Volcanoes Flashcards
What plate boundaries do volcanoes form at?
Divergent and convergent plate boundaries
What is a hotspot?
A place in the centre of a plate where magma rises causing the lithosphere to melt and pushing magma through the crust to form volcanoes
Why don’t all volcanoes happen on plate boundaries?
Because there are various areas of the mantle that are hotter than others - hotspots
What does it mean when a volcano is inactive?
It won’t erupt.
What can volcanoes form?
Islands
What is the crater?
The opening of the volcano
What is a volcanic cloud?
Gas, steam and ash escaping the volcano
What is the secondary vent and cone?
An opening on the side of the volcano allowing magma to escape
What are the layers on the volcano?
Layers of ash and lava from pyroclastic flows which build up overtime forming the side of the volcano
Where and what is the magma chamber?
Located at the bottom of the volcano where hot molten rock is stored
What is the main vent?
The tunnel which the magma rises to the top of the volcano
What is lava and lahar?
Molten rock and mud flows flowing down the side of the volcano.
What are volcanic bombs?
Large pieces of rock ejected from the volcano
Why can magma escape from the secondary vent and cone?
Due to the high build up of pressure.
What plate boundary is a shield volcano formed in?
Divergent
Where do composite volcanoes form?
Convergent
What is the lava like in a shield volcano?
Runny, seeps out gently
What is the lava like in a composite volcano?
Viscous (sticky) and thick
What is the VEI?
Volcanic Explosivity Index is a measure of explosiveness of volcanic eruptions (the higher, the larger the explosion)
When did mount pinatubo ( the composite volcano) last erupt?
What was the VEI?
death toll?
Last erupted in 1991
VEI of 6
Killed 847 people
When did Queen Mary’s Peak ( the shield volcano) last erupt?
How wide is it?
What was the death toll?
Last erupted in 2004
300m wide
No-one died
