Topic 1: Tectonic Processes and Hazards

Question 1

natural hazard

Answer 1

a naturally occurring process or event that has the potential to affect people

Question 2

natural disaster

Answer 2

a major natural hazard that causes significant social, environmental and economic damage

when a natural hazard strikes a vulnerable population that can’t cope using its own resources

Question 3

vulnerability

Answer 3

the ability to anticipate, cope with, resist and recover from a natural hazard

greater scale natural hazard = more vulnerable population = greater disaster

Question 4

plate-tectonic theory: mantle convection

Answer 4

• less accepted argument
• heat produced by decay of radioactive elements in Earth’s core
• heats lower mantle, creating convection currents (of hot, liquid magma)
• currents move in circles in asthenosphere, causing plates to move

Question 5

plate-tectonic theory: slab pull

Answer 5

• newly formed oceanic crust at mid-ocean ridges becomes denser and thicker as it cools
• sinks into mantle under its own weight, pulling rest of plate further down with it

Question 6

plate-tectonic theory: subduction

Answer 6

• two oceanic plates (or oceanic/continental) move towards each other
• one slides under the other into mantle
• melts in a subduction zone

Question 7

plate-tectonic theory: seafloor spreading

Answer 7

• huge mid-ocean ridges form in the middle of oceans when hot magma is forced up from the asthenosphere and hardens
• forms new oceanic crust
• new crust pushes plates apart

Question 8

structure of the Earth

Answer 8

core:
inner core →
outer core →

mantle:
lower mantle →
upper mantle →

crust:

Question 9

lithosphere

Answer 9

crust + upper mantle

Question 10

palaeomagnetism

Answer 10

the study of past changes in the Earth’s magnetic field (determined from rocks, sediment, or archaeological records)

Question 11

evidence for seafloor spreading

Answer 11

• studies of palaeomagnetism in the 1950s
• Earth’s magnetic fields change direction (north and south poles swap) approx. every 400,000 years
• when lava cools and becomes rock, minerals in the rock line up with Earth’s magnetic direction (polarity) at the time
• same pattern of magnetic direction found on either side of mid-ocean ridges
• therefore new rock is being formed at the same time on both sides

Question 12

asthenosphere

Answer 12

part of the mantle below the lithosphere, where the rock is semi-molten

Question 13

asthenosphere

Answer 13

part of the mantle below the lithosphere, where the rock is semi-molten

Question 14

Benioff zone

Answer 14

the area where friction is created between colliding tectonic plates, resulting in intermediate and deep earthquakes

Question 15

convection currents

Answer 15

hot, liquid magma currents moving in the asthenosphere

Question 16

crustal fracturing

Answer 16

when energy released during an earthquake causes the Earth’s crust to crack

Question 17

epicentre

Answer 17

the point on the Earth’s surface directly above the focus of an earthquake

Question 18

focus

Answer 18

the point inside the Earth’s crust from which the pressure is released when an earthquake occurs

Question 19

hazard-management cycle

Answer 19

a theoretical model of hazard management as a continuous four-stage cycle involving mitigation, preparation, response and recovery

Question 20

hot spot

Answer 20

points within the middle of a tectonic plate where plumes of hot magma rise and erupt

Question 21

intra-plate earthquakes

Answer 21

earthquakes which occur far from plate margins

Question 22

intra-plate earthquakes

Answer 22

earthquakes which occur far from plate margins

Question 23

L waves

Answer 23

the slowest seismic waves, which focus all their energy on the Earth’s surface

Question 24

liquefaction

Answer 24

when the violent shaking during an earthquake causes surface rocks to lose strength and become more liquid than solid

Question 25

lithosphere

Answer 25

the solid layer, made from the crust and upper mantle, from which tectonic plates are formed

Question 26

mitigation

Answer 26

action to reduce the impacts of an event

Question 27

multiple-hazard zone

Answer 27

an area that is at risk from multiple natural hazards

Question 28

P waves

Answer 28

the fastest seismic waves which travel through both solids and liquids

Question 29

Park model (hazard-response curve)

Answer 29

shows how a country or region might respond after a hazard event

Question 30

pressure and release (PAR) model

Answer 30

a tool used to work out how vulnerable a country is to hazards

Question 31

S waves

Answer 31

seismic waves which only travel through solids and move with a sideways motion

Question 32

slab pull

Answer 32

when newly formed oceanic crust sinks into the mantle, pulling the rest of the plate further down with it

Question 33

subduction zone

Answer 33

the area in the mantle where a tectonic plate melts

Question 34

transform fault

Answer 34

a fault created on a large scale when two plates slide past each other