Tectonic Impacts Flashcards
What are the characteristics of continental plates?
40-65km thick, less dense 2.7 g/cm, light coloured felsic rocks, granite
What are the characteristics of oceanic plates?
3-15km thick; dense 3 g/cm, dark coloured magic rocks, basalt and gabbro, 175 million years old (young)
What is the igneous rock type at a divergent boundary?
Basaltic (mafic)
What is the igneous rock at an oceanic to oceanic convergent boundary?
Basaltic early and as it matures andesite
What is the igneous rock type at oceanic to continental convergent boundary?
Andesite
What is the igneous rock type at a continental to continental convergent boundary?
Granite (placed as plutons)
Describe the volcanic activity at a convergent boundary
Andesitic volcanism, magma rich in silica and high viscosity
Describe volcanic activity at a divergent boundary.
Basaltic lava low in silica and low in viscosity
What are the hypothesis’ which drive plate movement?
Convection, gravity, ridge push (subduction) and slab pull (sea floor spreading)
An example of an oceanic divergent boundary
The mid Atlantic Ocean ridge
An example of a continental divergent boundary
Great Rift Valley in Africa
An example of an ocean to ocean convergence
Tonga where the pacific plate is being sub ducted beneath we the Philippine plate
An example of ocean to continent convergence
Nazca plate and South America plate
Example of continent to continent convergence
Himalayas (fold mountains)
Example of transform boundary
San Andreas Fault
When did the evolution of Australia start?
3800 million years ago in the age of archea
Which two cratons begun the growth of Australia?
Pilbarra and Yilgarn
How was the east formed?
Subduction zones, volcanic activity caused belts, these were filled in by sediments and compression forces resulted in mountain building (the great dividing range)
Where was the last area of growth?
The Sydney basin cratonised by the end of the Triassic
What are the names of the two super continents?
Rodinia and Pangea
Name the Australian plate and those surrounding it
Indo-Australian plate
Eurasian to the north
Pacific to the east
African to the west
Describe the plate movements of the surrounding plates.
Convergent north with pacific
Divergent south with Antarctic
Transform to the east
Identify the hazards associated with earthquakes
Ground motion
Tsunamis
Collapse of structures
Identify the hazards associated with volcanoes
Poisonous gases
Ash flows
Lahars
Lava flows
Name two methods of earthquake prediction
Laser beams detect plate movement
Radon gas escapes from cracks in the earths crust
Name two methods for volcano prediction
Seismology - tracking rise of magma and it’s movement along fissures
Tilt metre - laser beam sensor measures changes in ground elevation
Describe the physical characteristics of a volcanic region
Mountainous, high temperature lavas
Describe the chemical characteristics of a volcanic region
Soils rich in phosphates, mostly water vapour and some carbon dioxide, minor levels of sulphur, chlorine and fluorine
Describe the biotic features of a volcanic region
Volcanic soil fertile so wide distribution and abundance of plants
Limited animals due to lava and pyro clastic flows, gases and high temperatures
Reasons for continued research into disaster prediction
Lives saved, possessions, scientists gain greater understanding
Reasons against continued research into disaster prediction
Costly, wastage of resources? List of technologies exhausted?
Describe the 2010 Canterbury Earthquake
Magnitude 7.1 40km west of Christchurch city
Originated along the alpine fault, where the indo-Australian and pacific plate meet at a transform boundary
Country highly susceptible to reoccurring earthquake activity
Future - early warning systems, increased building restrictions, safety tips on infomercials
Describe the impacts of volcanic eruptions on climate
As the gases hit the stratosphere it impacts global climate
Local climate - darkness, rainfall, lightening
Carbon dioxide heats as a greenhouse gas
Sulphur dioxide as an aerosol cools
