tectonics Flashcards
(58 cards)
what are convection currents
super hot magma rises as its less dense and as it begins to cool it then sinks due to it being more dense.
what is the slab pull theory
the more dense crust will be pulled under the less dense crust. this causes the denser crust to melt due to the hot magma.
what is palaeomagnatism
as the plates move apart magma rises to fill the gap thats been created. it then cools and forms new crust
what is sea floor spreading
when plates move apart under the sea and new magma flows to fill the gap. this causes the seafloor to get wider.
what is subduction
when the denser crust is pulled under the less dense crust. the pressure and heat cause it to melt by subduction.
what is a destructive plate boundary
this is when two plates are moving towards each other
what can form at destructive plate boundarys
folded mountains can occur, volcanoes and earthquakes.
what is a collision margin
this is where two crusts fold up against eachother as they have the same density.
what can occur at collision plate margins
folded mountains and an enormous tectonic uplift.
what is a constructive margin
this is where two plates are moving apart. this releases pressure which causes the magma to melt
what can occur at constructive margins
volcanos occur due to the melting magma rising and also earthquakes can occur when pressure builds up at fault lines.
what two landforms are formed from constructive margins
ocean ridges and rift valleys.
what is a conservation margin
this is where two plates are trying to move past each other
what can occur at conservation margins
earthquakes can occur
what are the four plate margins
- destructive
- collision
- constructive
- conservative
where do earthquakes and tsumanis occur
they occur near plate boundarys
how do earthquakes occur
earthquakes occur due to a build up and the sudden release of pressure at all four plate margins
where do the majority of earthquakes occur
they occur at the edge of the pacific plate particularly around indonesia, japan and the Philippines.
what are earthquakes called if they occur in the middle of plates
these are known as intraplate earthquakes
why might intraplate earthquakes occur
they may occur due to old fault lines moving into their resting position and also new fault lines developing.
what are the three differnnet waves that occur due to an earthquake.
- primary waves
- secondary waves
- love waves
what are primary waves
primary waves move fast horizontally. they can travel through solids liquids and gasses and dont cause much damage.
what are secondary waves
secondary waves are slower moving vertical vibrations. they can only travel through solids and cause more damage than primary waves.
what are love waves
love waves are also horizontal moving put are at a right angle to primary waves. they are surface waves and can only travel through solids. these waves create the most damage.
