Avalanche

Question 1

Define avalanche.

Answer 1

Is a rapid downhill movement of snow, ice and rocks.
Usually in mountainous environments.
They move down hill at speeds of up to 300km an hour.

Question 2

Name the 3 types of avalanches?

Answer 2

Powder.
Slab.
Wet.

Question 3

What are snow avalanches?

Answer 3

Usually powdery avalanches that start from a single point.

Question 4

What are slab avalanches?

Answer 4

Large-scale avalanches formed when a slab of ice and snow breaks away from the main ice pack.
It has immense power causing a great deal of damage.
They occur naturally and can be triggered by humans.

Question 5

Name human causes of avalanches?

Answer 5

Skiing.
Loud noses.
Tree removal.

Question 6

How can skiers trigger an avalanche?

Answer 6

They can travel over unstable snow and make it become even more unstable.

Question 7

How can loud noises trigger an avalanche?

Answer 7

Cause big vibrations and weaken the snow making it unstable.

Question 8

How can tree removal trigger or help protect from an avalanche?

Answer 8

No interception to slow down or divert snow.

No barriers for protection.

Question 9

Name physical causes of avalanches?

Answer 9

Heavy snowfall.
Steep slopes.
Temperature rising.
Heavy rainfall.

Question 10

How can heavy snowfall trigger avalanches?

Answer 10

It puts pressure on the slope and destabilises the slope.

Question 11

How can steep slopes trigger avalanches?

Answer 11

The snow will never be fully stable.

Question 12

How can temperature rising trigger avalanches?

Answer 12

It melts snow and ice.
Lubricates the slope.
Weakens the bonds.

Question 13

How can heavy rainfalll trigger avalanches?

Answer 13

Melts the snow and ice.

Snow becomes unstable and the heavy rainfall is making it heavier.

Question 14

What is an important trigger?

Answer 14

Overloading.

The weight of the snow increases until it overcomes cohesion to the snow pack underneath.

Question 15

What slope angle to most avalanches occur at?

Answer 15

25 and 400C.

Question 16

How can vibration be caused?

Answer 16

By thunder, gun shot, explosions etc.

Question 17

What natural disaster can cause avalanches?

Answer 17

Earthquakes.

Question 18

Where is the avalanche problem more severe?

Answer 18

Europe than North America due to higher population densities in the Alp mountain range.

Question 19

What are powder avalanches?

Answer 19

Often start from a single point and accumulates snow as it moves down the slope forming a snowball effect. This type is most common following heavy snowfall Without the cohesion with the snow layer underneath the snow is too heavy to settle.

Question 20

How fast can powder avalanches travel?

Answer 20

62 and 186 miles per hour.

Question 21

What are slab avalanches?

Answer 21

Most common type of winter avalanche due to the build up fresh snow.
A slab is a compact snow surface layer that can detach from a weaker snow layer underneath.
The slab slips forward as a whole block or breaks into pieces.

Question 22

What are wet avalanches?

Answer 22

Often occurs after a warm spell or during the spring thaw.
Snow becomes heavier as it begins to turn into water. Occurs frequently and are generally small and generally easier to predict than the other types.

Question 23

Name a recent avalanche in history?

Answer 23

The Cascade range, Washington (1910)
The worst avalanche disaster in the USA to date. Three snow-bound trains were swept into a canyon which killed 118 people.