Tectonics Flashcards
1
Q
Describe the inner core
A
solid ball of mostly iron, some nickel
high pressure
5,200 degrees
2
Q
Describe the outer core
A
alloy of nickel and iron
4500-5000 degrees
molten movement creates magnetic field
3
Q
Describe the mantle
A
magnesium, iron and silica
peridotile
high temp and pressure form of basalt
becomes ductile at depth
4
Q
Describe the crust
A
oceanic (thinner and denser)
continental (thicker and lighter)
5
Q
What is the boundary between the crust and mantle called
A
The Moho
6
Q
How thick is the mantle
A
2,900km
7
Q
Explain each type of crust
A
Oceanic: dark in colour mafic rocks (less silica) covers most of earth continental: lighter in colour felsic rocks (more silica)
8
Q
Explain plate boundaries
A
major, minor and micro
plates move around 2cm a year
most under oceans
9
Q
Name the 7 major plates
A
African Antarctic Eurasian Pacific Indo-Australian North American South American
10
Q
Name 3 major theorists and their theories
A
Wadati (1924) - intermediate to deep earthquake zone called the Wadati-Benioff line
Hess (1945) - aged rocks on Atlantic floor and proved oceanic spreading
Wegener (1912) - proposed Pangaea and continental drift
11
Q
Name the evidence for plate tectonics
A
continents seem to fit together
fossilised remains of plants and animals on different continents
age of rock on each side of a ridge
evidence of glaciation
12
Q
What studies confirmed sea floor spreading
A
paleomagnetism studies which studies changes in the earths magnetic field
13
Q
Explain intraplate hotspots
A
a rise of a deep mantle plume caused by a slow convection of highly viscous material
as the plate moves over the plume, a chain of volcanic islands may be formed
14
Q
What do conservative Plate boundary form
A
Transform faults and powerful earthquakes
15
Q
What do destructive subduction Plate boundary form
A
Volcanoes
Fold mountains
Deep ocean trench
Earthquakes
16
Q
What do destructive subduction under water Plate boundary form
A
Underwater volcanoes
Deep ocean trench
Earthquakes
Island arcs
17
Q
What does a destructive collision Plate boundary form
A
High fold mountains and severe earthquakes
18
Q
What does a constructive Plate boundary form
A
Mid Atlantic ridge New crust Rift valleys Submarine volcanoes Shallow focus earthquakes
19
Q
What are the three ways plates move
A
Convection currents
Slab pulling
Ridge pushing
20
Q
Explain convection currents
A
Heat from the breakdown of radioactive isotopes deep in the mantle
Hot pulls up and cold falls
21
Q
How is the earth dynamic
A
Because of the internal heat
22
Q
Why is this theory not correct
A
The plates move faster than the currents
There are no currents large enough to move plates
23
Q
Explain slab pulling
A
When a plate that’s being forced down pulls the rest of the plate with it
24
Q
Explain ridge pushing
A
When plates are being forced away from each other are being pushed due to new magma forming
25
Explain the distribution of volcanic hazards
Ring of fire
Mainly at plats boundaries
Africa Rift Valley has hotspots
26
Explain the distribution of tsunamis
Plate boundaries
Ring of fire
Japan at very high risk
More exceptions as they move
27
Explain the distribution of earthquakes
Ring of fire
Eurasia
Plate boundaries and intraplate
28
Name a key constructive plate boundary
```
The mid Atlantic ridge
Oceanic - oceanic
Black smokers
Creates deep Rift Valley
Spreads 2-5 cm a year
Eurasian/Africa and North American plate
```
29
Name a key destructive collision Plate boundary
```
Himalayas
2 continental
Indian and Eurasian plates
Earthquakes
Grow 2-5cm a year
```
30
What is a mountain building event called
Oroganies
31
Name a key destructive subduction Plate boundary
Andies
Nazca and South American plates
3.8cm a year
32
What is the Wilson cycle
The cyclic opening and closing of ocean basins
| One side destroyed other side made
33
Name a key conservative plate boundary
San Andreas fault
| Pacific and North American plate
34
What is the appearance of a volcano affected by
Type and viscosity of magma, the amount of gas present and the way in which magma is erupted
35
Explain the shape of a strato volcano
```
Explosive and large cone chapel
Subduction zones
Plug and plug dome
Flank cinder cone
Throat
Vent
```
36
Explain the magma in a strato volcano
```
High in silica
Thick
sticky
Lots of gas
High pressure so dramatic explosions
```
37
What is tephra
Ejected material
38
Explain the shape of a shield volcano
Formed by frequent, gentle eruptions
Constructive Plate boundary
Vent
Gently sloping sides
39
Explain the magma in a shield volcano
Thin
Runny
Less silica and gas
Runs for long distances
40
Name the five types of eruptions
```
Hawaiian
Strombolian
Vulcanian
Plinian
Surtseyan
```
41
Explain a Hawaiian eruption
No viscous lava
Spatter
Travels several miles
42
Explain a Strombolian eruption
Distinct burst of vicious lava
| Lasts for years
43
Explain a Vulcanian eruption
Short and violent
| Very powerful ash cloud
44
Explain a plinian eruption
Violent
Thick gassy magma
Massive eruption column
45
Explain a surtseyan eruption
Hydromagmatic interaction of water and lava
| Lots of steam and scoria
46
Where does an earthquake originate and where is it felt
Focus and felt at epicentre
47
What type of waves are primary and secondary
Body waves as they travel through the entire surface
48
What type of wages are Rayleigh and love waves
Surface waves as they only travel on the surface
49
Explain primary waves
Forward
Fast compression
Solid and liquids
50
Explain secondary waves
Move sideways and perpendicular
Wave like
Solids only
51
Explain Rayleigh waves
Roll like waves
| Cause of most shaking
52
Explain love waves
Side to side
53
On the Richter scale, by what power does it increase by from each number
X10
54
What does the mercalli scale look at
The impact on the local area
Subjective
Doesn’t always correlate to size of earthquake
55
Name two primary hazards of an earthquake
Crustal fracturing
| Ground shaking
56
Name four primary hazards of a volcano
Lava flows
Ash falls
Pyroclastic flow
Gas eruptions
57
Define a hazard
A natural process that may cause negative effects
58
Define a disaster
A natural event that causes negative effects
59
What is a man made disaster known as
Anthropogenic hazard
60
The UK government declare a national emergency when
The event threatens to seriously damage human welfare, the environment or security
61
What does the UN class as a disaster
Any event that causes more than 500 deaths
62
What does EMDAT class as a disaster
More than 10 deaths
63
What does the UN class as a mega disaster
More than 2000 deaths
Or 200,000 homeless
Or 5% reduction in GDP
64
Define vulnerability
The potential to be harmed
65
Define resilience
Capacity to recover quickly
66
Name three reasons why a place may be vulnerable
Population
Natural resources
Ability/willingness to prepare/recover
67
Name 11 things we need to consider when thinking about vulnerability of a place
```
Physical geography
Resilience
Adaption
Preparedness
Protection
Level of development
Wealth
Governance
Education
Technology
Demographics
```
68
Name three counties that are most vulnerable to physical and human hazards
The Philippines
Papa New Guinea
El Salvador
69
What are the three p’s when it comes to planning for hazards
Prediction, protection and preparation
70
Is the number of earthquakes increasing or decreasing
Statistically increasing
71
Why may the frequency of earthquakes not actually be increasing
Historical records may be inaccurate
More population to be effected
Technology improvements mean we can detect smaller earthquakes
72
Why is the number of deaths decreasing
Mitigation
73
What is a recent technology used for mitigation
Social media such as lists of shelters, google person finder
74
How can we predict earthquakes
Sampling and sensing
75
How can we protect from earthquakes
Warnings and exclusion zones
76
How can we plan for earthquakes
Drills, education
77
What does the pressure and release model show
That a disaster occurs where social pressures and physical events overlap
78
What does the PAR model suggest
What areas could be modified to reduce the risk
79
Name three positives of event profiles
Compare physical processes in similar events
Allow specific management to be considered
Identify and rank hazards
80
Name three negatives of event profiles
Reliability when comparing events is limited
Hard to compare across hazards
Involved some bias as there is no quantity
81
Name 3 advantages of spearman’s rank
Shows significance of data
Proves/disproves correlation
Doesn’t assume normal distribution
82
Name 3 disadvantage of spearman’s rank
Can be time comsuming and difficult
2 sets of data needed
Results can be misinterpreted
83
What percentage of the Philippines and it’s population is at risk of multiple disasters and
60% of land
| 74% of population
84
How many events does TP have per year
10
85
What 3 factors increase its vulnerability
Growing population
Rapid urbanisation
Poverty increase
86
Where do many of the poor live
In the coast which puts them more at risk
87
What does TP lie on
The Pacific typhoon belt
88
Why are multiple hazards difficult
It drains resources and stretches ability of emergency services
89
What building doing standards are in Manila
8.4 earthquake proof structures
90
What human hazards does TP have
Measles and polio outbreaks
91
Name another reason why natural hazards have increased in frequency
Since 2007 landslides have been included
92
What factor with natural hazards is rising
Financial cost
93
Name 4 reasons why less people are dying
Disaster preparedness, mitigation, response, recovery
94
What is the difference between forecasts and predictions
Forecasts are scientific and free from personal bias whereas predictions are subjective and philosophical
95
Explain earthquake forecasting
Based on statistical likelihood and evidence from seismic monitoring and historical records
Long term forecasts are more reliable than short term
96
Name 5 ways we can possibly predict earthquakes
```
Seismic recurrence
Magma movement models
Animals and p waves
Hydro chemical precursors
Seismic gap theory
```
97
Name 4 ways we can predict volcanoes
Shape of volcanoes
Gas and steam emissions
Temperature changes
Harmonic tremors
98
What is the exam boards definition of a mega disaster
A disaster that has both regional and global impacts
99
Name the 3 mega disasters and why they were classified
Boxing Day tsunami : impacted more than one country, Pacific warning system out in place afterwards
E14 eruption: effected flow of people and capital and limited interdependence
Japan tsunami 2011: radioactive materials spread globally and many countries changed their nuclear energy policies
100
Name two ways in which we modify volcanoes
Mitigation and engineering strategies eg bombing in Edna
101
Name two ways in which we modify tsunamis
Increasing coastal vegetation and building tsunami walls
102
Can we modify earthquakes
No
103
How can we reduce human vulnerability to earthquakes
Skyscrapers that sit on moving balls, retrofitting older buildings, cross bracing
104
Name two ways in which we can modify the vulnerability and resilience to hazards
Warning systems such as FEMA in USA
| Community preparedness such as making sure people are educated and there is money to cover damage
105
Name two ways in which we can modify loss of money
Insurance increased in high risk areas such as Lloyd’s city risk index
Short and long term aid to take pressure off government
106
What do modifications all depend on
The governance of the country
107
What is Parks model also known as
the disaster response curve
108
what is the parks model used to understand
prediction, impact and management of tectonic hazards
109
what is the aim of parks model
to show the effects of hazard on quality of life over a sequence of time
110
How many stages are in this model
5
111
name three advantages of this model
visually effective and easy to interpret
enables similar events to be compared
highlights significance of emergency relief
112
name three disadvantages of this model
generalised model
doesn't account for differences in development
doesn't establish capacity to respond
113
Name another model for disaster management
the disaster risk management cycle
114
what are the 4 parts of the DRMC
preparedness, response, recovery, mitigation
