.
120
What are examples of short-term responses to earthquakes?
Aid and disaster relief.
121
What are long-term responses to earthquakes?
Long-term responses include risk assessments and hazard mapping.
122
Is accurate prediction of earthquakes currently possible?
No, accurate prediction is not currently possible, but monitoring is.
123
What methods are used for monitoring earthquakes?
Methods include tiltmeters, clusters of small earthquakes, changes in radon gas emissions, changes in animal behavior, and remote sensing of ground movement using satellites.
124
What building features are required in earthquake-resistant designs?
Features include shutters on windows, cross-bracing of steel frames, flexible building materials, deep foundations, swaying frames, rubber shock absorbers, reinforced walls, shatterproof glass, fire-resistant materials, and automatic cut-off for gas/electricity.
125
What is the purpose of earthquake drills?
Earthquake drills help people prepare for what to do in an earthquake to protect themselves.
126
How does education contribute to earthquake safety?
Education about home preparation reduces the likelihood of injuries from falling objects and furniture.
127
What is the role of remote sensing in volcanic and earthquake planning?
Remote sensing provides data about changes in ground movement.
128
What does Geographic Information Systems (GIS) provide?
GIS provides layers of data such as vulnerable areas, land use, and infrastructure.
129
How is GIS data used in land use planning?
GIS data assists with planning to avoid building valuable services in high-risk areas.
130
What is the purpose of land use planning in relation to earthquakes?
Land use planning maps areas most at risk from earthquakes and locates densely populated housing away from high-risk areas.
