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Geography: Hazards > volcanic hazards > Flashcards

volcanic hazards Flashcards

1
Q

Can you give some primary volcanic hazards

A

Eruption column (cloud of tephra and gasses)
Volcanic gases
lava flows
nuées ardente / pyroclastic flow
Tephra

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2
Q

give an example of a case involving an eruption column

A

Chaitén, Chile, 2008.

Typical of plinian eruptions.

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3
Q

give an example of a case study involving a lahars

A

Nevado del Ruiz destroyed Colombian town of Armero.
1985.

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4
Q

give a case study involving volcanic landslides

A

Mt. St. Helens eruption - largest volcano landslide!

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5
Q

Give a case study with large pyroclastic flows

A

Pompeii?
79AD
Vesuvius.

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6
Q

Give a case study of lava flows

A

Erupting basaltic since 1983
Kilauea volcano
Hawaii
Lava flows destroying almost 200 houses.

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7
Q

Give a case study with volcanic gases

A

1986 -
Lake Monoun (Cameroon) contaminated 1,700 die.

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8
Q

What’s the difference between EFFUSIVE and EXPLOSIVE eruptions?

A

EFFUSIVE: molten rock ejected - small eruptions
EXPLOSIVE: rock ejected. - big eruptions!

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9
Q

Each step in the VEI (?) scale represents an explosivity increase of how much?

A

VEI - volcanic explosivity index
10X more than previous rating.
10-100-1000 (tenfold)

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10
Q

Give some secondary hazards

A

Lahars
Flooding
Tsunamis
Avalanches
Landslides
Climactic change (1991 mount Pinatubo lowered global temps by 1 degree C!)

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11
Q

Give 3 short term impacts of eruptions

A

disease
can make geothermal energy
environmental devastation

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12
Q

give 2 long term impacts of hazards

A

Nutrient rich soil
tourism - Vesuvius.

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13
Q

Impacts of eruptions (SEEP)

A

Social: homes + land destroyed. Death + disease.

Environmental: acid rain

Economic: Buildings + businesses destroyed.

Political: mistrust gov.

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14
Q

list the VEI in order

A

Icelandic
Hawaiian
Strombolian
vulcanian
pelean
Plinian
Ultra plinian

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15
Q

where can one locate a volcano…

A

CONSTRUCTIVE (divergent) plate margins
- oceanic ridges (Mid Atlantic ridge) + The Great Rift Valley in East Africa. (created Kilimanjaro).

SUBDUCTION ZONES
- Ring of fire + Island arcs

HOT SPOTS
- Hawaiian islands - e.g Mauna Loa.

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16
Q

What are the 5 types of volcano?

A

basic shield - divergent - basaltic

acid dome - convergent - rhyolitic

composite - convergent - rhyolitic

Ash and cinder - convergent - basaltic

Caldera - Hotspots only - Basaltic

17
Q

monitoring a volcano

A

increase in release of gases

rise in level of lava lakes in volcanic craters

bulging upwards of surrounding land due to pressure

increasing number of small earthquakes (magma rising)

18
Q

why are some volcanoes more hazardous?

A

viscosity of magma
frequency of eruptions and risk perceptions
predictability
proximity to population centres
materials ejected
explosivity
plate margins

19
Q

Intrusive and extrusive volcanic activity?

A

IGNEOUS ROCKS
Intrusive - happens inside the volcano - form big crystals - granite.

Extrusive - happens outside - small crystals - pumice.

20
Q

3 preparation ideas

A

Land zoning
lava/lahar diversion channels
volcano - proof house - e.g roof support.

21
Q

ways to build resilience

A

mobile phone warnings
education
emergency services
stockpiling resources
practice drills.

22
Q

what equipment do scientists use to monitor volcanoes?

A

seismometer
tiltometers
radon gas levels
thermal imaging (like a pregnancy scan for a volcano :)
Magnetometer
drilling into volcanoes (can detect when last erupted due to gases)

23
Q

what are the 3 stages of the Park’s model?

A

Relief (hrs/days)
Rehabilitation (days/weeks)
Reconstruction (weeks/years)

24
Q

what is a seismometer/seismograph?

A

detects microwaves from increasing small e-quakes as magma rises.

25
Q

What is a tiltometer?

A

monitors how much the sides of the volcano have moved (flanks bulging with magma)

26
Q

what are Radon gas levels?

A

used to see how much sulpher dioxide is in the rick.

27
Q

What is a magnetometer?

A

see magnetism of the magma (magma contains magnetite - the reason for magnetic striping.)

28
Q

What is thermal imaging

A

Looks at magma levels within the volcano.

29
Q

what are the 3 types of lava?

A

Basaltic
Andesitic
Rhyolitic

Geography: Hazards (20 decks)

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