Volcanoes

Question 1

Volcanic processes

Answer 1

The range of volcano types depends on the amount of energy released during an eruption
Shape relates to type of lava: basalt, andesite and rhyolite

Question 2

Andesitic lava features

Answer 2

Intermediate silica (60%)
800 to 1000 degrees
Violent, moderately explosive eruption energy
Composite cone volcanoes, subduction zones
Slow flow- travels short distance down volcanoes
Small volume flows
High viscosity (similar to honey)
Blocky lava
Subducted oceanic plate melts and mixes with seawater, lithosphere mantle and continental rocks

Question 3

Basaltic lava features

Answer 3

Located near hotspots, mid ocean ridges and shield volcanoes
Thin and runny
Gentle eruptions
1000-1200 degrees
Low silica (50%)
Low viscosity, gases escape
High co2

Question 4

Rhyolite lava features

Answer 4

650-800 degrees
High silica (70%)- very viscous
Gas (46%)
High viscosity traps gases
Thick and stiff flow
Super volcanoes or composite cone volcanoes
Melting of lithosphere, mantle and slabs of previously subducted plates

Question 5

Shield volcano facts

Answer 5

Iceland 2010 eruption
Magma of really high temperatures
Calm,less violent eruptions
Fluid magma can travel further
Basaltic lava
Constructive plate margins
Very low silica content

Question 6

Composite volcano facts

Answer 6

Made of layers of ash and lava
Sticky andesitic lava
Steep sided
Thicker magma does not travel far
Extremely explosive due to build up of pressure caused by blocked air vents
Thick and viscous lava

Question 7

Primary hazards of volcanoes

Answer 7

Pyroclastic flow
Lava flow
Tephra and ash fall
Volcanic gases

Question 8

Secondary hazards of volcanoes

Answer 8

Lahars
Jokulhlaup

Question 9

Description of Pyroclastic flow

Answer 9

Mixture of dense hot rock, lava, ash and gases ejected from a volcano

Question 10

Lava flow description

Answer 10

Streams of lava that have erupted from a volcano onto the earths surface

Question 11

Tephra and ash fall description

Answer 11

Pieces of volcanic rock and ash that blast into the air during volcanic eruptions

Question 12

Volcanic gases description

Answer 12

Magma contains dissolved gases that are released into the atmosphere during a volcanic eruption

Question 13

Lahars description

Answer 13

Masses of rock, mud and water that travel quickly down sides of volcanoes

Question 14

Jökulhlaup description

Answer 14

Heat of a volcanic eruption can melt snow and ice in a glacier- causing heavy and sudden floods

Question 15

Pyroclastic flow impacts

Answer 15

Destroy everything they touch
100km per hour
Extremely hot

Question 16

Lava flow impacts

Answer 16

If they are fast moving it poses a big threat to human life. However they destroy everything in their path

Question 17

Tephra and ash fall impacts

Answer 17

Larger pieces tend to fall near volcanoes which can cause injury or death.
Building roofs can collapse as well as start fires on the ground
Ash falls covers everything causing poor visibility and slippery roads
Engines can get clogged up

Question 18

Volcanic gases impacts

Answer 18

Most deaths are caused by the CO2

Question 19

Lahars impacts

Answer 19

Depends on: steepness of slopes, volume of material and particle size
Heavy rainfall can trigger old tephra and remobilised into mudflows
Largest can be hundreds of miles wide and can flow tens of metres per second

Question 20

Jökulhlaup impacts

Answer 20

Hazard to people and infrastructure
Floods occur very suddenly with rapid discharge of large volumes of water, ice and debris from a glacial source

Question 21

Pyroclastic flow example

Answer 21

1902 eruption of Mont Pelee in Martinique destroyed the coastal city of st Pierre
Killed near 30,000

Question 22

Lava flow example

Answer 22

1873- Lakagigar fissure, Iceland (5 months)
22% died in resulting famine