Volcanoes

Question 1

State and describe the three types of eruptions.

Answer 1

Shield volcano: spans the largest land mass, low viscosity and large amounts of magma.

Composite cone: smaller than the shield volcano, forms a small crater at the summit.

Cinder cone: smaller than the composite, wider crater at the top.

Question 2

Volcanic risk depends on _____ and _____ ?

Answer 2

EVENT:
- type
- materials
- scale
- distance/velocity of material movement

IMPACT
- extent of hazard
- land use
- ability to provide warning
- willingness to receive warning/evacuate

Question 3

What are the 3 types of lava [flows]?

Answer 3

Mafic (basaltic) lavas
(flowing, long distances)
> Shield volcanoes

Intermediate (andesitic)
> Composite cones

Felsic (rhyolitic) lavas
(shorter/thicker, explosive)
> Volcanic domes/pyroclastic flows

Question 4

What are the significance of gases (volatiles) in volcanic activity?

Answer 4

Volatiles affect mobility. They propel magma from a vent/conduit/opening.

Question 5

What are ‘Lahars’?

Answer 5

Mudflows off steep sided volcanoes. Triggered by large volumes of ice and snow melting during an eruption. Heavy rainfall saturates weathered deposits. Melting of snow caps.