Tectonics Flashcards
Pangea
All of the continents were previously connected as one super continent
How are fossils evidence of the theory of plate tectonics?
Fossils of the freshwater mesosaurus are found in both south Africa and south America
How is coal evidence of the theory of plate tectonics?
Coal can be found in antarctica, it couldn’t have formed there at its current latitude, it needs tropical conditions.
How are maps evidence of the theory of plate tectonics?
Maps of the ocean floor show the 11km marianas trench in the phillipines.
Who created the continental drift theory and what is it?
1) Alfred Wegner
2)Continents move around the earth like rafts
Where are earthquakes and volcanic activity?
Plate boundaries
Why do tectonic plates move?
Convection currents from earth’s core
Convection currents definition
Hot liquid magma currents that move in circles in the asthenosphere causing plates to move
Seafloor spreading definition
Mid ocean ridges/underwater mountains form when hot magma is forced up from the asthenosphere. New crust created splits plates
Subduction definition
As new crust is created in one place its destroyed in another. As 2 oceanic plates move to eachother one slides under the other into the mantle.
Convergent plate boundaries + example
The denser oceanic plate subducts under the other plate. The oceanic plate melts in the Benioff zone. Magma forces itself up to the surface. Eg Mt St Helens Washington state USA.
Divergent plate boundaries + example
Rift volcanoes. Less explosive. Non viscous lava. Basaltic lava. Eg mid Atlantic ridge.
Describe Mt Kilauea Hawaii.
-Hawaii islands created by pacific plate moving NW over hot mantle plane.
-High heat + low pressure at the base of lithosphere melts the rock
-Magma rises through fissures forming volcanos.
-Plate moves over hotspot. Existing active volcanos moved from hotspot
-New volcanos formed
-Old volcanos cool and subside
Effusive volcanos
High temp, low viscosity, high dissolved gas content, divergent margins, low silica, narrow base
Explosive volcanos
Low temp, high viscosity, low dissolved gas content, subduction zone, high silica, wide base
Paleomagnetism
Result of the zone of magma striking the Earth’s magnetic polarity when it cools. Used to determine historic periods of tectonic activity by remaking plate boundaries.
Hypocentre
The point within the Earth where an Earthquake rupture starts
Liquefaction
Where water saturated material temporarily loses normal strength and behaves like a liquid due to the pressure of strong shaking. Occurs in saturated soils.
Primary waves
-Type of body waves
-Compression wave/longitudinal
-Moves through solid/liquid/gas
Secondary waves
-Type of body waves
-Transverse/ move up and down/side to side
-Sheering waves
Love wave
-Type of surface wave
-Moves side to side
-High amplitude
Rayleigh wave
-Type of surface wave
-Move in an elliptical motion
-Further reach
-
Surface waves
slower
large
more destructive
Why are Earthquakes dangerous?
Soil liquefaction
buildings collapsing
landslides
tsunamis
How do buildings collapse
S and L waves shake the ground violently and can cause buildings to collapse especially if weak foundations
How do tsunamis happen?
-An Earthquake, volcanic eruption or landslide happens underwater
-Water is displaced. Rises due to tectonic energy
-Gravity pulls the water down as a wave
(One side of crack goes up forcing water above that piece with in)
Water is dragged to back to sea first (drawback)
Human factors( Tsunamis)
-Power infrastructure
-Population
-Education/preparation
-Warning system
-Coastal development
-urban/rural
Physical factors(Tsunamis)
-Magnitude of earthquake/size of landslide
-Distance from epicentre
-Coastal inlet- higher wave
-Relief (flat land is worse, easier for wave)
-Timing
-Gradient of shore
-Ecosystem
-Amplitude, water column displacement,
Example of a tsunami:
Asian tsunami 2004 was caused by destructive plate boundary east of thai coastline
Hazard definition
A perceived natural event that has the potential to threaten both life an property
Disaster definition
The realisation of a hazard that causes significant impact on a vulnerable population. Over 100 affected
What makes a population vulnerable (Deggs disaster model)
Poor infrastructure
Clean water
Healthcare
Education
Warning systems
Politics
Population density
Root causes (pressure and release model)
Limited access to power, structures, resources
Political/economic systems
Dynamic pressures (Pressure and release model)
Lack of training/investment/press freedom
Rapid population change
Rapid urbanisation
Deforestation
Moment magnitude scale
Measure of the energy released by an earthquake based on the “seismic moment” of an earthquake on a logarithmic scale
Richter scale
A measurement of the height of waves produced by earthquakes on a logarithmic scale
Mercalli scale
A measurement of the impacts of an earthquake based on people’s experiences
Volcanic explosivity index
A measurement of the volume of material ejected from a volcano, height of cloud and other observations. Logarithmic scale
Limitations of hazard event profiles
Don’t show human factors like capacity to cope
Limitation of mercalli scale
Can be generalised or exaggerated
Limitation of richer scale
Doesn’t look at duration/physical environment/context
Resilience definition
The ability of a community/government/society to prepare for, deal with and recover from hazard
Risks in San Francisco
-San Andreas fault
-dense population
-Flat land - - > liquefaction
-Tsunami risk
San fransicso resilience
-Quake proof buildings
-Higher income–> repair costs
-Response plans
-Education / training
-Stable gob
Haiti port au Prince risk
-Make shift slums not reinforced
-Steep land so buildings will collapse
-No preparation / education
-Unstable corrupt gov
-2/3 below poverty line
2015 Nepal earthquake impacts
-9000 killed
-800000 houses destroyed
-$8 billion damages
-Loss of tourism
-500000 homeless
2010 Chile earthquake impacts
-214 killed
-Electric/water/phone lined cut
-Flights diverted
-Infrastructure damaged
Haiti 2010 earthquake impacts
-7 magnitude
-220 000 killed
-Poorest in W hemisphere
-Cholera outbreak 216000 caught it
-360000+ injured
Nyiragongo eruption tectonic setting
-Most destructive effusive eruption
-Steep sloped volcano
- layers of hardened lava, ash and rocks
-Congo–> Goma
-lava lake in summit
-faults and plates stretched as they move apart
-Divergent boundary nubian and somali plate
-low viscosity basaltic lava
37kmh lava flows
Nyiragongo social impacts
125000 homes destroyed by lava
200+ killed by c02 poisoning + lava
40000 evacuated
Hygenine problems+water shortage
Looting in Goma
120000 homeless
Cholera
Nyiragongo economic impacts
80% of AIRPORT airstrips covered in lava
Business + shops destroyed
Nyiragongo environmental impacts
Crops and livestock destroyed by laba
Volcanic gases caused acid rain damaging land
Nyiragongo short time management
-Regugee camps set up
-Oxfam 33 tonnes water + cleansing equipment
-$35 million aid
-shelters made from scrap metal
Emergency vaccines WHO
UN 260 tonnes food a week
Long term management nyiragongo
-Officials retrained with evacuation plans and communities to target
-evacuation drills
Leaflets info
Lava lake monitored
Hazard event profile factors
Magnitude
Speed of onset
Duration
Areal extenr
Spatial predictability
Frequency
Physical factors of 2004 Indian ocean tsunami
Low lying coastlines
Epicentre close to communities
Large tsunami
Human factors of 2004 Indian ocean tsunami
Densely populated coastlines
Mangrove forests cut down so less natural protection
LICs didn’t have resources for protection
Social impacts of 2004 Indian ocean tsunami
120 000 Thai workers lost jobs
60% of Sri Lankan industrial infrastructure gone
70% of some villages killed
1500 villages in sumatra destroyed
Economic impacts of 2004 Indian ocean tsunami
Us10 billion dollars
Thai tourism lost 25 million in a month
Fishing tourism farming industries
Jetties washes away
Environmental impacts of 2004 Indian ocean tsunami
Vegetation and top soil remobed
Agricultural soil contaminated
Ecosystems like wetlands damaged
Freshwater supplies contaminated
Management of 2004 Indian ocean tsunami
Warning systems electronic sensors
Education
Disasters emergency comitee spent over 40 million dollars in Sri Lanka and indonesia
Evacuation shelters
Social impacts of 2011 Japan tsunami
-6000 injured
-16000 killed
-50000 missing
-46000 buildings destroyed
-300 hospitals damaged
-fukushima nuclear meltdown
Economic impacts of Japan 2011 tsunami
Airports famaged
Fukushima
Railways damaged
360 billion dollars
Environmental impacts of 2011 Japan tsunami
Ecosystems
Groundwater contamination
Gases stored in insulation released
Cause of Japan 2011
Eurasian, pacific and phillipine plates
7.2 on richter scale
Pacific plate went under
Eurasian plate lifted 9m
Epicentre underwater causing tsunami
Water 500mph
Why aren’t all statistics trustworthy?
Deaths may be from hazard itself or secondary effects or long term effects
Remote locations aren’t recorded eg myanmar in 2004
False claims to get more money
Thsiland downplayed consequence to protect tourism
Drought in the Philippines
Can happen when wet season hasn’t brought enough rain to last dry szn. Decreased HEP
Volcanic activity in the Philippines
Eg mt pinatubo 800 killed $700 million
25 volcanoes in the country
Deforestation reduced interception
Flooding in the phillipines
Happens after typhoons
Happens after tdunamks
Damage to properrt
2010 450 000 displaced
Governance definition
The process by which a country is run
Example country with good governance
Iceland
How did Iceland demonstrate good governance after te eyja volcano in 2011
700 locals evacuated
Seismic proof infrastructure
Planned evacuation routes
Gov promoted tourism
Education + informed population
Example country of bad governance
Haiti
How does Haiti demonstrate bad governance
Corruption and political volatility
Weak government
25 % in extreme poverty
Relies on other countries for help
Military take over
Mitigation definition
Strategies to avoid, delay or predict hazard events through preparing for the hazard
Economic governance
Decision making that impacts economic activities like jobs business trade. Impaxts equity poverty and quality of life
Political governance
Decision making to create policies eg planning and reduction of natural disasters
Administrative governance
System of policy implementation and needs good national and local governance. Functioning enforcement. Vulnerability monitoring. Safety standards
Multi hazard zone example
Philippines
What can be monitored for volcano prediction?
Earthquakes, ground movement, water chemistry, rock chemistry, volcanic gas
How can you modify the loss of a disaster?
-Give aid to poor people/countries
-Give insurance to reach people/countries
How can you modify vulnerability in a disaster?
-prediction/warning eg Indian ocean warning system
-preparedness
-Education
-Land use planning
How can you modify the event? (earthquakes)
Can’t control Seismic activity to focus is on making earthquake proof buildings and retrofitting existing ones. Eg San Francisco
How can you modify the event? (Volcanoes)
Lava can be diverted or chilled with water. Eg Heimay
How can you modify the event? (Tsunamis)
Coastal defences like sea walls and mangroves.
Limited evidence on effectiveness
Modify cause of event
Only possible for small scale hazards. Environmental control
What were the problems with the aid response in Haiti?
-Public institutions sidelined by well meaning organisations that rushed in
-90% of funding went to non Haitan organisations
-International donors didn’t want to give money directly to Haitan organisations
-Little access to sanitation health education
Parts of the hazard management cycle
Prevention and mitigation
Preparation
Response
Recovery
Parts of the hazard management cycle
Prevention and mitigation
Preparation
Response
Recovery
Key players
Local people, architects, local gov, insurers, national gov, NGOs, Educators, IGOs, Scientists, Constructors
What do local people do as key players
Being prepared and following advice. They didn’t do this in Nyiragongo
What do architects do as key players
Design earthquake proof buildings
What do local government do as key players?
Try to enforce building restrictions eg in vesuvius Italy
How are insurers key players
Paying out those with insurance eg after Japanese tsunami
How are national government key players
Co ordinating response
Land use zoning
How are NGOs key players
Help/hinder with response eg in Haiti they hindered
How are educators key players
They teach what to do in a earthquake eg GreatShakeout
How are IGOs key players
Bringing countries together to learn from mega disasters
How are scientists key players
Predicting eruption. Tracking ask cloud eg Eyja Iceland
Scientists as key players L’aquila example
-6.3mag 300 killed, Italy
-6 scientists + ex gov official arrested
-guilty of manslaughter due to failing to predict earthquake
-later released.
This shows misunderstanding of earthquake science which led to their conviction
