Tectonics Flashcards
What is enquiry question 1?
Why are some locations more at risk from tectonic hazards?
What is the distribution of tectonic hazards?
concentrated along plate boundaries
Ring of fire in pacific
intraplate hazards
What percentage of volcanoes happen in the ring of fire?
75%
What are the four plate boundaries?
Convergent
Collision
Divergent
Conservative
What is the structure of the earth?
lithosphere (solid, rigid)
Asthenosphere(plastic-putty texture- partially molten)
Mantle (solid, plastic)
Outer core (liquid)
Inner core (solid nickel and iron)
How hot is the earths inner core?
6000 degrees
What is slab pull?
suggests plates are pulled down into mantle through gravity and sliding
What is ridge push?
Occurs at mis ocean ridges which becomes thicker and denser as it cools causing its weight to increase and the plate is pushed down my gravity
Which plate is the convergent boundary?
When oceanic meets continental crust and one becomes subducted
Which plate is the collision boundary?
Two plates meet and push upwards
Which plate is the divergent boundary?
two plates are moving apart
Which plate is the conservative boundary?
two plates sliding past each other
What forms at a convergent plate boundary?
deep ocean trenches
fold mountains due to subduction
Underwater volcanoes (oceanic meets oceanic)
Island arcs
composite volcanoes
deep earthquakes
What forms at a divergent plate boundary?
formation of new crust
mid ocean ridges
submarine volcanoes
rift valleys
shield volcanoes
What forms at a collision plate boundary?
Fold mountains
What forms at a conservative plate boundary?
powerful earthquakes (strong and shallow)
What are intraplate boundaries related to?
associated with ancient faults such as Rhine rift valley
Solid crust cracking over millions of years
associated with smaller magnitude earthquakes
What causes volcanic hotspots?
mantle plumes (a stationary upswelling of abnormally hot rock within earths magma)
Examples: yellow stone and Hawaii
How many major tectonic plates are there?
7
How many minor plates are there?
10
How many microplates are there?
50
How do microplates cause earthquakes and tsunamis?
numerous microplates moving in different direction and at different speeds
What did tomography reveal?
revealed ‘torn’ slabs of oceanic plates as well as ‘detached’ which were suspended in the mantle
What does seismic tomography use?
P-waves and S-waves to produce a 2D and 3D image of the earth’s interior
What is mantle drag?
slow creep motion of convection currents
How fast are convection currents?
very slow, around 20mm per year with a slow creep