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Geo of toursim > Lecture 7 - volcanoes > Flashcards

Lecture 7 - volcanoes Flashcards

1
Q

What are the two types of molten rocks

A

Magma and Lava rocks

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2
Q

Define a Magma rock

A

It is found deep within the crust and upper mantle

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3
Q

Define a Lava rock

A

flows from an erupting volcano

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4
Q

Lava is Not Magma on the earths surface? T or F?

A

False

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5
Q

How are volcanic rocks named

A

Volcanic rocks are named by the number of silica present.

silica is the combination of oxygen and silicon

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6
Q

List the types of volcanic rocks, ranging from low silica to high silica

A
  1. Basalt (lowest silica)
  2. andesite
  3. dacite
  4. rhyolite (highest silica)
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7
Q

What is Viscocity

A

The resistance to flow

magma viscocity is determined by silica content and temperature

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8
Q

Characteristics of magma with high silica content include?

A

cooler, more vicious, more gases

high silica magma tend to produce eruptions that explode

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9
Q

List traits of magma with low silica content

A

hotter, less vicious, fewer gases

low silica magma tend to produce eruptions that flow

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10
Q

What are the four different types of volcanoes

A

Shield, composite, volcanic dome, cinder cone

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11
Q

How are volcanoes classified?

A

Though their shape, appearance, and style of eruptions

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12
Q

What are shield volcanoes

A

the largest volcanoes on earth

  • shaped as broad arcs built from lava
  • eruptions are non explosive
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13
Q

What is tephra?

A

Fragmented materials blown out during an eruption

- some shield volcano eruptions contain tephra

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14
Q

Accumulations of tephra are referred to as?

A

Pyroclastic deposits

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15
Q

Compacted pyroclastic deposits are called?

A

Pyroclastic rock

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16
Q

Shield volcanoes are common in what places?

A

Hawaii, Iceland and around the Indian ocean

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17
Q

describe composite volcano eruptions

A

eruptions are more dangerous and explosive but less frequent than shield volcanoes

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18
Q

Describe volcanic domes

A

These volcanoes contain highly viscous rhyolite magma

- steep sided mounts that form around vents

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19
Q

What is Cinder Cone Volcanoes

A

Relatively small volcanoes composed of small pieces of tephra

  • round to oval shaped and typically contain a crater at the top
  • found in Mexico
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20
Q

What is Maars

A

A circular volcanic crater produced by an explosive eruption and filled with water

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21
Q

How are Maars caused?

A

Maars are caused by groundwater encountering magma creating an explosion

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22
Q

What are Jokulhlaups?

A

Floods produced when volcanoes erupt beneath or against glaciers that melt huge quantities of ice

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23
Q

List the volcanic features

A
  • Crater
  • Volcanic Vent
  • Caldera
24
Q

What is Crater?

A
  • A depression formed by the explosion of a volcano top
25
Q

What is Volcanic Vent

A
  • an opening on the surface through which lava and pyroclastic debris erupt
26
Q

How are Caldera’s formed

A

Calderas form by the collapse of a magma chamber below a composite volcano during an explosive eruption

27
Q

Define a Geyser

A

a geyser is a groundwater that boils in an underground chamber to periodically produce a release of steam or water
- (most famous geyser in the world is the old faithful)

28
Q

What are Super Eruptions?

A

These are the products of supervolcanoes and are extremely rare events

29
Q

What are Super Eruptions?

A

These are the products of supervolcanoes and are extremely rare events
- occur when a larg

30
Q

What are Super Eruptions?

A

These are the products of supervolcanoes and are extremely rare events
- occur when a larg

31
Q

How do super eruptions occur?

A
  • They occur when a large volume of magma rises to shallow depths in the continental crust over a hot spot
  • the magma is unable to break through the crust; pressure builds until the crust can no longer contain it.
32
Q

Yellowstone National park sits on a massive caldera created from which volcano?

A

Yellowstone supervolcano

33
Q

Where are most (if not all) volcanoes restricted to in canada

A

B.C or Southern Yukon

34
Q

Which Mt provides the greatest actual risk to canada?

A

Mt. baker in Washington state

35
Q

On average, How many volcanic eruptions occur each year?

A

50 to 60

36
Q

Over the century, 400,000 people have been killed by eruptions. T OR F?

A

False, 100,000 people have been killed by eruptions over the century

37
Q

What is a Caldera?

A
  • A circular to an oval depression formed during the collapse of a volcano
  • can be up to 25km in diameter
38
Q

List effects of volcanoes

A
  • powerful eruptions can impact global climate

- ash and gases reflect solar radiation causing a cooling

39
Q

Define the term Lava Flows

A
  • These occur when magma flows out of a central crater or a fissure on the side of a volcano
40
Q

What are the two types of Lava

A

Pahoehoe Basaltic Lava

Aa basaltic lava

41
Q

What is Pahoehoe basaltic lava

A
  • low viscosity ( a few km per hour), high temperature. When hardened, it has a smooth texture
42
Q

What is Aa Basaltic lava?

A

High viscosity (a few meters per day), lower temp. When hardened, it has a blocky texture

43
Q

Define the term Lateral Blasts?

A

An eruption directed away from a volcano where materials are blown parallel to the surface

44
Q

Define the term Pyroclastic flows?

A

These are avalanches of ash, gas, and rock fragments that travel down the slopes of a volcano during an explosive eruption =

45
Q

What does the term Pyro mean? and what does the term Clatic mean?

A

Pyro means fire

clastic means broken in pieces

46
Q

Most people have been killed by pyroclastic flows than any other volcanic phenomenon. T or F

A

True

47
Q

Define the term Ash Fall?

A

Particles of ash can be carried downwind hundreds of kilometres from an eruption site

48
Q

List the hazards of ash fall

A
  • Destroys vegetation
  • contaminates surface warer
  • health hazards to people and animals
  • causes aircraft engine failure
49
Q

The type of smog that can induce asthma attacks and respiratory problems is referred to as

A

a vog

50
Q

Explain the process of a sector collapse?

A

As magma travels up the channel, the volcano can inflate and its slopes can become over steepened, leading to a collapse in the flank of a volcano

51
Q

Define the term Lahars?

A

Large amounts of material that become saturated with water and move downslope. It is an Indonesian word

52
Q

What is another term of lahars

A

Mudflows

53
Q

List some Natural Service Functions that are derived from volcanoes?

A
  • Ancient volcanoes provided the gases that currently make up todays atmosphere
  • Internal heat from volcanoes can produce renewable geothermal energy
  • Volcanic soils are good for agriculture due to their porous, well drained, and nutritious feel
  • volcanic landscapes attract tourism and recreation
  • eruptions have created new land (Hawaii, Iceland)
54
Q

What is an eruption forecast?

A

An eruption forecast is a statement of the probability that a volcano will erupt within a defined time

55
Q

An eruption forecast is based on info provided by what?

A
    1. Monitoring seismic activity
      1. Thermal and hydrologic monitoring
      2. Land surface monitoring
      3. monitoring volcanic gas emissions
      4. understanding local geologic history

Geo of toursim (5 decks)

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