Key Terms

Question 1

Magma

Answer 1

• molten rock within Earth
• when reaches surface = lava

Question 2

Hotspot

Answer 2

• small area where magma rises through a C or O plate
• as plate moves across hotspot, chain of volcanoes may form

Question 3

Lava

Answer 3

• molten magma that’s reached Earth’s surface
• may be solid or liquid

Question 4

Subduction zone

Answer 4

• area where 1 plate slides beneath another
• zones of earthquakes + melting

Question 5

Benioff zone

Answer 5

• narrow zone of deep earthquake foci at a subduction zone

Question 6

Ocean trenches

Answer 6

• long, narrow depressions in ocean floor, w depths up to 11,000m

Question 7

Trench outer rise

Answer 7

• a low bulge on ocean floor ahead of a subduction zone

Question 8

Outer slope (of an ocean trench)

Answer 8

• associated w island arcs
• generally gentle but broken by faults as plate bends

Question 9

Inner slope (of an ocean trench)

Answer 9

• associated w island arcs
• steeper + contains fragments of subducting plate

Question 10

Subduction complex (accretionary prisms)

Answer 10

• part of descending plate + may form O islands

Question 11

Island arc

Answer 11

• line of islands parallel to an ocean trench
• typically 150-200km from trench, on over-riding plate