Volcanoes

Question 1

What is a pyroclastic surge?

Answer 1

A fast-moving flow of hot gas and volcanic matter that increases in speed and buoyancy when rocks are no longer present to hold it back.

Pyroclastic surges can cover greater distances in shorter time due to the buoyant gases present.

Question 2

What are Nuees Ardentes?

Answer 2

Glowing clouds or pyroclastic surges that can exceed 240 km/h due to their gas content.

Example: The 1902 eruption in Martinique resulted in widespread destruction.

Question 3

What types of solid material are included in tephra/pyroclasts?

Answer 3

All types of solid material, including:
* Lava
* Fragmented volcanic materials
* Volcanic bombs
* Cinder
* Ash

Volcanic bombs are larger than 64 mm, while cinders range from 2-64 mm.

Question 4

What size is ash typically in volcanic eruptions?

Answer 4

Less than 2 mm in size.

Ash is formed from rock debris broken up by volcanic eruptions.

Question 5

What is the primary hazard of heavy ash falls?

Answer 5

Destruction including burying roads and buildings, causing roofs to collapse, and suffocating people.

Example: The destruction of Pompeii in 79 AD and the 2010 volcanic eruption in Iceland.

Question 6

What gases are produced by volcanoes?

Answer 6

Gases include:
* Water vapor
* Carbon Dioxide
* Sulphur Dioxide
* Chlorine
* Hydrogen Sulphide
* Helium
* Carbon Monoxide
* Hydrogen Chloride

Carbon Dioxide is particularly dangerous as it is heavier than air.

Question 7

What are secondary hazards in volcanic eruptions?

Answer 7

Hazards that occur as a result of primary hazards, such as:
* Acid rain from gases mixed with water
* Flooding due to heavy rainfall

Secondary hazards affect people and the environment indirectly.

Question 8

True or False: Volcanic gases can lead to health problems.

Answer 8

True.

Gases can cause breathing problems, skin issues, and eye irritations.

Question 9

Fill in the blank: Ash falls refer to rock debris that is broken up by volcanic eruption and thrown up in the atmosphere, usually less than ______ in size.

Answer 9

2 mm.

Question 10

What is the effect of volcanic gases on water bodies?

Answer 10

Gases can mix with water, becoming acidic and leading to contamination.

This can kill aquatic life and scorch vegetation.