Volcanoes

Question 1

Crater:

Answer 1

A basin-like rimmed structure at top or on flanks of a volcanic cone

Question 2

Vent:

Answer 2

Opening at Earth’s surface through which volcanic material is extruded

Question 3

Magma Chamber:

Answer 3

A reservoir of magma in the shallow part of the lithosphere

Question 4

Magma Formation-Rift at mid-ocean ridge:

Answer 4

Decrease in pressure lowers melting temperature of materials in the asthenosphere

Question 5

Magma Formation-Asthenosphere at a hot spot:

Answer 5

Temperature increase can cause materials to melt

Question 6

Magma Formation-Asthenosphere at subduction boundaries:

Answer 6

Increase in amount of water in the asthenosphere can lower melting temperature of materials there

Question 7

What controls the magma type and eruption style?

Answer 7

The viscosity of the magma

Question 8

What effects viscosity?

Answer 8

Temperature of magma:
-hotter, lower viscosity, more fluid

Composition of magma (amount of silica):
-more silica, higher viscosity, more resistant to flow

Question 9

What makes magma/lava erupt?

Answer 9

• Magma is a liquid, less dense than surrounding material

- Gases within magma rise to surface

Question 10

Low viscosity lava:

Answer 10

Gases easily rise and are gently released

Question 11

High viscosity lava:

Answer 11

Gases build up resulting in explosive eruptions

Question 12

Basaltic Magma:

• Silica Content
• Gas Content
• Viscosity
• Type of Eruption
• Melting Temperature
• Location
• Example

Answer 12

• Less than or equal to 50%
• Least
• Least
• Rarely explosive
• Highest
• Rifts, oceanic hotspots
• Kilauea

Question 13

Andesitic Magma:

• Silica Content
• Gas Content
• Viscosity
• Type of Eruption
• Melting Temperature
• Location
• Example

Answer 13

• 60%
• Intermediate
• Intermediate
• Sometimes explosive
• Intermediate
• Subduction boundaries
• Mountain St. Helens

Question 14

Rhyolitic Magma:

• Silica Content
• Gas Content
• Viscosity
• Type of Eruption
• Melting Temperature
• Location
• Example

Answer 14

• 70%
• Most
• Most
• Usually explosive
• Lowest
• Continental hotspots
• Yellowstone

Question 15

What is a volcano?

Answer 15

An opening in Earth’s crust through which molten rock, gases and ash erupt

Question 16

Types of magma:

Answer 16

• Basaltic
• Andesitic
• Rhyolitic

Question 17

Lava:

Answer 17

Liquid molten rock

Question 18

Pahoehoe:

Answer 18

Ropelike lava

Question 19

Aa:

Answer 19

Crumbly lava

Question 20

Pillow lava:

Answer 20

Thought to have formed under water

Question 21

Solid pyroclastic materials:

Answer 21

• Ash
• Cinders
• Lapilli
• Blocks/Bombs
• Pyroclastic flow

Question 22

Sizes-
Ash:
Cinders:
Lapilli:
Blocks/Bombs:

Answer 22

• Microscopic solids
• Pea sized
• Walnut size
• Football size or bigger

Question 23

Pyroclastic Flow:

Answer 23

Avalanche of burning ash

Question 24

Volcano types:

Answer 24

• Cinder cone
• Composite (stratovolcano)
• Shield

Question 25

Cinder cone:

Answer 25

- Steep-sided, formed by explosive eruption of cinders - Small height, short lived - Sunset crater, Arizona

Question 26

Composite:

Answer 26

Steep-sided, built by lava flows and pyroclastic deposits alternating layers, andesitic, most dangerous Osorno volcano in the Chilean Andes

Question 27

Shield Volcano:

Answer 27

Gentle slope, resembles a warriors shield, quiet eruptions of fluid lava flows (basaltic), largest land forms on earth, Mauna Loa

Question 28

Caldera:

Answer 28

Crater-shaped basin formed after the top of a volcano collapses Crater Lake, Oregon

Question 29

Lahars:

Answer 29

Volcanic mudflow often formed when hot ash mixes with water from melted snow and ice or a crater lake