2.1 Earthquakes and distribution of volcanoes Flashcards
What is the core
it is found at the centre of the earth, made out of iron and nickel, it is extremely hot and under high pressure
inner core is solid and outer core is liquid
what is the mantle
surrounds the core
beneath earths crust
what is the upper portion of the mantle
weak layer called asthenosphere which can deform
What is the outermost layer of the earth
solid crust
Describe characteristics of oceanic crust
- thinner and more dense
- formed of basaltic rock
- sinks when it meets continental plate
- less than 200 million years old
Describe characteristics of continental crust
thicker
composed of granite rock
up to 3.8 billion years old
what is the lithosphere
rigid shell that differs in chemical composition, thickness and density
what is the astenosphere
upper portion of the mantle, weak layer which can deform like plastic
What causes tectonic plates to move
convection current
ridge push
slab pull
explain how convection currents cause tectonic plates to move
The hot core causes magma to rise in the mantle and sink towards to the core when it cools
Convection builds pressure and carries plates with it
explain how ridge push causes tectonic plates to move
- Magma rises as the plates move apart at constructive plate margins
- the magma cools to form new plate material
- As it cools it becomes denser and slides down away from the ridge
- This causes tectonic plates to move away from each other
explain how slab pull causes tectonic plates to move
- At desructive plate margins the denser plate sinks back into the mantle under the influence of gravity
- It pulls the rest of the plate along behind it
Where are earthquakes and volcanoes located
Plate margins such as ring of fire
On land and in sea
Earthquakes are found at all plate margins: constructive, destructive, conservative
Volcanoes, constructive and destructive
Some found at hot spots such as hawaii
