EES 150 exam 3 Flashcards
(128 cards)
1
Q
What has to be true for the cause of volcanoes due to Ocean-continent subduction zones?
A
.It has to be a continent
.Near a subduction zone
2
Q
What has to be true for the cause of volcanoes due to Ocean-ocean subduction zones?
A
.It’s in the ocean
.Near a subduction zone
3
Q
How did many people die by the Vesuvius volcano in Pompeii?
A
.Poisonous gas
.Buried by flows of hot ash
4
Q
Is the Vesuvius volcano an volcanic islands or arc?
A
Volcanic arc
5
Q
What 2 groups of people are most likely to get killed by volcanic activity?
A
.Volcanologist
,Photographers
6
Q
What’s magma?
A
Melted rock material below the surface
7
Q
What’s lava?
A
Melted rock that erupts at the surface
8
Q
How is volcanic activity linked to tectonics?
A
.Magma chemical composition
.Ability to flow
.Gas content
.Volume
9
Q
What factors are determined in whether a volcano is peaceful or explosive?
A
.Magma chemical composition
.Ability to flow
.Gas content
.Volume
10
Q
What’s a volcano?
A
A place where lava flowed onto the surface whether it’s visible or not
11
Q
What’s an active volcano?
A
A volcano that has erupted in historic times (or at least within the last 10,000 years)
12
Q
What’s a dormant volcano?
A
A volcano that has not erupted recently but geologically is likely to do so again
13
Q
What’s an extinct volcano?
A
A volcano that is geologically unlikely to erupt again
14
Q
What form of rocks are volcanic rocks?
A
Igneous
15
Q
Do volcanic rock have homogenous or heterogeneous appearance?
A
homogenous
16
Q
Viscosity
A
Internal resistance to flow
17
Q
Volatile
A
Abundance controls explosiveness (gasses escaping)
18
Q
Volume
A
Influences severity eruption (small or large)
19
Q
Nonexplosive eruptions
A
Icelandic & Hawaiian
20
Q
Somewhat explosive
A
Strombolian
21
Q
Explosive
A
Vulcanian & Plinian
22
Q
Volcanic Explosivity Index
A
A way to evaluate eruptions of a scale of 1-8, according to 3 variables
23
Q
Large VEIs have what
A
High volumes of ejecta
24
Q
Flood basalts
A
Low viscosity, low volatiles, & very large volume.
Largest volcanic event and possibly the initial stages of a mantle plume
25
Causes of eruptions
Melting rock expanding in volume because of decrease in pressure
Gas escaping when magma rises
26
Global effects of flood basalts
CO2 & SO2 released into air
27
Why does flood basalts produce so much climate-changing gases
A lot of lava= a lot of gas
28
Icelandic-type eruption
Low water content & low viscosity (basalt). Very peaceful eruption from fissures and produces a "curtain of fire effect"
29
Example of Icelandic-type eruption
Krafla (1970s)
30
Hawaiian type eruption
Low water content & low viscosity (basalt). Higher lava fountain, low cones, and may last for years as lava flows slowly. Property may be destroyed
31
Main island of Hawaii includes what 5 volcanoes
Loa, Mauna, Hualalai, Mauna Kea, & Kilauea
32
Shield volcanoes
Low viscosity, low volatile, & large volume basaltic lava flows
Thin layers, very broad, great width compared to height
33
Phreatic eruption
Interaction of hot volcanic rocks and water (rare Hawaiian eruption)
34
Strombolian-type eruption
Short-lived explosion outbursts of pasty lava ejected 10s-100s m into air
35
Scoria Cones
Medium viscosity, medium volatility, & small volume
From through strombolian eruptions
(basaltic and andesitic lava)
36
Scoria cones are composed of what
Tephra (volcanic debris)
37
Where does the name Strombolian eruption come from
Stromboli volcano in Italy
38
Vulcanian-type eruption
Alternates between highly viscous lava flows and pyroclastic eruptions
39
Plinian-type eruption
Produce gas-powered vertical columns of pyroclastic debris up to 50 km into atmosphere
40
Starto-
Layered
41
Stratovolcanoes
Result of high viscosity, high volatiles, large volume from vulcanian to plinian eruption, gas-rich andesitic to rhyolitic magma
42
Stratovolcanoes are found where?
At subduction zones where magma is generated
43
Volcano weather
Steam cools, condenses, and falls as rain
44
lahars
Rain mixing with ash on volcano's slopes
45
Volcano weather can produce...
lightning
46
Volcanic ash from plinian eruptions is hazardous to...
airplanes
47
lava domes
high viscosity, low volatiles and small volume eruptions that happen after Vulcanian/Plinian eruption
48
lava domes and low volatiles
Gases escape during the larger eruption and the low-gases left cools in place forming a plug
49
Why has a lava dome formed inside the crater of Mt. St. Helens?
Because the gas is gone
50
A typical stratovolcano eruption sequence
Vulcanian precursor -> Plinian main event -> lava dome conclusion
51
Vulcanian precursor
Gas- rich material shoot out first
52
Plinian main event
Gas depletes
53
Lava dome conclusion
High-viscosity magma build lava dome
54
Calderas
Result from high viscosity, high volatile, and very large volume
55
Where are calderas?
The summit of volcanoes and collapse of a stratovolcano
56
Giant continental calderas are associated with what?
Mantle plumes
57
Resurgent Caldera form where?
Where calderas have preciously formed
58
Where do magma erupt at mantle plumes?
Material comes from the Earth's melted center
59
Columbia river plateau basalt
River has eroded down through them in many places
60
Cycle of mantle plumes
Early on mantle plumes spread out and is very hot; later it cools down and affects a smaller area
61
Oceanic plateau
A massive flood basalt from a mantle plume beneath an oceanic plate
62
Eruption styles and frequencies between California and Hawaii
California- continental crust
| Hawaii- Oceanic crust
63
Most active volcano in Hawaii
Kilauea
64
Iceland is on what?
Mid-ocean ridge (above sea level) & mantle plume
65
Shallow earthquakes are associated with what?
Movement of magma
66
Volcanic eruption in 1973, Island of heimaey & it's harbor
Lava flow blocked harbor, part of town buried, & 5.5 billions tons of sweater used to cool and redirect lava flow
67
What's responsible for opening up the North Atlantic?
Iceland mantle plume
68
Plutonic igneous rocks
Cool slowly below the surface
69
Volcanic igneous rocks
Cool quickly at/ near the surface
70
What elements are abundant in the composition of magma?
Iron- Oxygen-> Silicon-> Magnesium-> other
71
Why do igneous rocks and magmas have different compositions?
.Magma mixing
.Melting of surrounding rock & incorporation into magma body
.Partial melting
.Fractional crystallization
72
Partial melting
Where low temperature minerals melt first
73
Where do volcanoes form?
.At subduction zones(10%)
.Mantle plumes(10%)
.Mid-Ocean ridges(80%)
74
How does magma from mid-ocean ridges form?
Partial melting due to the mantle due to lower pressure
75
How does magma from mantle plumes form?
Partial melting due to the mantle eventually causing a mid-ocean ridge to form or overriding plate
76
Where are volcanoes usually not found?
.continent-continent convergent plate boundaries
| .Transform plate boundaries
77
Pyro-
fire
78
-clastic
broken up
79
What's one control on viscosity?
temperature
80
What makes an eruption more explosive?
Dissolved gases (including water)
81
3 types of magma/lava
Rhyolitic, Andesitic, & Basaltic
82
Basaltic lava
Highest temperature, lower SiO2, low viscosity, low gas, erupt peacefully, frequent, flows long distances, low pressure, & lower minerals melting points
83
Where does basalt form?
Mid-ocean ridges
84
Andesitic/ Rhyolitic
Lower temperatures, higher SiO2, more viscous, dangerous eruptions, high gas, lava flows slowly and not far, presence of water, & partially melting oceanic crust
85
What produces andesitic lava?
Partially melted basaltic oceanic crust at subduction zones
86
Rhyolitic magma
Highest gas and erupts explosively
87
Calcium/Sodium rich minerals depend on what?
temperature
88
Which lava has the most complex arrangement of bonded silica tetrahedral?
Andesitic/Rhyolitic
89
Example of Basaltic eruptions
Mauna Lao, Hawaii
90
Features of Basaltic eruptions
Pahoehoe, A'a, Lava tubes, Columnar jointing, System of Polygonal Cracks
91
Pahoehoe
Flows hot lava beneath the skin & the skin just piles up while cooling
92
A'a
Lava flows farther away from volcano when it's cooled down, thicker crust & lava still flows, & lava breaks and deform
93
Lava tubes
Cools more quickly but lava continues to flow beneath
94
How does a lava tube form?
Cooling (crystalizing) forms crust above it and lava tube becomes a cave
95
Columnar jointing
Are results as basaltic lava flows & contract (looks supernatural) that have equally spaced centers
96
System of Polygonal Cracks
Lava cools & decease volume
97
Volcanic neck
Lava that cooled & crystallized inside a volcano that can be seen after the outside layers of the extinct volcano have eroded away
98
Andesitic/Rhyolitic volcanoes form near?
Subduction zones
99
Features of Andesitic/Rhyolitic eruptions
Pyroclastic debris, volcanic ash, tuff/ tephra, pyroclastic flow, & volcanic gases
100
Pyroclastic debris include
Volcanic ash, bombs, Lahar, & blocks of pre-existing volcano
101
Bombs
Large blobs of lava
102
Volcanic Ash
Little shards of lava that form a glasslike substance. Shattered rock
103
Pyroclastic flow
Fast moving avalanche of hot tephra
104
Tephra/ Tuff
A deposit of pyroclastic material which welds together to form the rock Tuff
105
Lahar
When tephra mixes with water causes deadly flow (like muddy water)
106
Volcanic gases
Water, Co2, H2S, SO2
107
Vescular texture
Gas bubbles escaping from cooling lava
108
What do volcanoes make the most of on Earth?
Water
109
Mantle Plume melting
Partial melting on mantle, partial mantle on crust, or complete melting of crust
110
Triggers of mantle plume melting
Deceased pressure, rocks rise, & expansion of volume
111
Icelandic composition
Low water & viscosity (basalt)
112
Hawaiian composition
Low water & viscosity (basalt)
113
Strombolian composition
Moderate water & low to moderate viscosity (basalt to andesite)
114
Vulcanian composition
Moderate to high water & moderate to high viscosity (basalt to rhyolite)
115
Plinian composition
High water and viscosity (Andesite to rhyolite)
116
What are the 4 primarily ways to volcanoes and kill?
Pyroclastic flow
Tsunami
Lahar
Indirect (famine)
117
Why does Pyroclastic flow happen?
.Eruption column collapse
.Collapse of a dome
.Overspilling the crater rime
.Direct blast of pyroclastic material
118
Mt. Pelee
Pelee- peeled or baled
119
St. Pierre
Completely destroyed
2 survived
Stayed because of election
120
nuee ardente
Glowing cloud
121
Glowing cloud refers to...
Hot, glowing volcanic fragments, & 700 degrees Celsius when it hit St. Pierre
122
Volcanoes that produce pyroclastic flow
Rhyolitic
123
Santa Cruz volcano
No subduction zone
| Mantle plume
124
Krafla volcano
Fluid lava
125
Lewatobi Volcano
Subduction zone
| Andesitic
126
Other ways of volcanic deaths
Gas
127
How are craters formed?
Volcanic gases
128
Climate changes caused by volcanoes
.Volcanic ash-> global cooling
.Sulfuric acid-> acid rain
.CO2-> global warming
