Earthquakes And Volcanoes

Question 1

What are pyroclastic flows?

Answer 1

Very hot solid material can travel rapidly down valleys and slopes. It is imposible for people to escape so they can be responsible for many deaths.

Question 2

What are mudflows?

Answer 2

These from when ash mixes with water and travels down river valleys. They are very destructive because mud is much denser than water.

Question 3

What are volcanic gases?

Answer 3

Carbon dioxide is a dense, non-toxic gas that can flow downhill, causing suffocation. Other gases that are poisonous can burn or cause lung disease.

Question 4

Describe the shape and structure of a composite volcano

Answer 4

Steep sided symmetrical cone shape
Tall with narrow base
Alternative layers of acid lava and ash
Lava may cool inside the vent so the next eruption is very explosive to remove the plug
Subsidiary cones and vents form e.g. mount Etna, Mount St. Helens

Question 5

Describe the shape and structure of a shield volcano

Answer 5

Gentle slopes and wide base
Frequent eruptions of basic lava
Lava flows more easily, travels longer distances before cooling
Usually non-violent 
Less viscous
E.g. Mauna Loa on the Hawaii islands