Tectonics

Crust

thin, solid, outer layer of Earth

Mantle

thick, mostly solid layer of Earth

Outer core

liquid layer composed mainly of iron and nickel

Inner core

solid, dense centre made of iron and nickel

Lithosphere

crust and mantle, made up of 15 massive pieces known as tectonic plates

Asthenosphere

The thin zone of the mantle just beneath the lithosphere

Continental drift

movement of continents due to the motion of tectonic plates

Convergent (destructive)

where two tectonic plates collide, sometimes subduction occurs. Slow movement, forms ocean trenches and mountains

Divergent (constructive)

where two tectonic plates move apart

Transform (conservative)

where two tectonic plates slide past each other

Movement of plate tectonics

Convection currents circulate the mantle, hot magma rises to the surface where it cools, becoming denser and sinking back down

Fault

a break in the Earth’s surface where tectonic plates slide past each other

Epicentre

point on Earth’s surface directly above the focus

Intensity

measure of the amount of destruction caused by an earthquake

Magnitude

measure of energy released by the earthquake

Moment magnitude scale

logarithmic scale used to compare the amounts of energy released by earthquakes

Focus

point within the crust where an earthquake originates

Earthquake

shaking of the ground caused by the sudden release of energy along a fault line

Hotspot

hot magma rising through the surface, causing volcanic activity away from a fault line

Rift

zone where the lithosphere is being pulled apart

Seafloor spreading

divergent plate boundaries creating a new ocean floor

Seismic wave

vibrations along the earth’s surface generated during earthquakes

Ocean ridges

underwater mountain ranges created by tectonic plates diverging, newest crust formed closest to it

Evidence of plate tectonics

Continental drift, sea floor spreading, subduction, fossil Evidence

Primary waves

Fastest, travel through solids, liquids and gases, longitudinal

Secondary waves

Slower than P waves, travel only through solids, transverse

Surface waves

Travel along the Earth’s surface, cause the most damage during earthquakes

Ring of fire

where most of the world's earthquakes and volcanoes occur, pacific plate

Volcano

opening in the crust where molten rock, gases and ash escape from earth's interior

What’s formed when 2 continental plates divide

great rifts and valleys

What’s formed when 2 oceanic plates divide

seafloor spreading, where molten lava rises to the surface to form new plate

Normal fault

when the crust is pulled apart and one block drops down

Reverse fault

when the crust is pushed together and one block is forced upward

Repeatability

getting the same result when same person uses the same equipment under same conditions

Reproducibility

getting same result with different people, equipment, or conditions involved