Lecture 7 - volcanoes

Question 1

What are the two types of molten rocks

Answer 1

Magma and Lava rocks

Question 2

Define a Magma rock

Answer 2

It is found deep within the crust and upper mantle

Question 3

Define a Lava rock

Answer 3

flows from an erupting volcano

Question 4

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

Answer 4

False

Question 5

How are volcanic rocks named

Answer 5

Volcanic rocks are named by the number of silica present.

silica is the combination of oxygen and silicon

Question 6

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

Answer 6

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

Question 7

What is Viscocity

Answer 7

The resistance to flow

magma viscocity is determined by silica content and temperature

Question 8

Characteristics of magma with high silica content include?

Answer 8

cooler, more vicious, more gases

high silica magma tend to produce eruptions that explode

Question 9

List traits of magma with low silica content

Answer 9

hotter, less vicious, fewer gases

low silica magma tend to produce eruptions that flow

Question 10

What are the four different types of volcanoes

Answer 10

Shield, composite, volcanic dome, cinder cone

Question 11

How are volcanoes classified?

Answer 11

Though their shape, appearance, and style of eruptions

Question 12

What are shield volcanoes

Answer 12

the largest volcanoes on earth

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

Question 13

What is tephra?

Answer 13

Fragmented materials blown out during an eruption

- some shield volcano eruptions contain tephra

Question 14

Accumulations of tephra are referred to as?

Answer 14

Pyroclastic deposits

Question 15

Compacted pyroclastic deposits are called?

Answer 15

Pyroclastic rock

Question 16

Shield volcanoes are common in what places?

Answer 16

Hawaii, Iceland and around the Indian ocean

Question 17

describe composite volcano eruptions

Answer 17

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

Question 18

Describe volcanic domes

Answer 18

These volcanoes contain highly viscous rhyolite magma

- steep sided mounts that form around vents

Question 19

What is Cinder Cone Volcanoes

Answer 19

Relatively small volcanoes composed of small pieces of tephra

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

Question 20

What is Maars

Answer 20

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

Question 21

How are Maars caused?

Answer 21

Maars are caused by groundwater encountering magma creating an explosion

Question 22

What are Jokulhlaups?

Answer 22

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

Question 23

List the volcanic features

Answer 23

• Crater
• Volcanic Vent
• Caldera

Question 24

What is Crater?

Answer 24

• A depression formed by the explosion of a volcano top

Question 25

What is Volcanic Vent

Answer 25

- an opening on the surface through which lava and pyroclastic debris erupt

Question 26

How are Caldera's formed

Answer 26

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

Question 27

Define a Geyser

Answer 27

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)

Question 28

What are Super Eruptions?

Answer 28

These are the products of supervolcanoes and are extremely rare events

Question 29

What are Super Eruptions?

Answer 29

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

Question 30

What are Super Eruptions?

Answer 30

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

Question 31

How do super eruptions occur?

Answer 31

- 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.

Question 32

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

Answer 32

Yellowstone supervolcano

Question 33

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

Answer 33

B.C or Southern Yukon

Question 34

Which Mt provides the greatest actual risk to canada?

Answer 34

Mt. baker in Washington state

Question 35

On average, How many volcanic eruptions occur each year?

Answer 35

50 to 60

Question 36

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

Answer 36

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

Question 37

What is a Caldera?

Answer 37

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

Question 38

List effects of volcanoes

Answer 38

- powerful eruptions can impact global climate | - ash and gases reflect solar radiation causing a cooling

Question 39

Define the term Lava Flows

Answer 39

- These occur when magma flows out of a central crater or a fissure on the side of a volcano

Question 40

What are the two types of Lava

Answer 40

Pahoehoe Basaltic Lava | Aa basaltic lava

Question 41

What is Pahoehoe basaltic lava

Answer 41

- low viscosity ( a few km per hour), high temperature. When hardened, it has a smooth texture

Question 42

What is Aa Basaltic lava?

Answer 42

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

Question 43

Define the term Lateral Blasts?

Answer 43

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

Question 44

Define the term Pyroclastic flows?

Answer 44

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

Question 45

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

Answer 45

Pyro means fire | clastic means broken in pieces

Question 46

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

Answer 46

True

Question 47

Define the term Ash Fall?

Answer 47

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

Question 48

List the hazards of ash fall

Answer 48

- Destroys vegetation - contaminates surface warer - health hazards to people and animals - causes aircraft engine failure

Question 49

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

Answer 49

a vog

Question 50

Explain the process of a sector collapse?

Answer 50

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

Question 51

Define the term Lahars?

Answer 51

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

Question 52

What is another term of lahars

Answer 52

Mudflows

Question 53

List some Natural Service Functions that are derived from volcanoes?

Answer 53

- 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)

Question 54

What is an eruption forecast?

Answer 54

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

Question 55

An eruption forecast is based on info provided by what?

Answer 55

- 1. Monitoring seismic activity 2. Thermal and hydrologic monitoring 3. Land surface monitoring 4. monitoring volcanic gas emissions 5. understanding local geologic history