TECTONICS

Question 1

where are tectonic hazards distributed?

Answer 1

along tectonic plate boundaries or at faults/weaknesses in rocks

Question 2

what are the three types of plate boundary?

Answer 2

• divergent
• convergent
• transverse

Question 3

how are intra-plate earthquakes causes?

Answer 3

triggered by stress reactivating ancient fault lines or zones of weakness deep within the crust, caused by forces from distant plate boundaries, mantle convection –> causes a release of energy which its the earthquake

Question 4

how do hot spots create volcanoes?

Answer 4

• Mantle Plume: A deep-seated plume of unusually hot, buoyant magma originates far below the Earth’s crust, potentially from the core-mantle boundary.
• Melting the Crust: This plume rises, heating the overlying mantle and crust. - The intense heat causes the rock at the base of the lithosphere (Earth’s crust and upper mantle) to melt, forming magma.
• Magma Eruption: The magma, less dense than surrounding rock, rises and pushes through weaknesses or cracks in the tectonic plate above.
• Volcano Formation: When magma erupts onto the surface (either ocean floor or land), it cools and solidifies, building up volcanic structures.
• Plate Movement Creates Chains: The key is that the mantle plume is relatively stationary, while the tectonic plate above it moves. As the plate drifts, it carries the volcano away from the heat source, making it extinct, and a new volcano begins to form over the hotspot, creating a volcanic chain

Question 5

give an example of a chain of volcanic islands caused by a hot spots

Answer 5

The Haiwian Islands

Question 6

what is the plate tectonics theory?

Answer 6

the scientific theory describing the large scale movement of tectonic plates over the last 100s of millions of years

Question 7

what are the theories behind plate movement?

Answer 7

• convection currents
• slab pull
• ridge push

Question 8

explain how convection currents were though to move tectonic plates

Answer 8

• lower mantle would be heated by the decay of radioactive elements, creating a convection current
• these hot magma currents would circulate though the aesthenoshpehe causing the plates to move

Question 9

explain how slab pull is though to move tectonic plates

Answer 9

at subduction zones where old, cold, dense oceanic plates sink into the mantle due to gravity, they pull the rest of the plate behind it like a heavy chain, causing the plate to move in that direction

Question 10

explain how ridge push is though to move tectonic plates

Answer 10

• Magma Upwelling: At mid-ocean ridges (constructive plate boundaries), hot magma rises from the mantle, cools, and solidifies to form new oceanic lithosphere Elevation & - Cooling: This new crust is initially warm and sits at a higher elevation, forming underwater mountain ranges (the ridge). As it moves away from the ridge, it cools, becomes thicker, and significantly denser.
• Slope Formation: The difference in density and age creates a slope, with the lithosphere at the ridge being higher than the surrounding ocean floor.
• Gravitational Sliding: Gravity acts on this elevated, dense plate, causing it to slide or “push” down the sloping flanks of the ridge.
• Plate Movement: This gravitational sliding pushes the entire plate further away from the ridge crest, moving the plate

Question 11

what does ridge push cause?

Answer 11

sea floor spreading

Question 12

what proof do we have of sea floor spreading?

Answer 12

paleomanetism - Magma & Magnetic Minerals: As magma rises at mid-ocean ridges (divergent plate boundaries), it cools, and magnetic minerals (like magnetite) align with Earth’s prevailing magnetic field.
- Polarity Reversals: The Earth’s magnetic field periodically reverses its polarity (North becomes South and vice versa).
- “Magnetic Stripes”: Each time the field reverses, new crust forms with a different magnetic signature, creating alternating bands (stripes) of normal and reversed polarity.
- Symmetry & Spreading: These stripes are found in perfect mirror images on either side of the ridge, with the youngest rocks at the centre and progressively older rocks moving outwards.

Question 13

which 4 physical processes influence the type of volcanic eruption that occurs and how?

Answer 13

1. Magma composition — silica‑rich vs silica‑poor magma affects viscosity.
2. Viscosity — thick magma traps gases → explosive eruptions; runny magma lets gases escape → effusive eruptions.
3. Gas content — more dissolved gases = more explosive potential.
4. Tectonic setting — constructive, destructive, and hotspot settings produce different magma types.

Question 14

describe an effusive eruption

Answer 14

— runny basaltic magma (e.g., Iceland) → low magnitude, lava flows.

Question 15

describe an explosive eruption

Answer 15

viscous andesitic/rhyolitic magma (e.g., subduction zones) → high magnitude, ash, pyroclastic flows.

Question 16

which physical processes control earthquake characteristics?

Answer 16

Plate movement type — subduction, collision, transform boundaries create different stress patterns.
Rock type + rigidity — affects how much strain builds before release.
Depth of focus — shallow, intermediate, deep earthquakes occur along the descending slab.

Question 17

how does earthquake focus depth affect the magnitude?

Answer 17

– Shallow-focus earthquakes — 0–70 km; most destructive because energy is released near the surface.
– Intermediate-focus earthquakes — 70–300 km; occur further down the Benioff zone.
– Deep-focus earthquakes — 300–700 km; less damaging at the surface but can be high magnitude.

Question 18

what and where is the Benioff zone?

Answer 18

a key concept at destructive plate boundaries, representing an inclined zone where deep, powerful earthquakes occur as a dense oceanic plate subducts (sinks) beneath a less dense plate

Question 19

where is an earthquakes hypo centre?

Answer 19

directly beneath the epicentre, along the fault line

Question 20

where is an earthquakes epicentre?

Answer 20

directly above the hypo centre, on the crust surface

Question 21

which type of seismic wave is the fastest?

Answer 21

P waves

Question 22

which type of seismic wave is the slowest?

Answer 22

L waves

Question 23

which seismic wave can travel through both solid and liquid?

Answer 23

P waves

Question 24

which seismic wave can only travel through solids?

Answer 24

S waves

Question 25

which seismic wave can only travel through the crust/along the earths surface?

Answer 25

L waves

Question 26

what can seismic waves cause?

Answer 26

crust fracturing ground shaking soil liquefaction --> land slides

Question 27

which seismic wave arguably has the greatest impact and why?

Answer 27

L waves because they are confined to the crust and therefore closer to humanity

Question 28

how does soil liquefaction happen?

Answer 28

Seismic waves trigger soil liquefaction in water-saturated, loose, sandy soils by causing rapid, cyclic shaking that compacts the grains, trapping water and dramatically increasing pore water pressure; -- this pressure eventually exceeds the soil's strength, making the soil behave like a liquid and lose its ability to support structures. -- The shaking disrupts the soil's internal structure, allowing water to fill the spaces, and when shaken intensely and rapidly enough, the soil loses its strength and flows like quicksand until shaking stops.

Question 29

what can soil liquefaction cause?

Answer 29

landslides

Question 30

what four primary hazards can volcanic eruptions cause

Answer 30

- ash fall - gas eruptions - lava flows - pyroclastic flows

Question 31

can volcanoes and earthquakes both have secondary impacts?

Answer 31

yes

Question 32

how are tsunamis produced?

Answer 32

by sub marine earthquakes

Question 33

how do sub marine earthquakes cause tsunamis?

Answer 33

- a plate shift abruptly at a subduction zone, releasing energy and displacing water columns of water - the displacement of water generates waves which move out/away in all directions - as waves enter shallow water they compress, their speed slows and they build in height

Question 34

describe shoaling

Answer 34

- As waves move into shallower areas (where depth < half wavelength), their base drags on the seabed, reducing their speed. - To conserve energy, the waves get closer together and (shorter wavelength), their crests rise (increased height/amplitude) - This "squeezing" and height increase leads to taller, steeper waves

Question 35

define a natural hazard

Answer 35

a powerful, naturally occurring event (like an earthquake, hurricane, or flood) that threatens people, property, and the environment

Question 36

define a natural disaster

Answer 36

a natural event such as a flood, earthquake, or hurricane that causes great damage or loss of life.

Question 37

state the hazard risk equation

Answer 37

risk = hazard x vulnerability -------------------------------- ability to cope

Question 38

what does the pressure and release model show?

Answer 38

how disasters happen when vulnerability + hazard combine

Question 39

what does the PAR framework aim to to?

Answer 39

To explain why some places suffer worse impacts from the same hazard.

Question 40

which frame work attempts to explain why some places suffer worse impacts from the same hazard?

Answer 40

the pressure and release model

Question 41

what are the five sections within the PAR model

Answer 41

1. Root causes Deep‑set political, economic and social factors that create vulnerability. 2. Dynamic pressures Processes that turn root causes into unsafe conditions (e.g., rapid urbanisation). 3. Unsafe conditions The immediate, local vulnerabilities that make people exposed to hazards. 4. Hazard event The physical trigger (earthquake, volcano, tsunami, etc.). 5. Disaster = hazard + vulnerability A disaster only occurs when a hazard meets high vulnerability.

Question 42

what does the PAR model suggest about vulnerability?

Answer 42

Vulnerability is socially constructed Disasters aren’t “natural” — human systems shape the impact.

Question 43

how is the PAR model progressive?

Answer 43

Vulnerability builds up over time through linked processes.

Question 44

how does the PAR model suggest vulnerability can be reduced?

Answer 44

Addressing root causes and dynamic pressures lowers vulnerability.

Question 45

which country examples can the PAR model be applied to and how?

Answer 45

Haiti 2010 was catastrophic but Japan 2011 was not. Haiti 2010 PAR analysis Root causes: debt, corruption, poverty → dynamic pressures: lack of planning → unsafe conditions: weak buildings → hazard: M7 quake. Japan 2011 PAR analysis Strong governance + preparedness reduced vulnerability despite a huge hazard. M9

Question 46

which scales can be used to measure earthquakes, and what do they measure?

Answer 46

- mercalli scale - observable damage - righter scale - amplitude - moment magnitude scale - total energy

Question 47

which scale can be used to measure volcanic eruptions, and what does it measure?

Answer 47

- the volcanic explosively scale - explosiveness

Question 48

what can be used to compare the characteristics of earthquakes, volcanic eruptions, and tsunamis?

Answer 48

a hazard profile

Question 49

what are three things that a hazard profile compares?

Answer 49

- speed of onset - magnitude - duration

Question 50

what does the deggs model show?

Answer 50

how a natural event becomes a natural hazard when it affects people

Question 51

which model shows how a natural event becomes a natural hazard when it affects people?

Answer 51

deggs model

Question 52

describe the deggs model

Answer 52

overlapping circles - the intersection represents the scale of the disaster

Question 53

how can the parks model be used to show the impacts of tectonic events in countries of varying development?

Answer 53

Shows how development level shapes vulnerability and resilience - smaller curve = less damage - steeper = quicker recovery - return to or exceeding of normality

Question 54

which model can be used to show how development level shapes vulnerability and resilience

Answer 54

the parks model

Question 55

why has there been an increased frequency of tectonic hazards since the 1960s?

Answer 55

- increased population - better detection through technology - increased populations living in at risk areas

Question 56

why has there been a decrease deaths due to tectonic hazards since the 1960s?

Answer 56

- improved prediction, preparation and prevention - better medical care - increasing global wealth

Question 57

why has there been an increased cost of tectonic hazards since the 1960s?

Answer 57

- more to break - more expensive infrastructure in risk areas better technology expensive to replace

Question 58

which case studies can be used as examples of mega disasters with regional/global significance in terms of economic and human impacts?

Answer 58

- 2011 Japan tsunami - 2004 asian tsunami - 2010 Iceland eruption

Question 59

what is a multi hazard zone?

Answer 59

a geographical area prone to two or more natural hazards

Question 60

give an example of a multi hazard zone

Answer 60

the phillipenes - hydrometeorological hazard

Question 61

why can tectonic disasters be difficult to predict?

Answer 61

- earthquakes often strike suddenly with little warning, though scientists monitor seismic activity and historical data for long-term probabilities - tsunamis can be easier to predict as the earthquake gives warning - although proximity to society determines how prepared we can be - volcanoes on the other hand offer multiple warning signs like gas emissions, ground deformation, and small tremors, indicating magma movement -- however, advancing technology makes it easier for us to detect and predict tectonic disasters

Question 62

name the four sections of the hazard management cycle

Answer 62

- mitigation - preparation - response - recovery

Question 63

why is mitigation important in managing tectonic hazards?

Answer 63

- helps to minimise their effects/reduce their impacts

Question 64

what is the main aim of mitigation in managing tectonic hazards?

Answer 64

reducing the loss of life and property

Question 65

what three actions are examples of hazard mitigation?

Answer 65

- land zoning and and use planning - developing and enforcing building codes - building protective structures like sea walls

Question 66

give an example of how better building regulations helped to mitigate the impacts of a tectonic hazard

Answer 66

Japan: - 1995 Kobe Earthquake (Mw 6.9) = over 200,000 buildings damaged or destroyed - over 120,000 - BUT the earthquake was a 9 on the magnitude scale

Question 67

why is preparedness important in managing tectonic hazards?

Answer 67

- how people prepare for an incoming hazard - facilitates the response and recovery phases (makes them easier) - minimises loss of life and property

Question 68

what three actions are examples of hazard preparedness?

Answer 68

- creating evacuation routes - stockpiling aid equipment and supplies - e.g. typhoon Haiyan - would not have had to wait 3 days for supplies - developing early warning systems

Question 69

why is response important in managing tectonic hazards?

Answer 69

- how people cope with the disaster - reduces loss of life and economic losses

Question 70

what 4 actions are examples of hazard response?

Answer 70

- search and rescue teams - evacuations were needed - ensuring critical services continue - restoring critical infrastructure

Question 71

why is recovery important in managing tectonic hazards?

Answer 71

- aids better preparedness for the next hazard event

Question 72

what 4 actions are examples of short term hazard recovery?

Answer 72

- proving food and power - organising financial assistance - proving essential health and safety services - re-establishing transport routes

Question 73

what 2 actions are examples of long term hazard recovery?

Answer 73

- rebuilding homes and infrastructure - reopening businesses and schools

Question 74

which model can be used to compare the response of hazards in different stages of development?

Answer 74

the parks model

Question 75

which strategies can be used to modify the hazard event?

Answer 75

- and use zoning - lava flow diversion e.g mt st helens - engineering defences - resistant building designs e.g. earthquake resistant buildings in Japan

Question 76

what strategies has Japan implemented to improve its prediction, education, and community preparedness for hazard events?

Answer 76

- earthquake drills in schools - 4,235 land‑based seismometers used by the Japan Meteorological Agency (JMA) to detect earthquakes - GIS mapping + satellite communication to transmit data for easy warnings - used in 2004 - data was transmitted every 15s

Question 77

what is GIS mapping used for?

Answer 77

to identify the extent of destruction, and plan emergency routes

Question 78

which strategies can be used to modify the vulnerability and resilience of a hazard event? give an example for one of these.

Answer 78

- hi-tech monitoring - prediction - Indian Ocean tsunami warning system set up in 2006 - eduction - community preparedness

Question 79

which strategies can be used to modify loss during/after a hazard event? give an example for one of these.

Answer 79

- emergency aid and insurance - short term aid and insurance - long term aid and insurance

Question 80

how did the Nepal 2015 earthquake use crisis mapping?

Answer 80

after the quake volunteers went round on bicycles and collected data to show areas of vulnerability e.g. where most roads were destroyed

Question 81

how can computers be used to mitigate hazards?

Answer 81

an build model scenarios to compare, then develop the best strategies to reduce impacts

Question 82

why is community preparedness important in hazard mitigation?

Answer 82

- vulnerable people can be identified - evacuation drills first aid course can be provided

Question 83

give an example of how local knowledge is important in hazard mitigation?

Answer 83

2004 indian ocean tsunami = Moken tribe in thailand noticed unusual movements in the bay of bengal + ordered an evacuation to hilltops: only 1 out of 200 died

Question 84

why are NGOs important in hazard aid and insurance?

Answer 84

- offer aid when governments struggle to respond - help with search and rescue, and reconstruction plans

Question 85

give an example of how NGOs helped during a hazard event

Answer 85

2005 pakistan earthquake: provided 500,000 tents and safe water for 70,000 people

Question 86

how are local communities helpful in hazard events?

Answer 86

- crucial in immediate search and rescue - know who needs the most help - often involved in long term strategies

Question 87

what are the positives of insurance companies? give an example

Answer 87

provide insurance for economic losses 2023 Turkey–Syria - earthquake caused USD 280 billion in total economic losses globally in 2023 - Of this, USD 108 billion (40%) was covered by insurance

Question 88

what are the negatives of insurance companies?

Answer 88

benefits HICs but not LICs who cannot afford the insurance - unfair