Tectonics

Question 1

Jökulhlaup

Answer 1

A glacial outburst flood

Question 2

pyroclastic flow

Answer 2

a mixture of rock fragments gas and lava that travels quickly

Question 3

lahar

Answer 3

a volcanic mudflow comprised of fine sand and silt

Question 4

tephra

Answer 4

materials such as rock fragments ejected into the air during a volcanic eruption

Question 5

magnitude

Answer 5

the strength of an earthquake

Question 6

intensity

Answer 6

the power of a hazard

Question 7

benioff zone

Answer 7

the area where friction is created between colliding tectonic plates

Question 8

fault line

Answer 8

a place where the fault can be seen or mapped on the surface

Question 9

divergent/constructive boundary

Answer 9

plates move away from each other

Question 10

convergent/destructive boundary

Answer 10

plates move towards each other

Question 11

conservative plate boundary

Answer 11

plates slide past each other horizontally

Question 12

what is the hazard-risk equation?

Answer 12

risk = (hazard x vulnerability) / capacity to cope with

Question 13

name two pressures in the pressure and release model

Answer 13

technological accidents and conflicts

Question 14

define a disaster

Answer 14

a hazard that has an adverse affect on people or property

Question 15

What does the Richter scale measure?

Answer 15

The Richter scale measures the magnitude of an earthquake based on the amplitude of seismic waves.

Question 16

What does the Mercalli scale measure?

Answer 16

Mercalli Intensity scale assesses the intensity of an earthquake based on observed effects and damage to structures, as perceived by people.

Question 17

What is VEI and what does it measure?

Answer 17

VEI stands for Volcanic Explosivity Index. It is a scale used to measure the magnitude of volcanic eruptions based on the volume of volcanic material ejected, the height of the eruption column, and other factors.

Question 18

what are the four stages of the hazard management cycle?

Answer 18

prediction/mitigation, preparedness, response, recovery

Question 19

what is a hydrometeorological hazard?

Answer 19

In simpler terms, a hydrometeorological hazard is a dangerous event caused by weather or water, like floods, storms, or hurricanes.

Question 20

what are earthquake hazard profiles?

Answer 20

Earthquake hazard profiles provide information about the seismic risks in a specific region. These profiles include details such as the frequency and magnitude of earthquakes, the geological characteristics of the area, and the potential impact on structures and communities. Hazard maps may also be part of these profiles, illustrating areas at higher risk. Understanding earthquake hazard profiles is crucial for implementing effective building codes, emergency preparedness, and risk mitigation strategies in seismic-prone regions.

Question 21

Identify one process that occurs only at destructive plate boundaries

Answer 21

One process that occurs only at destructive plate boundaries is subduction. In this process, one tectonic plate is forced beneath another due to their collision. As the descending plate sinks into the Earth’s mantle, it often leads to the formation of deep-sea trenches and volcanic arcs. Subduction zones are typically associated with intense geological activity, including powerful earthquakes and volcanic eruptions.

Question 22

what is a secondary hazard?

Answer 22

an event that happens as a result of a primary natural disaster or event

Question 23

Explain the tectonic hazards that may result from volcanic activity

Answer 23

volcanoes and earthquakes

Question 24

Explain two characteristics of volcanic hotspots

Answer 24

a fixed magma source
the formation of volcanic island chains

Question 25

Explain why volcanic eruptions vary in their magnitude

Answer 25

type of magma (basaltic eruptions are less explosive)
gas content (more gas = more explosivity)
volcano type

Question 26

Explain the value of Park’s hazard-response curve in understanding the management of the impacts of tectonic hazards.

Answer 26

1. Asses the damage to a country/region by displaying it on a disaster response curve
2. Measures 3 factors: quality of life, level of economic activity and social stability
3. Measures 4-5 stages

Question 27

what is the value of hazard mitigation strategies?

Answer 27

They assist in predicting when tectonic hazards might happen, understanding the impact they could have, and figuring out how to manage and lessen their effects. These frameworks use organized ideas to make studying earthquakes and volcanoes easier and help us plan better for safety.

Question 28

With reference to earthquake waves, explain two reasons why it is difficult for buildings to remain intact during an earthquake event.

Answer 28

1. Shaking Ground:The ground shakes vigorously during an earthquake, and this shaking can cause buildings to sway or vibrate. If a structure is not well-designed or lacks proper reinforcement, it may not withstand this movement, leading to structural damage or collapse.
2. Energy Transfer: Earthquake waves carry a lot of energy, and when they reach a building, that energy tries to move through and around it. If a building isn’t designed to absorb or distribute this energy effectively, it can experience stress and damage, making it challenging for the structure to remain intact during the seismic event.

Question 29

Explain the link between plate boundary type and the strength of earthquake waves

Answer 29

Different types of plate boundaries affect how strong earthquakes can be:

1. Pulling Apart (Divergent):
   
   • Link: Earthquakes are not very strong.
   • Why: Plates move slowly away from each other, causing mild shaking.
2. Crashing Together (Convergent):
   
   • Link: Strong earthquakes happen here.
   • Why: Plates collide or one goes beneath the other, creating powerful shaking.
3. Sliding Past Each Other (Transform):
   
   • Link: Strong earthquakes can occur.
   • Why: Plates rub against each other, building up stress and causing significant shaking when released.

Question 30

Explain the geographical criteria that can be used to decide if a tectonic event is a hazard, disaster or mega-disaster.

Answer 30

1. Tectonic Hazard:
   
   • Criteria: Possible danger.
   • Explanation: When there’s a chance of something harmful, like an earthquake.
2. Tectonic Disaster:
   
   • Criteria: Real impact.
   • Explanation: When the harmful event actually happens and causes damage.
3. Tectonic Mega-Disaster:
   
   • Criteria: Extremely big and damaging.
   • Explanation: When the harmful event is exceptionally powerful and causes widespread devastation.

Question 31

Explain the correlation between the magnitude and intensity scales used for measuring earthquakes and their secondary hazards

Answer 31

The magnitude scale measures how powerful an earthquake is overall, while the intensity scale describes its effects in specific areas. Higher magnitudes indicate more power and a higher likelihood of secondary hazards like landslides and tsunamis. The intensity scale helps understand localized impacts, such as building damage, caused by these secondary hazards.

Question 32

Assess the reasons why earthquakes create more disasters than volcanic eruptions

Answer 32

Earthquakes create more disasters than volcanic eruptions because they can happen in many places globally, affect densely populated areas, and trigger additional hazards like tsunamis and landslides, making their impact more widespread and severe. Volcanic eruptions, on the other hand, are often localized and may impact fewer people.

Question 33

Assess the relative importance of the physical characteristics of volcanic eruptions in creating risk for people

Answer 33

The physical characteristics of volcanic eruptions, like eruption type, explosiveness, and lava flow, are crucial in determining the risk for people. The more explosive and widespread an eruption is, the higher the risk, as it can lead to lava flows, ash clouds, and other hazards that pose threats to communities. Understanding these physical traits is essential for effective risk assessment and planning for volcanic events.

Question 34

where do intraplate earthquakes happen?

Answer 34

can happen anywhere the crust is cracked
small movements build up friction and strain overtime which suddenly releases causing low mag. earthquakes

Question 35

what can isostatic readjustment cause

Answer 35

isostatic readjustment can cause earthquakes as the crust moves up and down

Question 36

intraplate volcanoes

Answer 36

oceanic plates: magma rising though the mantle is able to melt its way through creating volcanoes that grow from the sea bed
continental plates: much thicker but get stretched enough in places for the magma from a hot spot to break through

Question 37

mantle plumes

Answer 37

molten material rises from the outer core to about 700km beneath the crust or lithosphere

Question 38

what do mantle plumes create

Answer 38

hot spots - where magma rises through the asthenosphere and may break through the crust

Question 39

mantle convection

Answer 39

heat radiating from the inner core causes a plate to convect (travel). the convection cells make contact with the base of the crust causing friction and so drag the crust along in the general direction of the convection.

Question 40

palaeomagnetism and sea floor spreading

Answer 40

the outer core is mainly liquid iron and it convects. This creates a magnetic field for the earth which flips every 100 000 years. When igneous rocks cool to form solid rocks they trap the magnetic field at a point in time. This can be used as a record.

Question 41

subduction and slab pull

Answer 41

at destructive plate boundaries denser oceanic plates are subducted under less dense continental plates eg at deep ocean trenches

as a slab of oxeanic plate dcends it often pulls with some force the rest of the plate behind it

Question 42

ridge push

Answer 42

where the new crust formed at divergent
plate margins is less dense than the surrounding crust and so it rises to form oceanic ridges

Question 43

what is shown by magnetic field directions in rocks

Answer 43

continents have moved and rotated

Question 44

plate boundary diagrams

Answer 44

Question 45

at what boundary do the strongest earthquakes occur

Answer 45

destructive: this is where here is the greatest friction and build up of pressure betwen plates

destructive plate boundaries = most destructive

Question 46

when are volcanoes more explosive

Answer 46

where the magma is viscous with a high silica and gas content. These are usually found at destructuve plate margins with subduction where the subducted plate is melted usually under a continental plate

Question 47

what are the 3 types of earthquake waves

Answer 47

P (primary) waves, S (secondary) waves and L (Love) waves

Question 48

primary waves

Answer 48

arrives first, moves fast and throigh solid rock and fluids, compresses in the direction of travel

Question 49

secondary waves

Answer 49

slower than P waves and moves more up and down only through solid rock

Question 50

love waves

Answer 50

only travels through the surface of the crust, fastest of the surface waves and moves from side to side horizontally as it moves forward

Question 51

how do waves move the ground in different ways and what differing effects do they have?

Answer 51

Shockwaves move the ground in different ways, with S waves being the most damaging of the body waves due to high amplitude (up and down) and slow speed. Love waves are the most damaging of the surface waves, arriving after P and S waves have weakened buildings

Question 52

what are some hazards caused by earthquake waves?

Answer 52

crustal fracturing
ground shaking
liquefaction
landslides

Question 53

crustal fracturing

primary

Answer 53

shockwaves travel quickly through rock and can increase stress until the rock fractures
causes faults which can rupture causing damage to anything on them

Question 54

ground shaking

primary

Answer 54

happen quickly in short bursts and multiple directions
buildings may be damaged or collapse whch presents a real threat to their inhabitants

Question 55

liquefaction

secondary

Answer 55

occurs when shokwaves travel through loose unconsolidated material shaking it so that it acts like a fluid
causes buildings to tilt or collapse and threatens underground cables or pipes

Question 56

landslides

secondary

Answer 56

shockwaves loosen rock on steep slopes causing it to move downslope en mass
may hit settlements or block roads

Question 57

ash falls

Answer 57

– Forced to a high altitude so they can be carried around the planet in the atmosphere and disrupt flight paths
– can fall locally causing roofs to collapse.
– can get into machinery and electronics causing them to fail

Question 58

pyroclastic flows

Answer 58

– Dense mixture of superheated solid particles (tephra) and poisonous gases which erupt from a crater moving down the side of a volcano.
– travel at great speed of up to 700 km an hour
– can cause flooding due to blocked River channels

Question 59

gas eruptions

Answer 59

• gases such as sulphur can cause acid rain when combined with water vapour damaging water and plants.
  – sulphur may also cool the Earth when it’s carried high into the atmosphere by blocking the sons energy. This can cause crop failures and famine.

Question 60

lava flows

Answer 60

– Molten magma is erupted from volcanoes flows down the sides until it calls
– Basaltic lava flows fastest making it the most dangerous

Question 61

lahars

Answer 61

– A mixture of water and erupted volcanic material various sizes
– flow very fast (60 km an hour) down River valleys.
– the water make come from rainfall, a crater lake, or the melting of snowcap on the top of a volcano

Question 62

jokulhlaups

Answer 62

– Where a volcano erupts underneath an ice cap the heat will melt some of the eyes.
– the meltwater builds up around the top of the volcano trapped by the surrounding ice.
– eventually the warm water will melt and lift the ice away from the ground causing the water to burst out from under the ice and flow rapidly to lower ground

Question 63

features of tsunamis

Answer 63

• the largest wave is not the first
• long wavelength in open ocean but short in shallow water
• very far in deep water but slow in shallow
• low in open ocean but high in shallow

Question 64

causes of tsunamis

Answer 64

an undersea earthquake may cause a rapid movement of the seabed. if this is up or down then water is displaced creating a wave

tsunamis can also occur due to volcanic eruptions on islands, and major landslides into the sea or underwater on the edge of continental shelves

Question 65

pressure and release model

Answer 65

Question 66

natural hazard

Answer 66

A natural event that causes disruption to daily lives or death and destruction

Question 67

disaster

Answer 67

A disaster occurs when the scale of an impact of a natural hazard are great. It is measured by the number of deaths (UN suggests 500+) all the cost of the damage (millions of dollars).

Question 68

mega-disaster

Answer 68

a mega-disaster occurs when they are over 2000 deaths as a result of a natural hazard and a GDP reduction of 5% or more.

Question 69

what is the hazard risk equation?

Answer 69

hazard risk involves potential loss of life and injury and destruction and damage to buildings infrastructure in an area.

The equation involves consideration of the hazard, degree and frequency of exposure to the hazard, vulnerability the people and systems, and the capacity to recover.

Risk = Hazard x Vulnerability
R = H x V

Question 70

resilience

Answer 70

The ability of capacity of community or society to withstand the effects of a natural hazard through methods of adaption and recovery

Question 71

vulnerability

Answer 71

The extent to which community could be damaged or disrupted by hazard. Is based on the human geography of a community or area.
Factors include:
– the location of settlements
– peoples knowledge and understanding
– peoples ability to prepare, react to and withstand the effects of a hazard
– the presence of advance warning systems
– the involvement of local people in planning and preparation.

Question 72

how is development measured?

Answer 72

– Economic development (GDP per capita)
– social development
– social and economic development (HDI)
– political development
– environmental development

Question 73

trends in deaths (social)

Answer 73

– There are higher losses of life and developing an emerging countries then in HICS
– people developed an emerging countries are more vulnerable due to low understanding link to levels education and lower levels of technology because there’s less money to spend on a size buildings, warning systems or emergency rescue and healthcare.
– emerging countries have rapidly growing cities which increase rested denser populations and uncertainties over building codes and land use zoning
– Corruption and government departments

Question 74

how are the economic impacts of a hazard different in developed and developing countries?

Answer 74

– When the characteristics of a tectonic hazard are comparable, it is clear that developed countries have greater costs of damage than emerging or developing countries.
– Richard countries have more expensive buildings, infrastructure and technology to be damaged.
– developing countries may only have significant construction in urban areas, if rural areas are affected by hazard cost tend to be low.
– cost to emerging countries are increasing because they have increased construction and rapid urban growth.

However even low damage costs can be expensive to poor people who have to buy new construction materials, or find a new job because their place of work has been destroyed

Question 75

moment magnitude scale

Answer 75

• for earthquakes
• logarithmic where each level has 10x the energy of the level below

Question 76

mercalli intensity scale

Answer 76

• for earthquakes

Question 77

volcanic explosively index

Answer 77

• magnitude
• logarithmic scale where each level has 100 times the energy of the level below it

Question 78

tsunami intensity scale

Answer 78

• logarithmic where each level has twice the energy of the level below

Question 79

what 6 characteristics to tectonic hazards profiles consider?

Answer 79

– spatial predictability
– aerial extent
– frequency
– magnitude
– speed of onset
– duration

Question 80

spatial predictability

Answer 80

an area that has never had an event will experience greater impacts as people and places will be unprepared

Question 81

areal extent

Answer 81

The larger the area affected by the event, the greater the impact will be as more people and places are affected

Question 82

frequency

Answer 82

an event that occurs often is more likely to create cumulative impact (although rare events have more energy)

Question 83

magnitude

Answer 83

The greater the amount of energy released by an event, the greater the impacts are like to be

Question 84

speed of onset

Answer 84

The faster the event occurs, the shorter the warning time and the greater the impacts as places are unprepared.

Question 85

duration

Answer 85

The longer an event lasts, the more likely that there will be greater impacts

Question 86

how can you compare hazard profiles?

Answer 86

– Volcanoes have very specific locations and usually give signs they are about to erupt, but earthquakes are found in broad zones and are unpredictable.
– not all under seas earthquakes produce tsunamis.
– Hazard profile showed differences in social and economic impacts between countries at different stages of development

Question 87

summary diagram of influences on vulnerability and resilience

Answer 87

Question 88

what are the reasons for tectonic disaster trends?

Answer 88

1. population increase – more people affected.
2. urbanisation rates high – more people affected in a small area.
3. Widespread poverty – people living in risky areas in insecure housing.
4. More expensive construction and belongings in increasing the cost of damage.
5. Inequality – the increased risk of those lacking access information and services.
6. Climate change – increasing the severity of climate, weather, river and biological hazards.
7. Environmental degradation – reducing protection from natural systems.
8. More reporting – information through media

Question 89

what can be the effects of mega-disasters?

Answer 89

– over 2000 deaths or
– over 200,000 people made homeless or
– losses of 5% of National GDP or higher or
– dependence on external aid for one year or longer

– Global energy policies (nuclear power stations damaged)
– global and regional economic activities (international air travel disrupted)
– global pollution
– multi-national losses of life
– global temperatures and regional food supplies affected

Question 90

multiple hazard zones

Answer 90

hazards can be grouped into several categories:
- meteorological (such as strong winds in a storm)
- hydrological (such as river floods)
- geophysical (such as tectonic and mass movements)
- climatological (such as long term drought)
- biological (such as a diseas)

Question 91

what are some deadly combinations of multiple hazard zones?

Answer 91

• volcanic eruptions colliding with heavy rains or tropical cyclones; produces a heavy rain and tephra mix creating lahars
• earthquakes in remote areas of developing countries where there are no health services may lead to outbreaks of disease, where there is no clean water and medicine

Question 92

predicting and forecasting: earthquakes

Answer 92

• predicting the TIMING of earthquakes is impossible
• there is some evidence that animals and birds can sense danger but only just before
• modern seismic monitoring and communications allow for warning to be given minutes before shockwaves arrive
• foreshocks can be an indication of a larger event but the pattern is not certain until after
• The absence of earthquakes along and known fault as a concern as it shows that stress and strain a building up instead of being released by smaller earthquakes.
  – earthquakes may travel along a fault line overtime until it’s possible to say which part of the fault will move next (but not when)
  – some faults are unknown and earthquakes catch people by surprise

Question 93

predicting and forecasting: volcanoes

Answer 93

– Volcanoes have a fixed location and this allows constant monitoring. However constant monitoring requires technology and is expensive. So many volcanoes and developing countries are not monitored.
– geological evidence of past eruptions provides clues about the type of extent of future eruptions.
– measurements can include gas emissions, harmonic tremors, bulging of the volcano, and the composition of magma. There are usually changes in these readings, before an eruption, which allows relatively accurate prediction of warnings to be given, although the exact magnitude is more difficult to forecast

Question 94

predicting and forecasting: tsunamis

Answer 94

– Any submarine earthquake may create a tsunami, especially if it is large magnitude on subduction zones with mega thrust.
– warning systems exist in the Pacific and also in the Indian ocean (after 2004), based on size Moura readings percent buoys monitoring movement of the sea
– computer modelling has been used to predict arrival times and wave heights but does not always accurately count for ocean depth or the shape of the sea floor

Question 95

why is prediction and forecasting important?

Answer 95

There are several groups of people (players) involved with predictable forecasting. At the forefront of these are the scientist who are working to understand the Temic processes and carry out monitoring using the latest tech technology. Prediction forecasting is hugely important to reducing future rest, although some believe it will never be possible to predict earthquakes precisely so uncertainty will always remain.

Question 96

what are the three hazard management stages?

Answer 96

• pre-disaster:
  risk assessment
  mitigation/prevention
  preparedness

💥warning/ evacuation

• response:
  Saving people
  Providing immediate assistance
  Assessing damage

– post-disaster:
Ongoing assistance
Restoration of infrastructural services
Reconstruction (settlement/relocation)
Economic and social recovery
Ongoing development activities
Risk assessment/mitigation/prevention

Question 97

parks model

Answer 97

Question 98

strategies to modify events

Answer 98

• geographic information systems (GIS):
  shows where movement was greatest and reveals where land-use zoning could be imposed including regulations requiring hazard resistant designs
• hazard zones:
  hazard zoning maps can forecast where the biggest dangers are. people can be prevented from living in these areas through land-use zoning.
• modifying the tectonic event:

earthquakes: Modifying earthquakes as difficult because of their power and unpredictable.They can be avoided by not living near plate boundaries or faults or designing buildings to withstand powerful seismic waves.

volcanoes: modifying some volcanic hazards as possible, hazard learning maps forecast where the biggest danger are and land use zoning stops people living there; training crater lakes reduces the formation of lahars; lava flows can be diverted by barriers or diversion channels or sprayed with water to cool and slow movement.

Tsunamis: tsunamis can be modified at the coast to prevent development near the shore (building offshore barriers, higher and stronger, using natural defences like mangrove forests)

Question 99

mitigation

Answer 99

involves actions and interventions by a community that will reduce the severity of a hazard, such as reducing vulnerability and increasing resilience

Question 100

adaptations

Answer 100

changes or responses to a hazard situation designed to help a community cope with a hazard such as taking precautions

Question 101

ways to modify vulnerability and resilience:

Answer 101

– Hazard risk mapping: modelling of hazard zones within an area for example liquid action areas or Lahar routes
– land use zoning: strict planning regulations to stop building in risky areas.
– food supplies: increasing food production with better storage methods
– monitoring and warning systems: to give people enough time to evacuate.
– hazard resistant designs: any construction to be built to a specification strong enough to withstand impacts.
– investment services: healthcare systems can be better prepared and education can raise the level of a community understanding of hazards and actions to take.
– improved evacuation routes: to enable people to escape in time

Question 102

ways to modify loss:

Answer 102

– Rescue teams: fully equipped with the latest technology.
– emergency relief aid: involving food, water, sanitation and shelter as well as medical care
– community volunteers: local people specifically trained for emergency events to help guide and help other locals.
– Insurance: large or microscale insurance to reduce financial losses for individuals and families especially lively had been lost.
– evacuation: move away from the areas that may be hit again, including permanent settlement locations
– development aid: long-term assistance from other countries to help rebuild what has been lost

Question 103

what is the asthenosphere?

Answer 103

zone of Earth’s mantle lying beneath the lithosphere and believed to be much hotter and more fluid than the lithosphere

Question 104

what’s the difference between surface and body waves?

Answer 104

Body waves can travel through the Earth’s inner layers, but surface waves can only move along the surface of the planet like ripples on water

Question 105

convection current diagram

Answer 105

Question 106

structure it the earth with mantle plumes and hot spots

Answer 106

Where there is a spot of extra energy and heat a mantle plume may form which can cause a hot spot

Question 107

what is paleomagnetism and sea floor spreading?

Answer 107

the sea floor spreads outwards because it is at a different plate margin which means it is pushing away and causing different bands of rock to face different directions depending on which direction they were pointing when the earths magnetic field were at north or south