Volcano

Question 1

Most volcanic activity is associated with ______

Answer 1

plate boundaries

Question 2

Volcanoes are associated with which types of boundaries?

Answer 2

Convergent, divergent

Question 3

Volcanoes not on plate boundaries are on what?

Answer 3

Hot spots

Question 4

Spreading ridges are _____

Answer 4

Volcanoes

Question 5

Divergent boundaries:

Answer 5

Crust being pulled apart, mid-ocean ridges and continental rift

Question 6

Subduction zones:

Answer 6

Ocean crust being recycled into mantle

Question 7

Hotspots:

Answer 7

Oddballs, volcanoes not associated with plate boundaries

Question 8

What kinds of plate boundaries are in the northern triangle?

Answer 8

Transform, convergent

Question 9

What do plate tectonics control?

Answer 9

Where and how rocks are melted to create magma

Question 10

The type of magma produced controls…

Answer 10

what volcanic material erupts at the surface

Question 11

Hazards associated with a volcano is directly related to -

Answer 11

the properties of the volcanic material that comes out of it

Question 12

Divergent plate boundaries separate what?

Answer 12

Two lithospheric plates

Question 13

What fills the space created from the lithospheric plates separating?

Answer 13

Asthenosphere - fluid like mantle material

Question 14

What happens in the asthenospheric mantle?

Answer 14

The mantle melts to create magma

Question 15

Why does melting occur at divergent plate boundaries?

Answer 15

Because pressure on the hot mantle rock is decreased

Question 16

Volcanic rock is typically…

Answer 16

Basalt

Question 17

What is basalt?

Answer 17

A fluid, low silica, lava

Question 18

Magma has little ____ and ____ in it

Answer 18

H2O, gas

Question 19

When basalt erupts from mid-ocean ridges what forms?

Answer 19

Pillow basalts on the sea floor

Question 20

What occurs when there are eruptions on land?

Answer 20

Cinder cones, basalt lava flows

Question 21

Mid-ocean ridge eruptions are usually from…

Answer 21

fissures

Question 22

Where does magma come from that is from rift volcanoes?

Answer 22

Straight from the mantle

Question 23

Mantle rocks are only ____ melted

Answer 23

partially

Question 24

___% of original mantle rock melts to form basalt magma

Answer 24

10

Question 25

Minerals with ___ silica melt at lower temps

Answer 25

high

Question 26

When a rock partially melts, the resulting magma has a ____ silica content than the parent rock

Answer 26

higher

Question 27

What also changes when a rock partially melts?

Answer 27

The amount of other elements

Question 28

What controls the physical properties of magma?

Answer 28

Chemical composition

Question 29

Viscosity

Answer 29

Resistance to flow

Question 30

What happens to silicate ions in vicious magma?

Answer 30

They stick to each other to form chains

Question 31

What ions want to form with silicon atoms?

Answer 31

Oxygen

Question 32

What breaks the silicon-oxygen chain?

Answer 32

H2O

Question 33

Viscosity of magma is dependent on…

Answer 33

SiO2 content

Question 34

Most magmas start off as…

Answer 34

Basalt

Question 35

How can magma properties change?

Answer 35

When it travels through existing crust during eruption

Question 36

What happens with magma at mid-ocean ridges?

Answer 36

It makes new crust, has little to no interactions and results in basalt

Question 37

What happens with magma during continental rifting?

Answer 37

larger potential for interaction/mixing, andesite/rhyolite may erupt first followed by basalt

Question 38

Rifting results in ____ ____ of mantle rock

Answer 38

decompression melting

Question 39

What does rifting produce?

Answer 39

Hot, low silica magma

Question 40

What kind of magma comes from rifting?

Answer 40

Magma is fluid (low viscosity) and usually has low volatile (water and gas) content

Question 41

How can volcanic material be modified?

Answer 41

Interaction with overlying crust