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EOSC 114 > Volcanoes 3 > Flashcards

Volcanoes 3 Flashcards

1
Q

name the four main types of volcanoes

A
  • cinder cones (m, ex)
  • shield volcanoes (m, non)
  • stratovolcanoes (int-f, mixed)
  • calderas / super volcanoes (f, ex)
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2
Q

True or false: diff types of volcanoes can exist together

A

true
ex/ small cinder cones on side of large shield volcanoes

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3
Q

which type of volcano can cause climate change?

A

calderas
(super volcanoes)

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4
Q

eruption type and trends for cinder cones

A
  • explosive
  • erupt for a few years then never again
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5
Q

size of cinder cones

A

height: < 0.5km
width: < 2km

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6
Q

cinder cones material, behaviour, slope

A
  • gas rich mafic (basalt)
  • fire fountaining creates beds of pyroclastic ejecta
  • angle of repose = 30-40˚ (not very steep)
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7
Q

eruption type and trends for shield volcanoes

A
  • effusive, not very explosive
  • erupts often
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8
Q

size of shield volcanoes

A

height: 4-10km
width: 100km

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9
Q

shield volcanoes material, behaviour, slope

A
  • mafic
  • lava flows (pahoehoe then a’a)
  • gentle slopes
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10
Q

eruption type and trends for stratovolcanoes

A
  • explosive
  • can erupt many times and stay active for 100k yrs
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11
Q

size of stratovolcanoes

A

height: < 5km
width: 10km

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12
Q

stratovolcanoes material, behaviour, slope

A
  • intermediate or felsic
  • interbedded lava flows, pyroclastic flows, lahars
  • steeper cuz viscous magma
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13
Q

example of stratovolcano

A

mt st helens
mt baker
mt fuji

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14
Q

example of shield volcano

A

Mauna Loa, hawaii

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15
Q

example of cinder cones

A

opal cone, garibaldi park

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16
Q

can we get felsic magma from the mantle?

A

no

17
Q

what causes stratovolcanoes? Where is it most common?

A

subduction
ring of fire

18
Q

how does plate subduction generate mafic/felsic magma?

A

plate subduction creates mafic magma
which melts crust to produce felsic magma

19
Q

eruption type and trends for calderas

A
  • explosive
  • not often
20
Q

size of calderas

A

huge!
up to 10’s km across

21
Q

calderas material

A

felsic pyroclastic

22
Q

how are calderas created

A

created from large, explosive felsic eruptions
when the roof of magma chamber collapses

23
Q

example of caldera

A

yellowstone

24
Q

what is a resurgent dome

A

when eruption causes a collapse (caldera), continued effusive eruption causes resurgent dome (usually in water)

25
Q

which type of volcano is the most explosive and most devastating?

A

calderas

26
Q

frequency of global eruptions for the four types of volcanoes (cinder cone, shield, strato, caldera)

A
  1. cinder cones -> frequent
  2. shield -> frequent/continuous,
    larger gaps btwn eruptions
  3. stratovolcanoes -> frequent but discontinuous
    (active vs dormant)
  4. calderas -> rare
27
Q

effusive eruption style

A

passive eruption of magma
- gas plume + pyroclastic material, pummus deposits

  1. laval flows
    (maf-int)
  2. lava domes
    (fel-int) ex/ mt baker
  3. gravitational collapse of flows/domes
    (block and ash flows)
28
Q

explosive eruption style

A

gas driven and violent
- pyroclastic deposits
- acid rain

  1. buoyant eruption column of ash
  2. pyroclastic airfall
  3. pyroclastic flows (column collapse)
  4. blocks & bombs (ballistics) proximal to vent
29
Q

volcano with sheets means ___ viscosity

A

low

30
Q

volcano with domes means ____ viscosity

A

high

31
Q

pyroclastic falls

A
  1. eruption columns: 10s of kms
  2. wide distribution of ash in downwind direction
  3. ash blankets topography

ex/ pinatubo

32
Q

pyroclastic flows

A
  • gas-pyroclast mixtures
  • gravity driven, channel in valleys
  • super hot and fast
  • velocity 40 to >400km/h
  • temps 100-600˚C
    ex/ pinatubo
33
Q

primary volcanic processes

A
  • lava flows, domes, graviational collapse
  • pyroclastic falls and flows
  • ballistics
34
Q

secondary processes

A
  • reworking of primary deposits during eruption
    -> LAHARS
35
Q

what are lahars

A

volcanic mud flows of water and ash
- super erosive and fast

EOSC 114 (30 decks)

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