Volcanoes

Question 1

What is vulcanicity?

Answer 1

The process of gases and molten rock moving from mantle to crust, or mantle to surface

Question 2

Difference between magma and lava:

Answer 2

Magma: Molten rock from upper layer of mantle
Lava: When magma reaches surface and loses its gas

Question 3

What factors affect the formation of landforms via volcanoes?

Answer 3

Location of eruption
Lava type
Type of material (ash/pumice etc..)
Chemistry (make up/temp)
Viscosity
Explosive/effusive

Question 4

What are explosive volcanoes also known as and what are they made up of?

Answer 4

Composite volcano
Strato volcano
Made up of layers of ash and acid lava

Question 5

Describe an explosive eruption

Answer 5

Acid magma solidifies as it does not flow easily
Acts as a plug to prevent magma rising
Pressure eventually released and blows off top of volcano (creates caldera)

Question 6

What type of plate boundaries do explosive occur at?

Answer 6

Convergent plate boundaries

Question 7

What type of lava is present at explosive eruptions?

And what are the characteristics of the lava

Answer 7

Rhyolite (more acidic)
Andesite (less acidic)
Lava has high viscosity and low temperature at eruption point

Question 8

What type of material is erupted?

Answer 8

Ash, gas, dust, lava bombs, tephra

Question 9

Define intrusion

Answer 9

Movement of magma from Earth’s crust intro spaces in overlying strata

Question 10

What are igneous sills and igneous dykes?

Answer 10

Sills: Intrusion of magma under surface that moves between strata layers
Dykes: Same as sills but magma moves across strata layers

Question 11

What are effusive eruptions also known as?

Answer 11

Shield volcanoes found at constructive plate margins

Question 12

What is a lava plateau

Answer 12

Basaltic magma erupts from multiple fissure -> vast areas covered by free flowing lava

Question 13

Lava type and characteristics at effusive eruptions (shield):

Answer 13

Basaltic

Low viscosity, high temperature at eruption

Question 14

Materials erupted at effusive eruptions

Answer 14

Gas and lava flows

Question 15

List the different types of volcanic eruptions:

Answer 15

Plinian
Vesuvian
Hawaiian
Vulcanian
Strombolian
Icelandic Lava

Question 16

Plinian eruption main characteristics

Answer 16

Biggest eruption

Violent eruption creates gas clouds

Question 17

Vesuvian eruption main characteristics

Answer 17

Almost as powerful as Plinian

Violent, gas clouds produced

Question 18

Hawaiian eruption main characteristics

Answer 18

Runny lava travels down sides

Question 19

Vulcanian eruption main characteristics

Answer 19

Viscous lava solidifies quickly after explosion

Question 20

Strombolian eruption main characteristics

Answer 20

Frequent gas explosions

White cloud emitted during eruption

Question 21

Icelandic Lava eruption main characteristics

Answer 21

Least explosive

Persistent fissure eruptions

Question 22

How can eruptions occur that are not at plate boundaries (with example)?

Answer 22

Eruptions at hotspot
Magma plume rises from mantle and erupts at surface
E.g Hawaiian Chain of Volcanic Islands

Question 23

Define supervolcano (with example)

Answer 23

A volcano that erupts more than 1000 km^3 of material in a single event
75km (diameter) caldera

Question 24

Give some info about Yellowstone

Answer 24

75km (diameter) caldera
Longer recurrence time
Last eruption spread over all of west of North America

Question 25

How are volcanoes measured?

Answer 25

Volcanic Explosivity Index (VEI)

Question 26

What does VEI combine?

Answer 26

Magnitude and intensity

Scale from 0-8

Question 27

What are some of the hazards created by volcanic eruptions?

Answer 27

Lava flows
Pyroclastic flows
Gas emissions
Tephra (volcanic bombs)
Lahars
Tsunamis