volcanoes

Question 1

What is volcanicity?

Answer 1

= all volcanic activities related to magma being forced up into the crust, usually at plate margins. magma at high temperatures/ pressures exploit weaknesses in the crust and may erupt onto the surface as lava.

Question 2

What is a volcano?

Answer 2

= an opening in the Earth’s crust where lava, gases, pyroclast and steam are ejected from an underground magma chamber.

Question 3

FISSURE VOLCANO

Answer 3

• constructive margins
• basaltic lava
  = lava ejected through fissures in the earth rather than a main vent. lava fills up hollows rather than building up material. this results in plateaus.
  ~ Iceland

Question 4

ACID OR DOME VOLCANO

Answer 4

• destructive margins
• acidic lava
  = acid lava solidifies on exposure to the air, producing a steep, convex cone.
  ~ Mt Pelee lava spine

Question 5

SHIELD VOLCANOES

Answer 5

• constructive margins (mid ocean ridges) or hotspots
• basaltic lava
  = runny lava exits main vent and spreads over wide areas before solidifying. this results in a cone with long, gentle slopes made up of layers of lava.
  ~ Mauna Loa

Question 6

COMPOSITE VOLCANOES

Answer 6

• destructive boundaries
• acidic lava
  = classically shaped volcanoes where alternating eruptions of ash then lava form layers. accompany violent then more gentle eruptions.
  ~ Mt Etna

Question 7

ASH OR CINDER CONE

Answer 7

• bottom of shield volcanoes & caldera’s
• no lava just ash
  = cinder and ash erupt and build up into a symmetrical cone.
  ~ Paricutin found at bottom of Mauna Loa

Question 8

CALDERA

Answer 8

• wherever
• N/A
  = build up of gases becomes extreme and huge explosions clear the magma chamber. this removes the summit as an empty chamber allows the sides to collapse inwards.
  ~ Krakatoa
  ~ Yellowstone