3.1 Elementary plate tectonics

Question 1

Benioff zone

Answer 1

Narrow zone of deep earthquake foci at a subduction zone.

Question 2

Continental crust

Answer 2

Part of the Earth’s crust that forms the continents.

Question 3

Continental drift

Answer 3

Theory that the continents have drifted across the surface of the globe.

Question 4

Convergent plate boundaries

Answer 4

Margins where plates are moving towards each other.

Question 5

Core

Answer 5

Central part of the Earth below 2900 km from the surface.

Question 6

Crust

Answer 6

Outermost layer of the Earth. It may be divided into continental and oceanic.

Question 7

Divergent plate boundaries

Answer 7

Plate boundaries in which the plates are moving apart.

Question 8

Hotspot

Answer 8

Relatively small area where magma rises through a continental or ocean plate. As the plate moves across a hot spot a chain of volcanoes may be formed

Question 9

Island arcs

Answer 9

Chains of volcanic islands on the continental side of an ocean trench. Associated with a subduction zone.

Question 10

Lava

Answer 10

Molten magma that reached the Earth’s surface

Question 11

Lithosphere

Answer 11

Outermost layer of the Earth, comprising the crust and part of the mantle.

Question 12

Magma

Answer 12

Molten rock within the Earth. When it reaches the surface it is called lava.

Question 13

Mercalli Scale

Answer 13

Scale of earthquake intensity based of descriptive data.

Question 14

Mid-ocean ridges

Answer 14

Lines of mainly mountains formed when two ocean plates are separating

Question 15

Oceanic crust

Answer 15

Part of the crust underlying the oceans.

Question 16

Oceanic trenches

Answer 16

Arc-shaped depressions formed at subduction zones where one tectonic plate plunges a less dense continental one.

Question 17

Oceanic ridges

Answer 17

Largest feature of the ocean floor. They are essentially a linear belt of submarine mountains.

Question 18

Ritcher scale

Answer 18

Open ended scale to record the magnitude of earthquakes.

Question 19

Sea-floor spreading

Answer 19

Where ocean floors grow as plates move apart at constructive margins.

Question 20

Shield

Answer 20

Continental area that has not been deformed since Pre-Cambrian times.

Question 21

Subduction zone

Answer 21

Area where one plate sides beneath another, where earthquakes occur.