Chapter 4- Volcanoes Flashcards
Define volcanoes.
Openings or cracks in the earths crust through which magma,ash, cinder and gases erupt or pour
How are volcanoes caused?
When plates collide or separate
How are volcanoes formed?
- magma seeps up from magma reservoir in mantle through cracks or vents in crust
- pressure builds near surface causing violent eruption that fires ash, cinder and gas into the sky
- lava flows out of crater at top of mountain and down sides
- lava cools and hardens
- layers of lava and ash build up to form cone-shaped volcano with crater on top
Define crater.
The mouth of a volcano from which lava, ash, cinder and gases escape
Define vent.
The crack in the surface of the ground from which the volcano emerges
Define magma chamber.
In mantle
Where magma comes from
Define magma.
Molten rock while under ground
Define lava.
Molten rock above ground
What is a secondary volcano?
A smaller volcano that breaks out on the side of a volcano
Define ridge.
Long line of mountains
What is the mid Atlantic ridge?
A series of ocean ridges
How is the mic Atlantic ridge being formed?
North american and eurasian plates separating.
-> seafloor spreading
As plates separate magma seeps into cracks in crust creating ridges
Some form volcanic island eg Iceland
Name a volcano in iceland.
Mt hekla
What geothermal action is found in Iceland?
Geysers(throw up jets of hot water and steam)
Geothermal springs
What are the advantages of geothermal springs?
Hot water used for washing and central heating
most houses heated by geothermal water
Electricity generated using steam
What happened in Iceland in 2010?
Eruptions from a volcano caused huge ash clouds, some rising up to 9km in sky
-> disrupted european air travel
What is the pacific ring of fire?
Place where plates meet
Number of active volcanoes in area eg mount st Helen’s US
What are the 3 types of volcanoes?
Active
Dormant
Extinct
List advantages of volacanoes.
Fertile soils created from lava breakdown
Geothermal springs provides hot water and central heating
New land formed
Tourists visit volcanoes and towns destroyed by them or distinctive landscape created by them
List disadvantages of volcanoes
People killed Towns destroyed Farmland destroyed Lahars cause damage Ash cloud
Name an example or result of volcanic activity in Ireland
Antrim plateau
giants causeway
slemish mountain
