Plate tectonics Flashcards
Convergent/destructive plate boundary
Subduction: denser oceanic plate forced down lighter continental one.
Earthquake
Fold mountains
Magma forced upwards –> Volcanoes
Ocean trenches
Collision/convergent
Two continental crusts collide, neither can sink.
Earthquake
Fold mountains
Constructive/Divergent
Two plates moving away from each other.
Magma rises to fill the gap.
Volcanoes
Ocean ridges
Earthquakes
Passive/Conservative
Two plates slide past each other
As they move past each other, they get stuck.
Pressure built up
When released causing earthquake
Earthquake
“focus”?
The point within the Earth from which the earthquake originates.
“Epicentre”?
The point on the Earth’s surfact directly above the focus.
Characteristcs of shield volcanos
Gentle slope
Constructive/Divergent
Non-viscous lava
Continuous and non-violent eruption
Characteristics of stratovolcanoes (composite cones)
Destructive/Convergent
Steep slope
Viscous lava, ash
Explosive with dormant phases
How is an earthquake formed?
2 plates lock
pressure builds up
one plate jerks forward sending shock waves to the surface
How is a volcano formed?
At divergent/constructive margin: plates move away magma rises to fill gap team/ash ejections explosions
At convergent/destructive margin:
oceanic crust melts, friction, heat from mantle
newly formed magma lighter, rises to surface
What is crater?
Dent at top of volcano
caused by blast of eruption
What is vent?
Pipe/tube which most of magma comes up during the eruption
What is magma chamber?
Place below ground
molten rock sits + boils, waiting to erupt
Active volcano
still active
erupt frequently
Dormant volcano
temporarily inactive but not fully extinct
