Tectonics Flashcards
Describe the inner core
solid ball of mostly iron, some nickel
high pressure
5,200 degrees
Describe the outer core
alloy of nickel and iron
4500-5000 degrees
molten movement creates magnetic field
Describe the mantle
magnesium, iron and silica
peridotile
high temp and pressure form of basalt
becomes ductile at depth
Describe the crust
oceanic (thinner and denser)
continental (thicker and lighter)
What is the boundary between the crust and mantle called
The Moho
How thick is the mantle
2,900km
Explain each type of crust
Oceanic: dark in colour mafic rocks (less silica) covers most of earth continental: lighter in colour felsic rocks (more silica)
Explain plate boundaries
major, minor and micro
plates move around 2cm a year
most under oceans
Name the 7 major plates
African Antarctic Eurasian Pacific Indo-Australian North American South American
Name 3 major theorists and their theories
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
Name the evidence for plate tectonics
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
What studies confirmed sea floor spreading
paleomagnetism studies which studies changes in the earths magnetic field
Explain intraplate hotspots
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
What do conservative Plate boundary form
Transform faults and powerful earthquakes
What do destructive subduction Plate boundary form
Volcanoes
Fold mountains
Deep ocean trench
Earthquakes
What do destructive subduction under water Plate boundary form
Underwater volcanoes
Deep ocean trench
Earthquakes
Island arcs
What does a destructive collision Plate boundary form
High fold mountains and severe earthquakes
What does a constructive Plate boundary form
Mid Atlantic ridge New crust Rift valleys Submarine volcanoes Shallow focus earthquakes
What are the three ways plates move
Convection currents
Slab pulling
Ridge pushing
Explain convection currents
Heat from the breakdown of radioactive isotopes deep in the mantle
Hot pulls up and cold falls
How is the earth dynamic
Because of the internal heat
Why is this theory not correct
The plates move faster than the currents
There are no currents large enough to move plates
Explain slab pulling
When a plate that’s being forced down pulls the rest of the plate with it
Explain ridge pushing
When plates are being forced away from each other are being pushed due to new magma forming
Explain the distribution of volcanic hazards
Ring of fire
Mainly at plats boundaries
Africa Rift Valley has hotspots
Explain the distribution of tsunamis
Plate boundaries
Ring of fire
Japan at very high risk
More exceptions as they move
Explain the distribution of earthquakes
Ring of fire
Eurasia
Plate boundaries and intraplate
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
Name a key destructive collision Plate boundary
Himalayas 2 continental Indian and Eurasian plates Earthquakes Grow 2-5cm a year
What is a mountain building event called
Oroganies
Name a key destructive subduction Plate boundary
Andies
Nazca and South American plates
3.8cm a year
What is the Wilson cycle
The cyclic opening and closing of ocean basins
One side destroyed other side made
Name a key conservative plate boundary
San Andreas fault
Pacific and North American plate
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
Explain the shape of a strato volcano
Explosive and large cone chapel Subduction zones Plug and plug dome Flank cinder cone Throat Vent
Explain the magma in a strato volcano
High in silica Thick sticky Lots of gas High pressure so dramatic explosions
What is tephra
Ejected material
Explain the shape of a shield volcano
Formed by frequent, gentle eruptions
Constructive Plate boundary
Vent
Gently sloping sides
Explain the magma in a shield volcano
Thin
Runny
Less silica and gas
Runs for long distances
Name the five types of eruptions
Hawaiian Strombolian Vulcanian Plinian Surtseyan
Explain a Hawaiian eruption
No viscous lava
Spatter
Travels several miles
Explain a Strombolian eruption
Distinct burst of vicious lava
Lasts for years
Explain a Vulcanian eruption
Short and violent
Very powerful ash cloud
Explain a plinian eruption
Violent
Thick gassy magma
Massive eruption column
Explain a surtseyan eruption
Hydromagmatic interaction of water and lava
Lots of steam and scoria
Where does an earthquake originate and where is it felt
Focus and felt at epicentre
What type of waves are primary and secondary
Body waves as they travel through the entire surface
What type of wages are Rayleigh and love waves
Surface waves as they only travel on the surface
Explain primary waves
Forward
Fast compression
Solid and liquids
Explain secondary waves
Move sideways and perpendicular
Wave like
Solids only
Explain Rayleigh waves
Roll like waves
Cause of most shaking
Explain love waves
Side to side
On the Richter scale, by what power does it increase by from each number
X10
What does the mercalli scale look at
The impact on the local area
Subjective
Doesn’t always correlate to size of earthquake
Name two primary hazards of an earthquake
Crustal fracturing
Ground shaking
Name four primary hazards of a volcano
Lava flows
Ash falls
Pyroclastic flow
Gas eruptions
Define a hazard
A natural process that may cause negative effects
Define a disaster
A natural event that causes negative effects
What is a man made disaster known as
Anthropogenic hazard
The UK government declare a national emergency when
The event threatens to seriously damage human welfare, the environment or security
What does the UN class as a disaster
Any event that causes more than 500 deaths
What does EMDAT class as a disaster
More than 10 deaths
What does the UN class as a mega disaster
More than 2000 deaths
Or 200,000 homeless
Or 5% reduction in GDP
Define vulnerability
The potential to be harmed
Define resilience
Capacity to recover quickly
Name three reasons why a place may be vulnerable
Population
Natural resources
Ability/willingness to prepare/recover
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
Name three counties that are most vulnerable to physical and human hazards
The Philippines
Papa New Guinea
El Salvador
What are the three p’s when it comes to planning for hazards
Prediction, protection and preparation
Is the number of earthquakes increasing or decreasing
Statistically increasing
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
Why is the number of deaths decreasing
Mitigation
What is a recent technology used for mitigation
Social media such as lists of shelters, google person finder
How can we predict earthquakes
Sampling and sensing
How can we protect from earthquakes
Warnings and exclusion zones
How can we plan for earthquakes
Drills, education
What does the pressure and release model show
That a disaster occurs where social pressures and physical events overlap
What does the PAR model suggest
What areas could be modified to reduce the risk
Name three positives of event profiles
Compare physical processes in similar events
Allow specific management to be considered
Identify and rank hazards
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
Name 3 advantages of spearman’s rank
Shows significance of data
Proves/disproves correlation
Doesn’t assume normal distribution
Name 3 disadvantage of spearman’s rank
Can be time comsuming and difficult
2 sets of data needed
Results can be misinterpreted
What percentage of the Philippines and it’s population is at risk of multiple disasters and
60% of land
74% of population
How many events does TP have per year
10
What 3 factors increase its vulnerability
Growing population
Rapid urbanisation
Poverty increase
Where do many of the poor live
In the coast which puts them more at risk
What does TP lie on
The Pacific typhoon belt
Why are multiple hazards difficult
It drains resources and stretches ability of emergency services
What building doing standards are in Manila
8.4 earthquake proof structures
What human hazards does TP have
Measles and polio outbreaks
Name another reason why natural hazards have increased in frequency
Since 2007 landslides have been included
What factor with natural hazards is rising
Financial cost
Name 4 reasons why less people are dying
Disaster preparedness, mitigation, response, recovery
What is the difference between forecasts and predictions
Forecasts are scientific and free from personal bias whereas predictions are subjective and philosophical
Explain earthquake forecasting
Based on statistical likelihood and evidence from seismic monitoring and historical records
Long term forecasts are more reliable than short term
Name 5 ways we can possibly predict earthquakes
Seismic recurrence Magma movement models Animals and p waves Hydro chemical precursors Seismic gap theory
Name 4 ways we can predict volcanoes
Shape of volcanoes
Gas and steam emissions
Temperature changes
Harmonic tremors
What is the exam boards definition of a mega disaster
A disaster that has both regional and global impacts
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
Name two ways in which we modify volcanoes
Mitigation and engineering strategies eg bombing in Edna
Name two ways in which we modify tsunamis
Increasing coastal vegetation and building tsunami walls
Can we modify earthquakes
No
How can we reduce human vulnerability to earthquakes
Skyscrapers that sit on moving balls, retrofitting older buildings, cross bracing
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
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
What do modifications all depend on
The governance of the country
What is Parks model also known as
the disaster response curve
what is the parks model used to understand
prediction, impact and management of tectonic hazards
what is the aim of parks model
to show the effects of hazard on quality of life over a sequence of time
How many stages are in this model
5
name three advantages of this model
visually effective and easy to interpret
enables similar events to be compared
highlights significance of emergency relief
name three disadvantages of this model
generalised model
doesn’t account for differences in development
doesn’t establish capacity to respond
Name another model for disaster management
the disaster risk management cycle
what are the 4 parts of the DRMC
preparedness, response, recovery, mitigation
