Topic 1: Tectonic processes and hazards

Question 1

How do tectonic plates move?
4 ways

Answer 1

1. Convection currents
2. Slab pull
3. Ridge Push
4. Subduction

Question 2

How do convection currents move plates?

Answer 2

Heat from decay of radioactive elements heats lower mantle - causes magma to rise, which then cools and sinks.

Question 3

How does slab pull move plates?

Answer 3

Weight of newly formed oceanic plates subducting pulls it under (causing subduction)

Question 4

How does ridge push move plates?

Answer 4

Divergent plate boundaries - hot, less dense magma rises to surface in plumes - heats surface crust causing it to fracture, so molten magma can push through. Creates oceanic ridges which slide away from each other

Question 5

How does subduction move plates?

Answer 5

Slab pull in subduction zone
More dense plate slides under the other - crust is being constantly formed and destroyed

Question 6

Compare oceanic plates to continental:

Answer 6

1. Oceanic is denser
2. Oceanic is younger

Question 7

What is palaeomagnetism and how does is prove that the seafloor is spreading?

Answer 7

Every 400,000 years, Earth’s polarity swaps (and cooling lava minerals align with polarity at the time.)
Same pattern of alternating magnetic direction on either side of oceanic ridges (suggesting new rock is being formed at the same time on either side)

Question 8

What is a convergent plate boundary?

Answer 8

Collision Zone -
2 plates push against each other - form fold mountains

Subduction zone -
Denser plate subducts under less dense plate (plate melts and magma rises as plumes)

Question 9

What is a divergent plate boundary?

Answer 9

Plates move apart
Magma is able to rise up through plates - forms new plates

Question 10

What is a conservative plate boundary?

Answer 10

Plate is not destroyed or created
Plates slide past each other- friction creates build up of pressure which is released via earthquakes

Question 11

When oceanic plate meets continental:

Answer 11

Oceanic plate is more dense so subducts under continental plate - plate melts and magma rises in plumes
Deep ocean trenches
Fold mountains
Earthquakes have deep focus

Question 12

What is a Benioff zone?

Answer 12

Area where earthquakes occur

Question 13

When oceanic meets oceanic:

Answer 13

Denser of faster plate is subjected beneath the other
Deep ocean trenches form
Underwater volcanoes
Earthquakes (Benioff zone) have deep focuses

Question 14

When continental meets continental:

Answer 14

Collision margin forms
Sediments are crumpled and forced up to form fold mountains
Earthquakes are likely to have shallow focus

Question 15

What events/ landforms occur at divergent plate boundaries?
4

Answer 15

Earthquakes
Volcanoes - shield
In oceans - Mid-ocean ridges form (magma from underwater volcanoes)
On land - Rift valleys (land between faults collapses to create a rift)

Question 16

What events/ landforms occur at Conservative plate boundaries?
3

Answer 16

Strong, shallow focus earthquakes
e.g. San Andreas fault in California USA
Create hotspots - magma rises and volcanoes form, which is then carried away as the magma current moves and is replaced (Pacific ring of fire)
Intra-plate earthquakes - weakening of mantle caused by a new magma plume or large scale convection

Question 17

What is a hotspot?

Answer 17

Form over extra-hot regions in mantle, where magma is more buoyant than surrounding rocks, so floats to surface and causes surface eruptions.

Question 18

On average, how many people die each year due to earthquakes?

Answer 18

10,000 - but this number is HUGELY variable as one major event can completely skew statistics

Question 19

How do earthquakes form?

Answer 19

1. Pressure builds up from movement of plates against one another
2. Suddenly released as seismic waves when rock fractures along cracks (faults)
3. Point inside crust is called focus/ hypocentre
   Point on ground is called epicentre

Question 20

What is more damaging for an earthquake to have?

Answer 20

Shallow hypo centre

Question 21

What are the 3 seismic wave types?

Answer 21

P waves - Fastest waves and travel through both solids and liquids (damaging)
S waves - Slower waves and only travel through solids (more damaging)
Love waves - Slowest but MOST damaging (surface waves)

Question 22

What is used to measure seismic waves?

Answer 22

Seismometer

Question 23

What motion are seismic waves travelling in?

Answer 23

P wave - backwards and fowards
S wave - Right angles
Love wave - side to side

Question 24

Primary side effects of earthquakes
2

Answer 24

1.Ground shaking - buildings, bridges, road sand infrastructure collapse
2.Crustal fracturing - earth’s crust cracks

Question 25

Secondary side effects of earthquakes 4

Answer 25

1. Liquefaction - rocks become unstable and shaken turn into liquid (unstable for buildings) 2. Landslides - rockslides, mudslides and avalanches (account for a lot of death and damage) 3. Tsunami - underwater earthquakes 4. Aftershocks - occur in area of original earthquake (generally, larger earthquake = more and larger aftershocks)

Question 26

Aftershock statistic

Answer 26

2011 6.3 magnitude earthquake struck Christchurch, New Zealand caused more damage than original 2010 one.

Question 27

Statistic about volcanoes

Answer 27

1500 active volcanoes

Question 28

Volcano primary hazards: 4

Answer 28

1. Lava flows - very hot (1170*) but move very slowly (minimal risk to humans but more to infrastructure) 2. Pyroclastic flows - dense hot rock, lava, ash and gases ejected from volcano (move very fast -100km per hour- and very hot - up to 700 degrees) 3. Tephra and ash falls - large pieces of rock cause injury or death whereas smaller ash travels far and can clog engines or cause roofs to collapse) 4. Gas eruptions - Sulphur dioxide causes acid rain

Question 29

Volcano secondary hazards: 2

Answer 29

1. Lahars - masses of rock, mud and water that are too fast to outrun (caused by melting ice or heavy rainfall after an eruption) 2. Jokulhlaup - snow and ice in a glacier is melted by heat of a volcano (cause sudden and heavy floods that catch people unawares)

Question 30

How do tsunamis form?

Answer 30

1 - displacement of a large volume e.g. due to an earthquake 2 - waves radiate from source in all directions 3 - wave height is small and fats wave speed 4 - as wave reaches shore, vacuum effect occurs 5 - wave slows and energy is used to increase wave height (up to 30m)

Question 31

What impact can tsunamis have? 4

Answer 31

1. Can travel inland for several miles and sweep away buildings, trees and people 2. wash away soil - make infertile or salination can occur (becomes too salty) 3. completely change landscape - small islands washed away completely 5. spread of disease like cholera by contaminated water sources

Question 32

Why are tsunami time travel maps useful?

Answer 32

Give an estimated time to evacuate by Help stakeholders plan and prepare for tsunami events Baes off of epicentre

Question 33

When do hazards become disasters?

Answer 33

When they strike a vulnerable population that cannot cope using its own resources

Question 34

What is risk equation?

Answer 34

(Hazard x vulnerability) / Capacity to cope

Question 35

How might a developing country fair worse than a developed country? 3 ways

Answer 35

Higher number of deaths More reliance on international aid Slower economic recovery

Question 36

Why might a developing country fair worse than a developed country? 5 reasons

Answer 36

1 Less access to education 2 Poor quality housing/ no specialised infrastructure 3 Worse healthcare 4 High population Density 5 Less accessibility - aid struggles to get there

Question 37

What are the 3 progressions of vulnerability in the PAR model? Give an example for each

Answer 37

Root cause - Structures Dynamic pressure - Local investment Unsafe conditions - unprotected buildings and infrastructure

Question 38

2023 Syria - Turkey earthquake - how were they geographically at risk?

Answer 38

1. 4 tectonic plates interact - one of world's most seismically active fault zones 2. Aid route was damaged after earthquake - delaying delivery of aid

Question 39

2023 Syria - Turkey - how were they at risk politically?

Answer 39

1. On ongoing civil war has destabilised the country and its economy 2. Widespread political corruption

Question 40

2023 Syria - Turkey - how were they at risk socially?

Answer 40

1. dealing with cholera outbreak when earthquake hit 2. over 2 million people already lived in temporary or unsafe shelter/ buildings

Question 41

2023 Syria - Turkey - how were they at risk economically?

Answer 41

1. low income country 2. very few resources were dedicated to disaster prevention and preparation

Question 42

What does PAR model stand for?

Answer 42

Pressure and Release

Question 43

How are earthquakes measured?

Answer 43

Magnitude - - MMS - (goes from 1 - infinite but generally stops at 10) - scale is logarithmic Intensity - - Modified Mercalli Intensity scale - takes observations from people who experienced the earthquake - roman numeral scale (I to X)

Question 44

How are volcanoes measured?

Answer 44

Eruptions - - Volcanic explosivity index - 0 to 8 - amount and height of volcanic material ejected, how long eruption lasts, qualitative description terms

Question 45

Why are hazard profiled useful? 2

Answer 45

1. They can compare different or similar tectonic events 2. helps decision makers plan how to use resources depending severity of disaster

Question 46

What are some hazard profile characteristics? 6

Answer 46

Magnitude Speed of onset Duration Areal extent Spatial predictability Frequency

Question 47

What is one way in which hazard profiles are not useful?

Answer 47

Don't compare every aspect of a tectonic event

Question 48

What is one statistic of tectonic event deaths and low income countries?

Answer 48

LI countries account for 10% of worlds population but 23% of world disaster deaths

Question 49

Compare how LI countries are affected vs high income countries:

Answer 49

LI countries experience more deaths HI countries experience more economic losses - infrastructure is more expensive

Question 50

What is World Risk Index?

Answer 50

Number is assigned to a country - higher number = higher disaster risk Allows for comparison of risk globally Looks at exposure, vulnerability, susceptibility etc

Question 51

How can Governance affect natural disasters?

Answer 51

1. enforcing building regulations 2. quality of existing infrastructure 3. making preparedness plans 4. efficiency of emergency services 5. quality of communication systems 6. public education 7. level of corruption - what money is spent on

Question 52

Haiti earthquake date, magnitude and focus:

Answer 52

12 January 2010 Magnitude = 7 Shallow focus = 13km

Question 53

Haiti earthquake immediate impact:

Answer 53

Epicentre was only 24km from Port- au- prince (countries capital)

Question 54

Haiti earthquake secondary impact:

Answer 54

Liquefaction caused buildings to sink

Question 55

Why was Haiti so badly impacted? 5 ways

Answer 55

1. Developing country 2. High level of corruption at both national and local GOVs 3. Lack of building controls and regulations 4. Lack of disaster preparation 5. Much of population still lives in poverty

Question 56

How was Haiti impacted?

Answer 56

1. only one airport, several ports, few main roads - damaged badly so crucial aid was delayed 2. 1/4 of Gov officials were killed 3. 2010 October an outbreak of cholera occurred

Question 57

Haiti recovery and aid

Answer 57

US$ 13 billion - mostly remained in hands of orgs (not GOV) Overseas projects were not allowed to be run by GOV due to be Haiti corruption - made it more expensive and Haiti found it difficult to be independent

Question 58

3 good things 3 bad things That came from Haiti

Answer 58

1. increase in preparedness drills 2. building of new shelters 3. increased educational outreach 1. Increase in gang violence 2. political instability - assassination of President in 2021 3. did not receive aid to properly recover

Question 59

Sichuan China earthquake date and magnitude

Answer 59

12 May 2008 magnitude = 7.9

Question 60

Secondary impacts

Answer 60

1. 45.5 million were affected in 10 provinces 2. highest recorded homeless count in history 3. landslides led to a 1/4 of earthquake related deaths

Question 61

Japan Honshu island earthquake

Answer 61

magnitude = 9 Led to tsunami - waves were 10m high in some places

Question 62

Secondary impacts

Answer 62

High income country - highest magnitude but fewest deaths Why? Good building infrastructure (75%) Good education - Disaster day and regular earthquake alarm drills in school (4 a year) Low level of corruption

Question 63

Indian Ocean tsunami basics

Answer 63

2004 - 9.3 Banda Ache 5 million people affected across 12 countries 1.7 million left homeless US $10 billion overall cost

Question 64

Eyjafjallajokul volcanic eruption basics

Answer 64

Iceland 2010 Led to 8 days of flight delays Ash and gases clogged aircraft engines 100,000 flights were cancelled

Question 65

How is Philippines geographically vulnerable?

Answer 65

Major convergent plate boundary North and East coasts face Pacific ocean Coastal lowlands

Question 66

How is Philippines socially vulnerable?

Answer 66

Growing population Rapid urbanisation and poverty 2018 - 18% of pop lived in poverty

Question 67

How to predict earthquakes?

Answer 67

Know which areas are at risk (spatial predictability) Very sudden Precursors - new and not reliable

Question 68

How to predict volcanoes?

Answer 68

1. Increase is SO2 being produced 2. Small earthquakes 3. Temp increasing 4. Surface of volcano swelling

Question 69

How to predict Tsunamis?

Answer 69

Early warning system - seismic sessions detect earthquake in water DART system - sea bed sensors If tsunami had been n place for 2004 Indian early warning systems, things may have been different... took 2 hours to reach some places Sudden low tide - vacuum effect

Question 70

What is hazard management cycle?

Answer 70

Mitigaton- preventing hazard events and minimising effects (long term) Preparedness - preparing to deal with a hazard (short term) Response - immediate response to hazards (aid) Recovery - long term 'getting back to normal'

Question 71

What is an example of each stage in the hazard management cycle?

Answer 71

M - buildings P - public education, evacuation plan R - aid, shelter, clean water R - rebuilding, reopening businesses schools etc

Question 72

What are the best mitigation strategies?

Answer 72

Land use zoning Diverting lava flows GIS mapping Specialised buildings

Question 73

What are the best adaption strategies?

Answer 73

High-tech monitoring Crises mapping - Haiti Public education Community preparedness and adaption

Question 74

What is Land-use zoning?

Answer 74

Land is divided into zones based on the risk of damage from eruptions - this determines how the land may be used e.g. if settlements are allowed to be built New Zealand (developed countries)

Question 75

What is diverting lava flows?

Answer 75

Building buildings and digging channels However, path Laval takes can be difficult to predict, terrain has to be suitable etc Not very effective Successful in 1983 Mount Etna eruption

Question 76

What is hazard-resistant design?

Answer 76

Collapsing buildings are one of the main causes of death and damage Volcano: Roofs of houses sloped to stop build up of ash Earthquake: Counterweight, deep foundations Tsunami: Buildings elevated and anchored Retrofitting - making adjustments to existing buildings

Question 77

What is high-tech monitoring?

Answer 77

GIS mapping - create hazard maps and manage hazards more effectively Satellite communication tech - expensive for some countries Mobile phone tech - Japan used to issue alerts and updates 2011

Question 78

What is crises mapping?

Answer 78

Haiti earthquake - lack of communication systems meant aid distribution was difficult Ushahidi website - crowdfunding Real time updates collected by volunteers Nepal - 2015 earthquake, volunteers rode bikes into rural communities to collect data and determine how vulnerable they are

Question 79

What is public education?

Answer 79

Japan is very good - disaster preparation day 4 drills in schools yearly

Question 80

What is community preparedness?

Answer 80

2004 indian tsunami - local Thailand monks helped 200 get to safety as they predicted the tsunami Organise practise drills Know local area best Create a list of vulnerable people who may need special assistance

Question 81

Who are the key players in managing loss?

Answer 81

Aid donors - emergency, short term and long term NGOs - Haiti Role of insurance Communities