Hazards

Question 1

What type of lava do infrequently erupting volcanos release?

Answer 1

Andesitic lava

Question 2

What type of lava do frequently / continuously erupting volcanoes release?

Answer 2

Basaltic lava

Question 3

What can signify an imminent eruption?

Answer 3

Ground trembles (seismic activity)
Changes in CO2 and SO2
Ground deformations

Question 4

What is a pyroclastic flow made up of?

Answer 4

Hot rock, lava, ash and gasses

Question 5

Is a pyroclastic flow more common with andesitic or basaltic lava?

Answer 5

Andesitic lava

Question 6

How fast do pyroclastic flows move?

Answer 6

200 m/s

Question 7

How hot is a pyroclastic flow?

Answer 7

Between 350 and 1000 celsius

Question 8

What are the impacts of pyroclastic flows?

Answer 8

Death
Knocks down, buries any structure in its path
Ignite fires
Ice and snow can melt due to temps
Can cause floods and lahars

Question 9

What is a nuee ardente?

Answer 9

A large cloud that forms after an eruption, contains dense material

Question 10

What is tephra?

Answer 10

Rock fragments ejected during an eruption, large fragments land close to source, small fragments can travel large distances, small fragments can cause breathing difficulties etc

Question 11

What are the impacts of tephra and nuee Ardentes

Answer 11

Endangers aviation, damages crops, can cause health problems to humans and animals, can interrupt communication equipment

Question 12

What are lahars?

Answer 12

Ash and volcanic material mix with water to cause a large ‘mudflow’

Question 13

Where do lahars usually occur?

Answer 13

Commonly in glaciated area due to the rapid melting of the ice mixing with the material

Question 14

How fast can lahars flow?

Answer 14

Speeds up to 60 kph

Question 15

What are the impacts of lahars?

Answer 15

Crushes and buries anything in its path
Can melt snow and ice
Destroys roads
Can silt up rivers causing flooding
Can trap people in hazardous areas

Question 16

What are lava flows?

Answer 16

Flows of lava down the side of a volcano

Question 17

How fast can lava flow?

Answer 17

Can flow at speeds of 10 kph and may cover hundreds of kilometres

Question 18

What are the impacts of lava flows?

Answer 18

Knocks over and buries anything in its path
Can cause water to evaporate creating a molten shower
Can trigger a lahar
Can cause methane gas build up

Question 19

What is acid rain?

Answer 19

Gasses reacting with water vapour causing it to be acid rain when it falls back down