Paper 1: Tectonic Hazards Flashcards
crust
surface of rock
-made from cooler, solid rock
-split into plates
lithosphere
rigid crust found between base of the crust and top of mantle
mantle`
thickest layer of earth
-made up of semi molten rock (magma)
asthenosphere
upper part of mantle
inner core
hottest part of earth
-made of iron and nickel
continental crust
-thicker
-less dense
-less likely to be destroyed
oceanic
-thinner
-newer
-more dense
-more likely to be destroyed
tectonic hazards distribution
- close to plate margins
constructive plate boundary
- move apart
-creates a gap
-movement created by ridge push
ridge push
- magma rises through gap
-heats edges of plate - creating a raised ridge at the edge of each plate.
- lava cools to create new crust
-it becomes denser, gravity weighs down on the crust pushing it away from the boundary
Most constructive plate boundaries are found
at the bottom of the oceans.
- the plates move apart,
allowing magma to rise,
forming new oceanic crust. .
Volcano formation: constructive
- gap = hot magma can rise up.
-When magma reaches the surface it gently spills out onto the edge of the plates
The lava spreads out and cools creating wide shield volcanoes.
Earthquake formation: constructive
As the newly created crust cools and slides away from the ridge, it can fracture or crack triggering lots of gentle earthquakes.
destructive plate boundary.
Two plates move TOWARDS each other
- plates meet, ocean plate subducts
Earthquake formation: destructive
- ocean plate sinks = it rubs against the plate above (friction)
- the plates gets stuck.
- Pressure builds up until the plates suddenly unstick, the energy released creates seismic waves (an earthquake)
Volcano formation: destructive
- ocean plate sinks into the mantle,
the edge melts creating lots of extra magma. - This creates pressure to build in the mantle
- forces the magma through cracks in the crust.
=eruption
subduction zone
plates meet, the thinner, denser (heavier) ocean plate subducts (sinks) below the thicker continental plate,
destructive movement caused by
- Movement is created by slab pull.
-The sinking ocean plate is pulled further into the mantle by gravity as it is colder and denser.
This pulls the rest of the plate with it.
conservative plate boundary
Two plates move SIDE BY SIDE
- at different speeds
- As the plates scrape past each other it creates friction,
- causing the plates to become stuck.
- Pressure builds up in the plates, until the plates jolt apart.
- This releases seismic waves
-no volcanoes