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EAS 205 > Volcanoes 3 and 4 > Flashcards

Volcanoes 3 and 4 Flashcards

1
Q

How do volcanic eruptions cause short term cooling effects?

A
  1. sulfur enters stratosphere and forms tiny H2SO4 droplets (aerosols)
  2. aerosols (high albedo) reflect, scatter, and absorb solar radiation
  3. troposphere cools
  4. stratosphere warms
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2
Q

which chemical from volcanic eruptions destroys the ozone layer?

A

chlorine

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3
Q

What is the largest eruption of the satellite era?

A

Pinatubo (Phillipines) 1991

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4
Q

What does “optical depth” describe?

A

how much sunlight get through atmosphere; dimensionless

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5
Q

TRUE or FALSE: eruptions in the tropics are more likely to have global impacts.

A

TRUE

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6
Q

By how many degrees did global average temperatures drop due to the Pinatubo eruption? How long did full recovery take?

A
  • lower by 0.6 degrees
  • 4-5 years for full recovery
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7
Q

Does mafic or felsic eruption have more sulfur?

A

mafic

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8
Q

Which volcanic eruption had the highest volcanic explosivity index?

A

Toba

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9
Q

which eruption was ranked #2 for historical eruptions? How much sulfur was released? What was the significance of this eruption?

A
  • krakatoa
  • 80 Tg SO2
  • connection between eruption and following cold winter; The Scream
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10
Q

Which eruption is associated with “the year without summer”? How much sulfur was released?

A
  • Tambora
  • > 100 Tg or SO2
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11
Q

What did the Smithsonian collection show?

A

eastern USA during “the year without summer” –> spur migration and colonization of the western USA

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12
Q

What was the name of the poem written by Lord Byron that may have been inspired by Tambora?

A

Darkness

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13
Q

Which volcano in Iceland erupted for 8 months? How much sulfur was released? what kind of volcano is it?

A
  • Laki
  • 120 Tg of sulfur (4x Pinatubo)
  • fissure
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14
Q

Even though Toba could be deemed a super eruption, were there long term effects? Why or why not?

A

no long term effects b/c single injection and residence time of sulphate aerosols are limited

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15
Q

What is the largest contributor to short-term NATURAL climate variability over the Holocene?

A

volcanoes

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16
Q

How was the Little Ice Age triggered and sustained?

A

triggered by volcanism; sustained by sea-ice/ocean feedback (albedo effect)

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17
Q

What do large igneous provinces (LIPs) represent? What kind of tectonic feature are they associated with?

A

times when large volumes of (mostly) mafic magmas were generated and extruded onto the landscape; associated with hot spots/mantle plumes

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18
Q

What are some other names for LIPs?

A

continental flood basalts, volcanic rifted margins, oceanic plateaus, ocean basin flood basalts

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19
Q

What are some other names for LIPs?

A

continental flood basalts, volcanic rifted margins, oceanic plateaus, ocean basin flood basalts

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20
Q

What is the maximum lifespan of LIPs?

A

50 Myr

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21
Q

Which LIP is found in Nova Scotia? Which Park is this? What does the white line of this LIP mark?

A
  • CAMP LIP at Five Islands Provincial Park
  • white line marks the Triassic-Jurassic boudnary
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22
Q

What do most masse extinctions have in common?

A

LIPs (except end ordovician)

23
Q

Which LIP is associated with these mass extinctions?

  • end devonian
  • end permian
  • end triassic
  • end cretaceous
A
  • end devonian: Villu/PDD LIP
  • end permian: Siberian Traps LIP
  • end triassic: CAMP LIP
  • end cretaceous: Deccan Traps LIP
24
Q

What climatic issues (beyond cooling and warming) do persistent eruptions cause?

A
  • ocean acidification (CO2)
  • ocean anoxia
  • acid rain
  • gas and light blocking impacts on terrestrial ecosystems (photosynthetic shutdown)
25
Q

What are some distinctive features that are commonly seen in t he geologic records of most major exticntions?

A
  • loss of carbonate deposition in oceans (acidification)
  • negative carbon isotopic excursions
  • spikes in metal deposition
  • other isotopic excursions
26
Q

which peak extinction event is the best analogue for rapid CO2 release by human activities?

A

paleocene-eocene thermal maximum (PETM) and NAIP

27
Q

What are the steps of long term carbon cycling? What is the net result? What is the name for this process?

A
  1. silicate weathering
  2. carbonate precipitation
  3. CO2 dissolution in ocean

net: silicate weathering on land and carbonate precipitation in the sea (i.e. CO2 –> CaCO3) –> NATURAL CARBON SEQUESTRATION

28
Q

What are 2 other names for the long term carbon cycling process?

A
  • silicate-carbonate weathering cycle
  • carbon-silicate geochemical cycle
29
Q

What keeps the carbonate-silicate geochemical cycle going? Explain. What is the reverse of the net result of silicate weathering?

A
  • plate tectonics keep the cycle going: carbon-bearing rocks are subducted and undergo metamorphism, mid-ocean ridges and volcanoes return CO2 to the ocean and atmosphere
  • reverse of silicate WEATHERING = carbonate METAMORPHISM
30
Q

How do we get out of snowball earth?

A

volcanoes release CO2 emissions that accumulate in the atmosphere and increase GHG warming effects

note: required b/c no weathering (no rain)…only metamorphism

31
Q

What is glacial pump? Where can it be observed?

A
  • where volcanism increases in response to deglaciation and isostatic rebound
  • observed in Iceland and Mount Edgecumbe in SE Alaska
32
Q

Which 3 arcs (sub-duction zone volcanoes) may be impacted by large-scale glaciation?

A
  • cascades
  • southern Andes
  • Kamchatka

(note: NOT Alaska)

33
Q

which climate perturbation in the Holocene does the Cook Inlet region eruption frequency correspond with?

A

8.2 ka event

34
Q

What are Milankovitch cycles? What do these cycles cause?

A
  • changes in Earth’s tilt, precession, eccentricity control solar energy distribution on earth surface
  • cause positive feedback that triggers transition to glaciation
35
Q

How are Milankovitch cycles counteracted and why?

A
  • milankovitch cycles cause glaciation which can lead to snowball earth
  • counteract: as glaciers grow on land, sea levels drop
36
Q

What is the evidence for milankovitch cycles?

A

enhanced eruption frequency at ocean spreading centers during/at end of glaciation

37
Q

What is the difference between eruption frequency of subduction (arc) volcanism adn terrestrial volcanism?

A
  • subduction (arc) volcanism: peak prior to or during deglaciation
  • terrestrial volcanism: peak after deglaciation
38
Q

What is the problem with volcanoes?

A

“Low probability, high consequence events”

39
Q

What are the steps in understanding the hazard and managing the risk?

A
  1. studying the geological record
  2. monitoring
  3. modelling and experimentation
40
Q

What is key in determining eruption frequency and magnitude (VEI)?

A

mapping tephra

41
Q

What type of map is produced when tephra is mapped?

A

isopach maps

42
Q

Which volcano is the 16th most deadly volcano in the world?

A

mount rainier

43
Q

From mount rainier, where can lahars reach to?

A

Puget Sound

44
Q

what are some signs of moving magma that may still be at greater depths (deep inflation)?

A
  1. elevated CO2 emissions
  2. deep long-period (DLP) earthquakes caused by moving magma
  3. aseismic inflation, caused by magma accumulation
  4. changes in water chemistry and thermal output
45
Q

What are some signs that magma has entered shallower storage areas and unrest may intensify?

A
  1. inflationary ground deformation increases
  2. volcano-tectonic (VT) seismicity
  3. ground cracking, glacier melting, increase spring discharge and thermal output
  4. significant sulfur degassing
  5. at “wet” volcanoes, sulfur gases change from H2S to SO2, as groundwater is driven off by rising magma and other highly soluble gas species
  6. phreatic explosions
46
Q

What does key monitoring equipment include?

A
  • seismometers
  • tiltmeters
  • GPS
  • gas monitoring stations
  • airborne surveys
  • remote sensing space and aircraft
47
Q

What is a well known volcanic monitory program within the Geologic Survey? Is Canada a part of it?

A
  • USGS
  • Canada NOT a part of it
48
Q

What is a major incentive of ash-fall modelling?

A

airline safety

49
Q

What is an event tree?

A

all data and various models are integrated to make an event tree, which allows for predictions

50
Q

what was the main reason for deaths from Mount St Helens? where did most people die?

A
  • politics and pressure from forestry giant, Weyerhaeuser
  • most people who died were OUTSIDE the red zone (pyroclastic flow deposits)
51
Q

What happened with the sediment retention dam on the Toutle at Mount St. Helens?

A
  • originally built to capture future lahars and floods and sediment
  • excess sediment silted up of Columbia and raised the Cowlitz base level –> LEVEES USESLESS –> VERY EXPENSIVE DREDGING
52
Q

Which volcano in Guatemala erupted on June 3, 2018? were there warnings?

A
  • Fuego
  • only voluntary evacuation order was given
53
Q

which volcano in New Zealand erupted on Dec. 9, 2019? were there warnings? was access limited

A
  • White Island
  • almost a month before, issued the highest alert level (2); access was NOT limited
54
Q

Which volcano started erupting on Jan. 12, 2020 in the Philippines? were there warnings?

A
  • Taal volcano
  • volcano alert issues on increased shallow earthquakes; no fatalities, massive economic impact

EAS 205 (16 decks)

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