Earthquakes + Volcanoes Flashcards
(97 cards)
1
Q
Is Continental or Oceanic crust more dense?
A
Oceanic crust
2
Q
Is Continental or Oceanic crust higher in silica?
A
Continental crust
3
Q
Will older or newer oceanic crust subduct?
A
Older oceanic crust
4
Q
What makes up the lithosphere?
A
The upper part of the mantle and the continental/oceanic crusts.
5
Q
Does silica make a rock more or less dense?
A
Less dense
6
Q
Would a high viscosity liquid have a quick or slow flow?
A
Slow flow (water is low viscosity)
7
Q
Would a light-colored rock have a high or low silica content?
A
High silica content
8
Q
Would a dark-colored rock have a high or low silica content?
A
Low silica content
9
Q
Would a low viscosity liquid have a quick or slow flow?
A
Quick flow (honey has a high viscosity)
10
Q
Does a mafic rock have high or low density?
A
High density
11
Q
Does a felsic rock have high or low density?
A
Low density
12
Q
Does a mafic rock have a high or low silica content?
A
Low silica content
13
Q
Does a felsic rock have a high or low silica content?
A
High silica content
14
Q
Which rock would be lighter in color: mafic or felsic?
A
Felsic
15
Q
Which rock would be darker in color: mafic or felsic?
A
Mafic
16
Q
Will magma with a high silica content have a high viscosity or low viscosity?
A
High viscosity (slow flow)
17
Q
Will magma with a low silica content have a high viscosity or low viscosity?
A
Low viscosity (quick flow)
18
Q
What is a magma’s viscosity affected by?
A
-Silica (more silica-slower flow)
-Temperature (hotter-faster flow)
-Gases (more gases-faster flow)
19
Q
Will magma with a higher temperature have a high viscosity or low viscosity?
A
Low viscosity
20
Q
Will magma with a lower temperature have a high viscosity or low viscosity?
A
High viscosity
21
Q
What percent of basaltic magma is silica?
A
50% or less
22
Q
What percent of andesitic magma is silica?
A
50%-70%
23
Q
What percent of rhyolitic magma is silica?
A
70% or more
24
Q
List the 3 types of magma in order from lowest viscosity to highest viscosity.
A
Basaltic, Andesitic, Rhyolitic
25
List the 3 types of magma in order from highest silica content to lowest silica content.
Rhyolitic, Andesitic, Basaltic
26
Viscosity
The resistance to flow (how well a liquid flows).
27
Who proposed continental drift?
Alfred Wegner
28
What does the theory of plate tectonics state?
The earth's lithosphere is broken into pieces that are in constant motion on the asthenosphere.
29
On average, how far do plates move per year?
A couple centimeters
30
Evidence of plate tectonics:
-Fossils of the same animals in South America + Africa.
-Fossils of tropical plants in Antarctica.
-Evidence of glaciers in the tropics.
But mostly...
-Map of the ocean floor.
-Map of all volcanoes + earthquakes.
31
Divergent boundary on an oceanic plate.
Splits and erupts basaltic lava. However, the plates are moving too quickly to turn into a shield volcano, but does leave a ridge on the ocean floor.
32
What is a divergent boundary on an oceanic plate called?
A Ridge
33
What is a divergent plate on a continental plate called?
A Rift or a spreading center
34
Divergent boundary on an continental plate.
Plate gets stretched and becomes thinner and thinner (creating a big valley) until it starts oozing basaltic lava and essentially becomes a shield volcano.
35
Convergent on Continental/Continental.
Creates big mountains above ground and in the mantle. NO VOLCANOES.
36
What kind of magma does a divergent boundary erupt?
Basaltic
37
Convergent on Continental/Oceanic.
The oceanic plate is more dense and therefore subducts, which creates lots of earthquakes. The plate melts and creates andesitic magma, which is less dense than basaltic magma so it rises and creates a chain of volcanoes parallel to the plate boundary. The spot where subduction occurs is also where there is a very deep trench.
38
Divergent plates do what?
Spread apart.
39
Convergent plates do what?
Run into each other.
40
Convergent on Oceanic/Oceanic.
The older oceanic plate is more dense and therefore subducts, which creates lots of earthquakes. The plate melts and creates andesitic magma, which is less dense than basaltic magma so it rises and creates a chain of volcanoes parallel to the plate boundary. The spot where subduction occurs is also where there is a very deep trench.
41
What kind of magma do shield volcanoes erupt?
Basaltic magma
42
What does a shield volcano look like?
Wide base and gentle slope.
43
What types of volcanoes are found at subduction zones?
Stratovolcanoes
44
What kind of volcanoes are often found on other volcanoes?
Cindercones
45
What do stratovolcanoes look like?
Small base, steep sides.
46
What do cindercones erupt?
Chunks of rock.
47
What do stratovolcanoes erupt?
Rhyolite/Andesite
48
What is a fissure?
Cracks where magma reaches the surface.
49
What is a caldera?
A volcano that emptied its chamber and collapsed in on itself, creating a basin.
50
How do transform boundaries move?
They move side by side, one moving in one direction and the other in the opposite.
51
What happens at a transform boundary fault?
Lots of earthquakes but no mountains or volcanoes.
52
How is rhyolitic magma made?
When a magma chamber gets stuck in continental crust and melts in a lot of high-silica rock and so the magma becomes higher in silica.
53
What is an effusive eruption?
An eruption with lava flows.
54
What is a pyroclastic eruption?
When the volcano erupts ash and rock.
55
Are hot spot volcanoes dependent on plate tectonics?
No.
56
How are hot spot volcanoes formed?
A plume of magma comes up into the crust and erupts. The plate moves and more volcanoes are created as the plate moves. The volcanoes that have moved off of the hot spot are extinct.
57
What is a hot spot track?
A train of mountains caused by a hot spot.
58
What kind of magma does a hot spot volcano erupt?
Normally andesitic or rhyolitic because it melts in continental crust, but it can be basaltic too.
59
Where is Iceland (geology-wise)?
On the middle of an ocean boundary and has a hot spot.
60
How is a volcano likely to erupt?
The same way that it did in the past.
61
What are signs a volcano might erupt?
-Increases in ground heat
-Ground deformation
-Earthquakes (magma moving around beneath the surface)
-Gases coming out of the volcano (steam, sulfur, carbon dioxide)
62
What kind of magma is mantle magma?
Basaltic
63
Why would a volcano erupt basaltic lava?
-Hot spot volcanoes (but not normally)
-Divergent boundaries (Ocean and Continental)
64
Why would a volcano erupt andesitic lava?
-Melting of a subducting ocean plate (o/o or o/c)
-Hot spot volcanoes
65
Why would a volcano erupt rhyolitic lava?
-Hot spot volcanoes
66
What is a bomb?
A large chunk of rock that comes out of a volcano that is solid on the outside and molten on the inside.
67
How does a pyroclastic flow form?
The volcano erupts a large column of ash into the sky. When the volcano stops erupting ash, the column has no support and comes crashing down the side of the volcano.
68
What is a lahar?
When snow melts and mixes with dirt to create a super-hot, super-fast mudflow.
69
What does a volcanic earthquake look like?
A sharp up and down (ground breaks) and then little waves (magma fills gap).
70
What happens if a volcano releases carbon dioxide?
The carbon dioxide is more dense than air and pushes all the air out so people near the base of the volcano suffocate.
71
What day did Mt. St. Helens erupt?
May 18, 1980
72
Stress
A force, a push/pull (what moves the crust)
73
Strain
How the rock deforms (because of stress)
74
Where is the ring of fire?
Around the Pacific Ocean.
75
Plastic deformation
The stretched rocks will not snap back.
76
Elastic deformation
The stretched rocks snap back.
77
Hanging wall
The wall that is above you.
78
Foot wall
The wall that you are on.
79
Strike slip fault
Transform boundary
80
Reverse fault
Convergent boundary
81
What kind of stress is a reverse fault?
Compressional stress
82
How does the hanging wall move in a reverse fault?
The hanging wall moves up.
83
Normal fault
Divergent boundary
84
What kind of stress is a normal fault?
Tensional stress
85
How does the hanging wall move in a normal fault?
The hanging wall moves down.
86
What kind of stress is a strike slip fault?
Shearing stress
87
How does the hanging wall move in a strike slip fault?
Side to side.
88
Focus
How deep below the surface the rocks break in an earthquake.
89
Epicenter
The place on the surface above the focus (where the earthquake is the strongest).
90
Can we predict earthquakes?
NO.
91
P Waves
Primary waves: moves up and down, reaches the surface first.
92
S Waves
Secondary waves: Rolls like a wave, comes from the focus.
93
Liquefaction
When the movement of the earthquake pushes groundwater up to the surface and turns the soil into mud which can cause heavy structures to sink.
94
How does an earthquake cause a tsunami?
It pushes water back which causes a big wave.
95
What causes earthquakes?
As plate move, the rock catches on each other. Pressure builds up and suddenly releases (earthquake).
96
What is continental crust made of?
Granite
97
What is oceanic crust made of?
Basalt
