Volcanoes Flashcards
(106 cards)
1
Q
What is the process that leads to volcanic eruptions?
A
As tectonic plates move, pressure builds and hot magma and gases push up from the mantle to the earth’s crust and erupt.
2
Q
What is magma called when it reaches the earth’s surface?
A
Lava
3
Q
What are lava flows?
A
Streams of lava that have erupted from a volcano onto the earth’s surface.
4
Q
What is the maximum temperature lava flows can reach?
A
Up to 1170°C
5
Q
Why are lava flows generally not a threat to humans?
A
They move so slowly that people can easily get out of the way.
6
Q
What are pyroclastic flows?
A
A mixture of dense hot rock, lava, ash, and gases ejected from a volcano, moving very quickly across the earth’s surface.
7
Q
How do pyroclastic flows compare to lava flows in terms of danger?
A
They are far more dangerous due to their speed.
8
Q
What is the temperature range and speed of pyroclastic flows?
A
Extremely hot (up to [temperature not specified]) and travel at [speed not specified] per hour.
9
Q
What is tephra?
A
Pieces of volcanic rock and ash that blast into the air during volcanic eruptions.
10
Q
Where do larger pieces of tephra tend to fall during eruptions?
A
Near the volcano, where they can cause injury or death.
11
Q
How far can smaller pieces of ash travel from a volcanic eruption?
A
Thousands of kilometers.
12
Q
What are some effects of ash falls?
A
- Covers everything
- Causes poor visibility
- Creates slippery roads
- May cause roofs to collapse
- Can clog engines and stop them from working.
13
Q
A
14
Q
What gases are released during a volcanic eruption?
A
Water vapour (80%), carbon dioxide, and sulphur dioxide
These gases are dissolved in magma and are released into the atmosphere during eruptions.
15
Q
How far can volcanic gases travel in the air?
A
Thousands of kilometers
Volcanic gases can disperse over vast distances once they are released into the atmosphere.
16
Q
What are lahars?
A
Masses of rock, mud, and water that travel quickly down the sides of a volcano
Lahars can vary in size and speed, with the largest being hundreds of meters wide.
17
Q
What can cause lahars to occur?
A
Quickly melting snow and ice from an eruption or heavy rainfall eroding loose rock and soil
These conditions can lead to lahars surging downslope.
18
Q
What is a jokulhlaup?
A
A heavy and sudden flood caused by the melting of snow and ice in a glacier during a volcanic eruption
Also known as glacial outburst floods.
19
Q
Why are jokulhlaups considered dangerous?
A
They suddenly release large amounts of water, rock, gravel, and ice
This can catch people unaware and flood or damage land and structures.
20
Q
Fill in the blank: Lahars can flow at tens of _______.
A
meters per second
This indicates the speed at which lahars can travel.
21
Q
True or False: Volcanic gases primarily consist of nitrogen and oxygen.
A
False
The primary components of volcanic gases are water vapour, carbon dioxide, and sulphur dioxide.
22
Q
A
23
Q
What are hot spots in relation to volcanoes?
A
Volcanoes that form in the middle of a tectonic plate where plumes of hot magma rise upwards and erupt on the sea floor.
24
Q
What happens to a volcano when a tectonic plate moves over a hot spot?
A
The volcano is carried away with the tectonic plate, and a new volcano forms.
25
What geological feature can be created by hot spots over time?
A chain of volcanic islands.
26
Which volcanic island chain is an example of a hot spot?
Hawaiian Islands.
27
What is Montserrat?
An island in the Caribbean Sea that is part of an island arc formed by the subduction of the Atlantic plate beneath the Caribbean plate.
28
What type of rock predominantly makes up Montserrat?
Volcanic rock.
29
When did the Soufrière Hills volcano begin to erupt?
On 18 July 1995.
30
What significant event occurred as a result of the Soufrière Hills volcano eruptions?
Eruptions produced huge clouds of ash and continued for over five years.
31
What were the impacts of the volcanic eruptions on the population of Montserrat?
Dozens of people lost their lives, and more than 7000 emigrated.
32
What percentage of Montserrat's original residents emigrated due to the eruptions?
Over half of the 11,000 original residents.
33
What happened to the capital city of Montserrat, Plymouth?
It was destroyed, which contained all main services like hospitals and government offices.
34
What percentage of houses were destroyed in Montserrat due to the eruptions?
2/3rds of houses.
35
What percentage of infrastructure was destroyed in Montserrat?
3/4ths of infrastructure.
36
What economic impact did the volcanic eruptions have on Montserrat?
Unemployment rose as the island's tourist industry collapsed.
37
How did the volcanic activity affect agriculture on Montserrat?
A lot of farmland was destroyed or abandoned, severely affecting agriculture.
38
What phenomenon occurred as a result of the eruption-related emigration?
Brain drain.
39
What is the Volcanic Explosivity Index (VEI)?
A scale used to describe and compare the size or magnitude of volcanic eruptions.
40
What is the range of the Volcanic Explosivity Index?
From 0 (non-explosive) to 8 (extremely explosive).
41
What are the factors used by the VEI to assign a number?
* The amount and height of the volcanic material ejected
* How long the eruption lasted
* Qualitative descriptive terms (e.g., gentle, explosive)
42
What technologies can scientists use to predict volcanic eruptions?
GPS and satellite-based radar.
43
What are signs that a volcano might erupt?
* Small earthquakes (EQs) caused by rising magma
* Changes to the surface of the volcano
* Changes to the tilt of the volcano
44
True or False: The predictions of volcanic eruptions are 100% accurate.
False.
45
Fill in the blank: The VEI uses _____ factors to assign a number on the index.
[seven]
46
What event caused widespread flight cancellations in 2010?
Eyjafjallajokull Iceland volcanic eruption
## Footnote
The eruption created a spreading ash cloud that threatened aircraft engines.
47
How many commercial flights were cancelled worldwide due to the Eyjafjallajokull eruption?
100,000 commercial flights cancelled worldwide
## Footnote
This significant disruption affected air travel across Europe and beyond.
48
How many passengers were stranded or unable to board flights due to the eruption?
Over 10 million passengers
## Footnote
Passengers were either traveling to or from Europe.
49
What was the estimated revenue loss for airlines due to the Eyjafjallajokull eruption?
US$1.7 billion in revenue lost by airlines
## Footnote
This loss was a direct consequence of flight cancellations.
50
By what percentage was global airline capacity reduced due to the eruption?
30% of global airline capacity was cut
## Footnote
European capacity was reduced by 75%.
51
What was the estimated economic loss for the European economy due to the eyjaf eruption?
US$5 billion
## Footnote
This figure reflects the broader economic impact across Europe.
52
What percentage of Kenya's economy is based on the export of green vegetables and flowers?
20% of Kenya's economy
## Footnote
These exports are mainly directed towards the European market.
53
What was the daily cost to Kenyan businesses due to the cancellation of flights?
US$1.3 million a day
## Footnote
Businesses were forced to dump tonnes of fresh produce.
54
Fill in the blank: The Eyjafjallajokull eruption in 2010 caused flights over large parts of Europe to be cancelled for a week due to a _______.
spreading ash cloud
## Footnote
The ash cloud posed a threat to aircraft engines.
55
What are Divergent Boundaries?
Locations where two tectonic plates move apart, typically found in oceanic ridges like the Mid-Atlantic Ridge
## Footnote
Divergent boundaries are also known as constructive plate boundaries.
56
What type of lava is typically erupted at divergent boundaries?
Basaltic lava
## Footnote
Basaltic lava has a low viscosity, meaning it is fluid and can flow easily.
57
What is the eruption style at divergent boundaries?
Generally non-explosive (effusive)
## Footnote
The low viscosity of basaltic lava allows gas bubbles to escape easily, reducing the likelihood of violent explosions.
58
What type of volcanic landforms are created at divergent boundaries?
Shield volcanoes or basaltic plateaus
## Footnote
The lava spreads out over large areas, creating broad, gently sloping mountains.
59
What are the potential volcanic hazards associated with divergent boundaries?
Risks to infrastructure, formation of new oceanic crust, alteration of marine ecosystems
## Footnote
While eruptions are not usually explosive, they can still pose significant risks, especially if they occur near populated areas.
60
True or False: Eruptions at divergent boundaries are typically explosive.
False
## Footnote
Eruptions tend to produce relatively gentle lava flows due to the fluid nature of basaltic lava.
61
What occurs at convergent boundaries?
Two tectonic plates move towards each other, forming subduction zones.
62
What happens to one plate at a convergent boundary?
One plate is forced beneath another into the mantle (subduction).
63
Give an example of a convergent boundary.
The Pacific Ring of Fire, where the Pacific Plate is subducted beneath surrounding plates.
64
What type of lava is typical at convergent boundaries?
Andesitic or rhyolitic lava.
65
Why is andesitic lava more prone to trapping gases?
It has a higher viscosity than basaltic lava.
66
What is the eruption style at convergent boundaries?
Eruptions tend to be explosive.
67
Why do eruptions at convergent boundaries often lead to violent explosions?
High viscosity of the lava prevents gas from escaping easily, leading to pressure build-up.
68
What volcanic landforms are typically formed by eruptions at convergent boundaries?
Stratovolcanoes (composite volcanoes).
69
Describe the structure of stratovolcanoes.
They have steep, symmetrical slopes built up by alternating layers of lava flows and tephra.
70
What are some volcanic hazards associated with eruptions at convergent boundaries?
Pyroclastic flows, ash fallout, and lahars.
71
What are pyroclastic flows?
Fast-moving mixtures of hot gas, ash, and volcanic debris.
72
How can ash fallout from eruptions affect human activities?
It can affect air travel, contaminate water supplies, and damage crops and buildings.
73
What can cause lahars during volcanic eruptions?
When volcanic ash mixes with rainwater or melting snow.
74
What are transform boundaries?
Locations where two tectonic plates slide past each other horizontally
## Footnote
Examples include the San Andreas Fault in California.
75
What type of volcanic activity is common at transform boundaries?
Volcanic eruptions are rare
## Footnote
Main interaction is horizontal shearing rather than vertical movement.
76
What is the eruption style at transform boundaries?
Usually mild if eruptions occur
## Footnote
Due to the lack of magma generation through subduction or rifting.
77
What is the main hazard at transform boundaries?
Seismic activity (earthquakes)
## Footnote
Volcanic activity could still occasionally occur in some areas.
78
Fill in the blank: The main interaction at transform boundaries is _______.
horizontal shearing
79
True or False: Volcanic eruptions are frequent at transform boundaries.
False
80
What is the viscosity of basaltic lava?
Low viscosity
## Footnote
Basaltic lava flows easily and quickly due to its fluid consistency.
81
What is the gas content of basaltic lava compared to other types?
Lower gas content
## Footnote
This characteristic contributes to its effusive eruption style.
82
What type of eruption is associated with basaltic lava?
Effusive eruptions
## Footnote
These eruptions are non-explosive and involve lava gently pouring out.
83
What type of volcano is typically formed by basaltic lava?
Shield volcanoes
## Footnote
These volcanoes have wide, low profiles due to the gentle flow of basaltic lava.
84
What impact does basaltic lava have on volcanic landforms?
Creates expansive lava plateaus or shield volcanoes
## Footnote
The lava spreads over large areas, resulting in gentle slopes.
85
What are the volcanic hazards associated with basaltic lava eruptions?
Destruction of infrastructure, farms, and communities
## Footnote
Despite being non-explosive, lava flows can cause significant damage.
86
True or False: Basaltic lava eruptions are explosive.
False
## Footnote
Basaltic lava results in non-explosive, effusive eruptions.
87
Fill in the blank: Basaltic lava is common at _______ boundaries.
Divergent
## Footnote
This type of lava is typically found at divergent tectonic plate boundaries.
88
What type of lava is common at convergent boundaries?
Andesitic Lava
## Footnote
Andesitic lava is characterized by its moderate viscosity and higher gas content.
89
What is the viscosity of andesitic lava?
Moderate viscosity
## Footnote
It flows more slowly than basaltic lava but not as slowly as rhyolitic lava.
90
How does the gas content of andesitic lava compare to basaltic lava?
Higher gas content
## Footnote
This contributes to its explosive eruption style.
91
What is a common eruption style associated with andesitic lava?
Often explosive
## Footnote
The higher viscosity traps gas, leading to pressure build-up.
92
What volcanic landforms are typically formed by andesitic lava?
Stratovolcanoes
## Footnote
These have steep, symmetrical slopes and are composed of alternating layers of lava and pyroclastic material.
93
What are the significant volcanic hazards posed by andesitic lava?
Pyroclastic flows, ash clouds, and lava domes
## Footnote
These can threaten nearby settlements and disrupt air travel.
94
Fill in the blank: Andesitic lava is often associated with _______ eruptions due to its higher viscosity.
explosive
## Footnote
This explosive nature is due to gas trapping in the magma chamber.
95
What can ash clouds from andesitic lava eruptions disrupt?
Air travel
## Footnote
Ash clouds pose significant risks to aviation.
96
What is a potential consequence of pyroclastic flows associated with andesitic lava?
Widespread destruction
## Footnote
Pyroclastic flows can cause severe damage to surrounding areas.
97
What are the two types of lava flows mentioned?
Basaltic and andesitic lava flows
## Footnote
Basaltic lava flows are less destructive due to their slow pace, while andesitic flows can be more damaging.
98
What can lava flows destroy?
Infrastructure, homes, and crops
## Footnote
Both basaltic and andesitic lava flows have the potential to cause significant damage.
99
What are pyroclastic flows primarily associated with?
Convergent boundaries with andesitic or rhyolitic lava
## Footnote
Pyroclastic flows are fast-moving, hot clouds of gas and volcanic material.
100
What is the primary cause of fatalities in explosive eruptions?
Pyroclastic flows
## Footnote
These flows can destroy everything in their path due to their speed and temperature.
101
What are the impacts of ash fallout?
Destruction of crops, contamination of water supplies, collapse of buildings, and effects on air travel
## Footnote
Ash can blanket large areas and has notably affected air travel, as in the 2010 Eyjafjallajökull eruption.
102
What can trigger lahars during a volcanic eruption?
Heavy rainfall or melting of snow and ice
## Footnote
Lahars are mudflows composed of ash, water, and debris that can cause widespread destruction.
103
Fill in the blank: Pyroclastic flows are primarily caused by _______.
explosive eruptions
104
True or False: Basaltic lava flows are more destructive than andesitic lava flows.
False
## Footnote
Basaltic lava flows are generally less destructive due to their slower pace.
105
What can happen to buildings under the weight of ash?
Collapse
## Footnote
Ash fallout can lead to significant structural damage to buildings.
106
What are lahars composed of?
Ash, water, and debris
## Footnote
Lahars can travel quickly and cause extensive damage in valleys and river systems.
