Plate Tectonic Flashcards
how is the crust divided
the crust is divided into several large pieces called plates
it is unstable because plates move
😊slowly
name the way plates move
together destructive and collision
apart constructive
past each other conservative
how many types of crust are there
2 continental and oceanic
oceanic crust
5-10km thick
dense
sinks when is subducted by continental
oldest is 180 million years old
forms constantly at constructive plate boundaries
destroyed at destructive plate boundaries
continental
25-100km less dense doesn't sink very old 3-4billion years old no crust not form cannot be destroyed
plate theories described the structure of the earth’s layers
inner core solid hot up to 5000oc outer core liquid iron and nickel mantle soft molten rock about 3000oc nickel and iron crust hard outer shell separated into plate margins
what happens inside the earth
heat from core gives convection currents in the mantle
very slow
causes plates to move
causes earthquakes and volcanoes to set off
magma
liquid rock
melted due to the earth’s core heat intensity
where do earthquakes and volcanoes happen
around plate boundaries
causes by friction of two.plates
or.molten rock magma rising to the surface of earth
why do earthquakes happen
occur due to stresses build up between the plates as one passes each other
plates are not smooth so they snag and grind each other allowing energy to.build up
when plates move seismic waves is released from energy
what is the focus
the focus is the place is where the earthquake is occurring
what is the epicentre
the epicentre is above on the surface of the earth where the epicentre resides
what is a volcano
they are mountains that can explode with violent conquences
volcanoes are landforms that are from hot liquid magma bring forced up from the earth’s crust through a vent
how many types of volcanoes are there
2
what are composite volcanoes
found ate destructive plate boundaries steep sided layers of ash and lava viscous magma cools quickly very explosive
shield volcanoes
found at constructive plate boundaries dome shape sloping sides runny magma flows a long distance gentle explosions
destructive plate boundaries
oceanic meets continental moving towards each.
dense oceanic is subducted by continental
it melts and produces andesite
sinking plate can stick to continental,
pressure builds up against friction causing earthquakes
e.g Pacific and eurasian plates
constructive plate margins
two oceanics plates move apart
new oceanic crust is created constantly in the gap as the magma cools
runny magma shield volcanoes
earthquakes due to friction as plates tear apart
n American and eurasian plates
conservative plates
plates move by either in the same or different directions
slide pass each other causing friction earthquakes
no 🌋 volcanoes
Pacific and n American plates
collision 💥
fold mountains are created
two continental plates moving towards each other
non of the plates sinks as they both have similar densities
plates buckle to form mountains e.g. himalayas
no volcano
indo-australian and eurasian plates
primary effects of tectonic hazards
these are things that happen during the tectonic hazards sure such as : buildings collapsing injuries electricity and water supplies cutbacks homelessness
secondary effects of tectonic hazards
these are things that happen afterwards such as
fires
landslides
tsunamis
