Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Tectonics > Unit 2 > Flashcards

Unit 2 Flashcards

(94 cards)

Start Studying
1
Q

What are the three main types of volcanoes?

A
  • Shield
  • Composite
  • Cinder
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the characteristics of shield volcanoes?

A

shallow sloping mountains
- formed by low viscosity lava - fast and far flowing
- form in layers due to frequent effusive eruptions
- form on divergent plate boundary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the characteristics of a composite volcanoes?

A

steep sided
- experience more explosive eruptions, form with high viscosity lava
- tall and cone shaped
- form on a divergent plate boundary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the characteristics of a cinder volcano?

A

ash and cinder build up in a cylindrical cone of relatively small size, they are highly permeable
-form in layers of ash and lava
-can be explosive, but not as explosive as composite volcanoes
- forms on destructive plate boundary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is meant by high viscosity?

A

a substance such as honey has high viscosity as the texture is thick, not very runny

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is meant by low viscosity?

A

A substance such as water is low as its fluid and runny

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What makes lava viscous?

A

when it contains silica/silica oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does an explosive eruption occur?

A
  • involves high viscosity lava
  • causes gasses that are trapped to accumulate, which builds up the pressure
  • this causes huge amounts of pressure to be released at once
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does an effusive eruption occur?

A
  • involves low viscosity lava (flows easily)
  • ‘gentle’ eruptions, easily flow down the volcano
  • creates gently sloping volcanoes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a phreatomagmatic eruption?

A

a type of explosive eruption that results from the magma erupting through water i.e. glaciers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is meant by viscosity?

A

the ability to resist flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What type of eruption occurs when the magma has a high viscosity?

A

explosive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What type of eruption occurs when the magma has low viscosity?

A

effusive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What substance determines the viscosity of the lava?

A

silicon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

If there is little amount of silicon in the lava, how viscous is it?

A

low viscosity = dissolving gases can escape to the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

If there is high amounts of silicon in the lava, how viscous is it?

A

high viscosity = traps gases, pressure builds and leads to explosive eruption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

If the magma contains more gas, what type of eruption will occur, compared to if the magma contains less gass?

A

more gas = more violent eruption
less gas = effusive eruption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is meant by the VEI scale, and what does it measure?

A

Volcanic Explosivity Index

= logarithmic scale, which ranges between 0 - 8, each step in the scale represents an increase in explosivity by a factor of 10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is meant by magnitude?

A

the greater the VEI of a volcano, the more explosive = more severe impacts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is meant by the frequency of volcanoes?

A

once a large volcanic eruption has occurred it is unlikely that another one will occur soon after in the same location

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is meant by the predictability of a volcano?

A

possible to monitor and predict how severe the event is likely to be, people are able to evacuate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is meant by the aerial extent of a volcano?

A

damage relating to volcanoes in terms of how far the impacts are felt depending on what type of eruption it is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is meant by the speed of onset of a volcano?

A

effective volcano monitoring reveals that volcanoes give many clues that they are becoming active before an eruption actually occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is meant by the duration of a volcano?

A

the duration of the event does not necessarily correlate with the severity of the impacts, effusive eruptions can last for weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are three examples of local hazards?
- Pyroclastic flow - Lava flow - Volcanic landslides
26
What are two examples of (water based) regional hazards?
- Lahar - Jokulhlaups
27
What are two examples of (airborne) international hazards?
- Toxic gases - Ash falls
28
What is the definition of ash fall?
deposition of fine volcanic ash onto the ground after an explosive eruption
29
What are the hazards and causes of ash fall?
- structural damage from the ashfall - ash can contaminate water supplies - power outages and crop/vegetation damage - clean up challenges - travel disruptions - large regional cooling
30
What is an example of a volcanic eruption with significant ashfall?
E-15 (Eyjafjallajokull) Iceland, 2010
31
What was the date of the E-15 eruption in Iceland?
March 20th to June 23rd 2010
32
What was the magnitude of E-15?
VEI 3
33
What was the tectonic setting of E -15?
Constructive/divergent Mid Atlantic ridge plate margin
34
What where the social impacts of E-15?
0 deaths 800 people evacuated
35
What where the local impacts of E-15?
- Areas were flooded because of the glacier melt water which lay above the volcano - Agricultural land was damaged, farms heavily hit by heavy ashfall - ashfall poisoned animals and water sources - roads destroyed - people asked to stay indoors
36
What where the international impacts of E-15?
- Travel was severely disrupted as 100,000 flights were cancelled between 14 and 21 April 2010 - businesses lost trade - air operators lost $1.1 billion through cancellations - people couldn't work, they were stranded - perishable foods and goods such as flowers from Kenya were wasted as they couldn't be transported
37
What is the definition of pyroclastic flow?
hot avalanches of rock, ash and gas that travel down volcano slopes at high speeds
38
What are the hazards and causes of pyroclastic flows?
surges can bury, burn and destroy things upon impact contain lots of gases that con asphyxiate people (choke) surges are very fast
39
What is the example of a volcanic eruption with a pyroclastic flow?
Montserrat, 1995
40
When was the Montserrat eruption?
July 1995 and 1997
41
What magnitude was the Montserrat eruption?
VEI 3
42
What was the tectonic setting of the Montserrat eruption?
Subduction zone
43
What were the social impacts of Montserrat?
19 people died from the pyroclastic flows
44
What where the short term responses of the Montserrat eruption?
- evacuation to UK and neighboring islands - abandonment of the capital city - the British gov gave £2400 to each person for compensation and redevelopment - Unemployment rose due to the collapse of the tourist industry
45
What where the long term benefits of the Montserrat eruption?
- an exclusion zone set up in the volcanic region - a volcanic observatory was built (MVO) - new roads and a new airport built - Services in the north of the island were expanded - presence of volcano = growth of tourism
46
What is the definition of a lahar?
are hot mixtures of volcanic materials interacting with water, ice and snow, travel rapidly
47
What are the hazards and causes of a lahar?
- pose a threat to people and infrastructure - natural dam failure - travel very fast and are severely damaging
48
What is an example of an eruption with a large lahar?
Nevado Del Ruiz, Columbia 1985
49
What was the date of Nevado Del Ruiz, Columbia?
13th November 1985
50
What were the social impacts of the Columbia eruption?
estimated 23,000
51
What were the events of the Columbia eruption?
- evacuation was ordered but was then abandoned as the volcano reduced activity - the summit of the volcano is covered by snow which thawed during the eruption - lahar occurred at night where residents were sleeping = increased vulnerability - in total 4 towns were buried, worst affected = Armero
52
What is the example of a lava flow eruption?
Nyiragongo, Democractic Republic of Congo (LEDC)
53
When was the date of the eruption of Nyiragongo?
22nd Mat 2021
54
What was the tectonic setting of Nyiragongo?
Constructive boundary
55
What where the social impacts of the eruption in Nyiragongo?
32 deaths
56
What where the primary impacts of Nyiragongo?
- 450,000 people were displaced or evacuated - 17 villages were directly impacted by lava flows destroying homes, school and medical centres
57
What where the secondary impacts of Nyiragongo eruption?
- earthquake occurred in the days following causing damage to property and infrastructure - co2 gases were released and built in low lying areas - 8000 people migrated to Rwanda -10 people killed during the evacuation
58
What were the primary responses of Nyiragongo?
charities supported the search and rescue operations
59
What were the secondary responses of the Nyiragongo eruption?
- 6 temporary camps where set up by gov, but these were damaged by heavy rainfall - UNHCR supported 13 families with accommodation in the city of Goma - Charities raised money to rebuild homes
60
What is the definition of a lava flow?
can erupt as lava flows when its runny, as steep sided domes , moves relatively slow (made if molten rock)
61
What is an example of an eruption that had a lava flow in a MEDC?
Kilauea, Hawaii (MEDC)
62
What are the hazards and causes of a lava flow?
- moves slowly, rarely a direct threat to people - high viscosity = high silica content - takes a long time for lava flows to cool completely - damage property, bury cars, homes and vegetation
63
What was the date of the Kilauea eruption?
May - August 2018
64
What were the social impacts of the Kilauea eruption?
o deaths, 2000 people displaced
65
What where the events of the Kilauea eruption?
- lava flows spread, covering 13.7 sq miles of surrounding land - created 875 acres of new land - 700 homes were destroyed - Kilauea caldera collapsed as a result of 60,000 earthquakes caused by rising magma
66
What was the positive of the Kilauea eruption?
By April pressure had increased so much that the lava lake significantly increased in size drawing over 10,000 visitors per day to the park
67
What is the definition of a volcanic slide?
(can transform into lahar if its significant) volcanoes are steep and unstable, when there is an eruption there are frequent landslides
68
What are the hazards and causes of volcanic landslides?
- large scale avalanches often occur on steep slopes - the larger the debris avalanche the faster it moves - they can dam rivers and lakes - could possibly lead to a tsunami
69
What is the example of an eruption with a volcanic landslides?
Mount St Helens, USA
70
When was the eruption of Mount St Helens?
27th March 1980
71
What was the tectonic setting of Mount St Helen eruption?
Destructive plate boundary
72
What was the VEI of the Mount St Helen eruption?
VEI 5
73
What were the social impacts of the Mount St Helen eruption?
57 deaths - occurred in a sparsely populated area, so relatively few people where affected, however local unemployment increased
74
What where the impacts of the Mount St Helen eruption?
- volcanic landslide covered 23 sq miles and travelled up to 150mph - transport infrastructure was damaged, reducing the ability to move - 1000 flights were cancelled due to airborne ash
75
What where the economic impacts of the Mount St Helen eruption?
total economic costs were $1.1 billion, however lead to an increase in tourism
76
What were the responses of the Mount St Helen eruption?
- an immediate response was evacuation by emergency services - a long term response was to allow the area to naturally recover and establish a National Monument protected area - increased monitoring to mitigate impacts in the future
77
What is the definition of volcanic toxic gas?
bubble out of lava to escape through soil or vents in the ground some of the more poisonous gases can form acid rain
78
What are the hazards and causes of volcanic toxic gas?
- can cause breathing problems - can release toxic chemicals into the atmosphere = co2 and sulfur dioxide - acid rain = large amounts of gases sometimes build up in low lying areas and can asphyxiate livestock and harm vegetation
79
What is an example of a volcanic eruption that involved release of toxic gases?
Lake Nyos, Cameroon
80
When did the volcanic eruption in Lake Nyo's occur?
22nd August 1986
81
What was the tectonic setting of the Lake Nyos eruption?
lake sits in the crater of an extinct volcano
82
What were the social impacts of the Lake Nyos eruption?
1746
83
What where the impacts of the Lake Nyos eruption?
- a quarter of a cubic mile of co2 was released - the event occurred at night, the co2 gas asphyxiated the residents of the villages along with 3500 livestock up to 25km away
84
What were the responses of the Lake Nyos eruption?
- in 2001 pipes were installed to degas the lake in a controlled manner, today 20% of the gas has been released - the lake is now constantly monitored and an early warning system has been installed
85
What is an example of a gas eruption?
White Island, New Zealand
86
What was the date of the White Island eruption?
9th december 2019
87
What was the tectonic setting of the White Island eruption?
a convergent subduction zone, part of the ring of fire
88
What were the social impacts of the White Island eruption?
21 deaths 26 were injured death and injuries were caused from burned lungs from inhaling sulfur dioxide and volcanic ash and deep-tissue burns
89
What were the impacts of the White Island eruption?
most of the victims were tourists, and little residents - the 'phreatic' eruption involves the release of steam and volcanic gases which cause an explosion, launching rock and ash 3km into the air
90
Why were there no warnings, for the White Island eruption?
The eruption is not caused by magma, but by steam and this is much harder to predict
91
What was the search and rescue for the White Island eruption?
23 people rescued from the island, estimated there was less than 50 on the island at the time of the eruption - seven helicopters dispatched
92
Why where the island owners of White island prosecuted after the eruption in 2019?
In October 2023, the owners (Whakaari Management Limited) were prosecuted, claiming that the risk assessments in place were inadequate given that the volcano could erupt at any time
93
What is the definition of a jokullhlaups?
are large abrupt floods of water from glacial lakes or from beneath glaciers that may be triggered when a volcano erupts under a glacier (GLOFS)
94
What are the hazards and causes of Jokulhlaups?
- wide spread landform modification = erosion and deposition - flooding due to rapid release of water, 'megaflood'

Tectonics (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions