1. Geological Natural Disasters

Question 1

How does an effusive eruption occur?

Answer 1

It occurs when hot, runny basalt magma reaches the surface.

Question 2

How does an explosive eruption occur?

Answer 2

occurs when cooler, more viscous
magma (such as andesite) reach the
surface

Question 3

Does an effusive eruption flow downhill easily?

Answer 3

Yes

Question 4

Does an explosive eruption flow downhill easily?

Answer 4

No

Question 5

What boundary is common at an effusive eruption?

Answer 5

A divergent boundary

Question 6

What boundary is common at an explosive eruption?

Answer 6

A convergent boundary

Question 7

What does ground motion mean?

Answer 7

The Earth’s shake as the seismic
waves is released.

Question 8

What does liquefaction mean?

Answer 8

Saturated or partially saturated soil at
or near the ground surface loses
strength in response to strong ground
shaking

Question 9

What is a landslide?

Answer 9

A collapse of a mass of earth or rock
from a mountain or cliff

Question 10

When does a tsunami occur?

Answer 10

Occur when displacement of the sea
floor displaces the water above it,
generating large waves

Question 11

What is a flood?

Answer 11

A rising and overflowing of a body of water especially onto normally dry land.

Question 12

What is an ash eruption?

Answer 12

An explosive
eruption occurs increasing the force of hot,
expanding gases violently enter the
atmosphere

Question 13

What is a lava flow?

Answer 13

Streams of molten
rock that pour or
ooze from an
erupting vent.

Question 14

What is a Lahar?

Answer 14

A mixture of volcanic material and water that
forms a mudflow.

Question 15

What is Poisonous gas emissions

Answer 15

Varied mix of
gases in any
volcanic eruption
→ eg, sulfuric
acid, hydrogen
sulfide, hydrogen
chloride and
hydrogen bromide

Question 16

What is a hazard?

Answer 16

A threat (natural or human) that has the POTENTIAL to cause loss of life, injury,
socio-economic disruption or environmental degradation

Question 17

What are some hazards associated with Ash eruptions/falls?

Answer 17

Abrasive fine particles can
enter the lungs and irritate the
eyes of animals and humans

• Ash fall may smother plant
  life, contaminate water,
  reduce visibility and
  accumulate on buildings,
  causing them to collapse

Question 18

What are some hazards associated with Lava flows?

Answer 18

Devastating effects on local
communities → burying,
crushing, or burning objects in
their paths
- Fires started

Question 19

What are some hazards associated with Lahars?

Answer 19

Erodes life/objects in its path,
taking anything and everything
with it and gaining speed (up to
60km/h or more)
- Many volcanic deposits are
acidic and can affect soil and
river systems for many years

Question 20

What are some hazards associated with Poisonous Gas Emissions?

Answer 20

Damaged eyes & mucous
membranes
- Carbon dioxide = global warming,
Sulphur dioxide = global cooling,
ozone destruction & polluted air
(volcanic smog)
- death
- can leak into the water

Question 21

What is viscosity?

Answer 21

Viscosity is a measure of a fluid’s resistance to flow (opposite to fluidity).