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Avalanches are exclusively composed of snow and air.
Answer: False
Explanation: Large avalanches can incorporate materials such as ice, rocks, and trees, in addition to their primary composition of snow and air.
Suffocation is one of the primary causes of death for individuals caught in avalanches.
Answer: True
Explanation: Individuals caught in avalanches can succumb to suffocation, trauma from impact with debris, or hypothermia.
Friction between the snow and the surface beneath it is a force that helps an avalanche move.
Answer: False
Explanation: Friction between the snow and the surface beneath it, along with other factors like fluid-dynamic drag, acts as a force that *resists* an avalanche's movement, rather than helping it.
In recreational settings, most avalanche accidents are caused by spontaneous, natural avalanches.
Answer: False
Explanation: In recreational settings, approximately 83% of avalanche accidents are caused by the people involved, whereas in residential or industrial settings, accidents are almost exclusively caused by spontaneous, natural avalanches.
Avalanches are differentiated from rock slides primarily due to their composition of flowing snow and air.
Answer: True
Explanation: Avalanches are distinguished from rock slides and other mass movements primarily by their composition, which consists of flowing snow and air.
What is the primary composition of an avalanche?
Answer: Primarily snow and air, potentially with ice, rocks, and trees
Explanation: Avalanches are primarily composed of flowing snow and air, but larger ones can also incorporate ice, rocks, and trees.
What is the primary cause of avalanche accidents in recreational settings?
Answer: Avalanches caused by the people involved
Explanation: In recreational settings, the primary cause of avalanche accidents is human activity, accounting for approximately 83% of incidents.
What is a key difference in avalanche triggers between recreational and residential/industrial settings?
Answer: Recreational avalanches are mostly human-triggered; residential are mostly natural.
Explanation: A key difference is that recreational avalanches are predominantly human-triggered (around 83%), while residential and industrial setting avalanches are almost exclusively natural.
What is the main difference between an avalanche and a rock slide, according to the source?
Answer: Avalanches are primarily composed of snow and air, while rock slides are composed of rock.
Explanation: Avalanches are distinguished from rock slides by their composition, which is primarily snow and air, whereas rock slides consist of rock.
Which of the following is a force that *resists* an avalanche's movement?
Answer: Fluid-dynamic drag at the leading edge
Explanation: Forces that resist an avalanche's movement include friction, fluid-dynamic drag at the leading edge, and shear resistance within the flow.
Loud noises are a common trigger for avalanches.
Answer: False
Explanation: Contrary to popular belief, avalanches are not triggered by loud sounds, as the pressure from sound waves is insufficient to initiate such an event.
The conceptual model for understanding avalanches includes terrain, weather, and snowpack as primary elements.
Answer: True
Explanation: The conceptual model developed by Fesler and Fredston identifies terrain, weather, and snowpack as the three primary elements contributing to avalanche formation and behavior.
Convex slopes are generally more stable than concave slopes in avalanche formation.
Answer: False
Explanation: Convex slopes are generally considered less stable than concave slopes due to differences in the tensile and compressive strengths of snow layers across these terrain features.
Windward slopes typically accumulate more snow and pose a higher avalanche risk than leeward slopes.
Answer: False
Explanation: Leeward slopes, being sheltered from the wind, typically accumulate more snow, forming wind slabs and cornices, thereby posing a higher avalanche risk compared to windward slopes.
Slopes steeper than 60 degrees are considered to have the highest incidence of avalanches.
Answer: False
Explanation: Slopes flatter than 25 degrees or steeper than 60 degrees generally have a lower incidence of avalanches. The highest incidence of human-triggered avalanches typically occurs on slopes around 38 degrees.
Depth hoar, or facets, are angular snow crystals that form due to rapid moisture transport along a temperature gradient.
Answer: True
Explanation: Depth hoar, also known as facets, consists of angular snow crystals that form within the snowpack due to rapid moisture transport along a temperature gradient, leading to poor bonding and instability.
Wind can stabilize snowpack by evenly distributing snow across all slopes.
Answer: False
Explanation: Wind can destabilize snowpack by transporting snow to sheltered slopes, creating unstable wind slabs, rather than evenly distributing it.
In the short term, rain can stabilize a snowpack by increasing friction between layers.
Answer: False
Explanation: In the short term, rain can destabilize a snowpack by adding weight and acting as a lubricant, reducing friction between layers.
Daytime sun exposure generally strengthens the snowpack by increasing its hardness.
Answer: False
Explanation: Daytime sun exposure can destabilize the snowpack by melting the upper layers, reducing their hardness and potentially creating weak layers.
Radiative cooling occurs on cloudy nights when the snowpack gains heat from the atmosphere.
Answer: False
Explanation: Radiative cooling occurs on clear nights when the snowpack loses heat by radiating it into the atmosphere, particularly when ambient air temperatures are cooler than the snow.
Smooth ground surfaces like rock slabs are less prone to full-depth avalanches than surfaces with boulders.
Answer: False
Explanation: Smooth ground surfaces, such as rock slabs, are more prone to full-depth avalanches than surfaces with boulders or other features that can create temperature gradients and weak layers.
The critical slope angle for the highest incidence of human-triggered avalanches is approximately 30 degrees.
Answer: False
Explanation: The critical slope angle for the highest incidence of human-triggered avalanches is approximately 38 degrees, with the highest frequency generally occurring between 35 and 45 degrees.
What external factors can trigger an avalanche?
Answer: Humans, animals, and earthquakes
Explanation: External factors that can trigger avalanches include humans, animals, earthquakes, and artificial triggers like skiers or snowmobiles.
Which of the following is explicitly stated as NOT triggering an avalanche?
Answer: Loud sounds
Explanation: Loud sounds are explicitly stated as not being a trigger for avalanches, as the pressure waves are too weak.
What slope angle is generally considered the least prone to avalanches?
Answer: Less than 25 degrees or greater than 60 degrees
Explanation: Slopes that are flatter than 25 degrees or steeper than 60 degrees are generally considered less prone to avalanches.
What is the critical slope angle for the highest incidence of human-triggered avalanches?
Answer: Approximately 38 degrees
Explanation: The critical slope angle for the highest incidence of human-triggered avalanches is approximately 38 degrees, with the highest frequency generally occurring between 35 and 45 degrees.
What is the primary element of the Fesler and Fredston conceptual model that refers to meteorological conditions?
Answer: Weather
Explanation: In the Fesler and Fredston conceptual model, 'weather' refers to the meteorological conditions that influence avalanche formation.
Convex slopes are considered less stable than concave slopes due to:
Answer: Disparity in tensile and compressive strengths of snow layers
Explanation: Convex slopes are considered less stable than concave slopes due to the disparity in tensile and compressive strengths of snow layers across these terrain features.
Leeward slopes pose a higher avalanche risk primarily because they:
Answer: Accumulate more snow, forming wind slabs and cornices
Explanation: Leeward slopes pose a higher avalanche risk primarily because they accumulate more snow due to wind deposition, forming unstable wind slabs and cornices.
What are 'depth hoar' or 'facets' in a snowpack?
Answer: Angular snow crystals that bond poorly due to temperature gradients
Explanation: Depth hoar, or facets, are angular snow crystals that form within the snowpack due to temperature gradients, resulting in poor bonding and contributing to instability.
How does wind contribute to avalanche formation?
Answer: By transporting snow to sheltered slopes, creating unstable wind slabs
Explanation: Wind contributes to avalanche formation by transporting snow to sheltered slopes, creating unstable wind slabs that can fail under load.
What is the short-term impact of rain on a snowpack's stability?
Answer: It adds weight and acts as a lubricant, reducing friction between layers.
Explanation: In the short term, rain can destabilize a snowpack by adding weight and acting as a lubricant, reducing the natural friction between snow layers.
Daytime sun exposure can destabilize a snowpack by:
Answer: Melting the upper layers, reducing their hardness
Explanation: Daytime sun exposure can destabilize a snowpack by melting the upper layers, reducing their hardness and potentially creating weak layers.
Which type of slope is generally considered less stable due to differences in snow layer strengths?
Answer: Convex slopes
Explanation: Convex slopes are generally considered less stable than concave slopes due to differences in the tensile and compressive strengths of snow layers across these terrain features.
Slab avalanches are characterized by loose, unconsolidated snow.
Answer: False
Explanation: Slab avalanches are formed from snow that has been deposited and often consolidated by wind, and are characterized by a block or 'slab' of snow that breaks away from its surroundings. Loose snow avalanches consist of looser snow.
Powder snow avalanches are the slowest type of avalanche.
Answer: False
Explanation: Powder snow avalanches, also known as mixed avalanches, form turbulent suspension currents and can reach speeds exceeding 300 km/h (190 mph). Wet snow avalanches are the slowest type.
The European avalanche risk scale ranges from 1 (Very High) to 5 (Low).
Answer: False
Explanation: The European avalanche risk scale ranges from 1 (Low) to 5 (Very High).
In the European size classification, a 'Medium' avalanche could break trees.
Answer: True
Explanation: In the European size classification, a 'Medium' avalanche is described as one that runs to the bottom of the slope and could break trees or destroy a car.
The North American Avalanche Danger Scale is used only in Canada.
Answer: False
Explanation: The North American Avalanche Danger Scale is used in both Canada and the United States to rate avalanche risk.
'Glide avalanches' are characterized by the movement of large ice chunks from glaciers.
Answer: False
Explanation: Glide avalanches are characterized by the slow, continuous sliding of the entire snowpack over the ground surface. The movement of large ice chunks from glaciers is typically referred to as an ice avalanche.
The Canadian classification for avalanche size is based on the potential destructive impact.
Answer: True
Explanation: The Canadian classification for avalanche size is based on its potential destructive impact, ranging from Size 1 (harmless) to Size 5 (catastrophic).
Slab avalanches account for approximately 90% of avalanche-related fatalities.
Answer: True
Explanation: Slab avalanches are responsible for approximately 90% of avalanche-related fatalities, underscoring their significant danger.
Wet snow avalanches are characterized by high velocity and low density.
Answer: False
Explanation: Wet snow avalanches are characterized by low velocity and high mass/density, contrasting with powder snow avalanches which have high velocity and low density.
An ice avalanche involves the movement of large ice chunks triggered by a serac collapse.
Answer: True
Explanation: An ice avalanche occurs when a large piece of ice, often from a serac collapse, falls and triggers a rapid movement of broken ice chunks.
The European avalanche risk scale's highest level, 'Very High', corresponds to level 1.
Answer: False
Explanation: The highest level on the European avalanche risk scale is 'Very High', which corresponds to level 5, not level 1. Level 1 signifies 'Low' risk.
The US classification for avalanche size uses only one scale, the R-scale.
Answer: False
Explanation: The US classification for avalanche size uses two scales: the D-scale (destructive force) and the R-scale (relative to the path).
Which of the following is NOT one of the main forms or distinct types of avalanches described?
Answer: Slush flow avalanche
Explanation: The primary forms described are slab avalanches and loose snow avalanches. Ice avalanches and powder snow avalanches (mixed snow avalanches) are also discussed, but slush flow avalanches are not among the main types detailed.
What is a characteristic of slab avalanches?
Answer: They are triggered by the collapse of an underlying weak snow layer.
Explanation: Slab avalanches are characterized by a cohesive slab of snow breaking away due to the failure of an underlying weak snow layer.
Powder snow avalanches are known for their:
Answer: Turbulent suspension currents and high speeds exceeding 300 km/h
Explanation: Powder snow avalanches, also termed mixed avalanches, are characterized by turbulent suspension currents and can reach speeds exceeding 300 km/h.
Wet snow avalanches, despite their slower speed, can generate powerful destructive forces due to their:
Answer: High mass and density
Explanation: Wet snow avalanches, while slower than powder snow avalanches, possess high mass and density, which contribute to their powerful destructive forces.
What is the highest level on the European avalanche risk scale?
Answer: Very High
Explanation: The highest level on the European avalanche risk scale is 'Very High', corresponding to level 5.
According to the European size classification, an avalanche that runs to the bottom of the slope and could break trees is categorized as:
Answer: Medium
Explanation: In the European size classification, a 'Medium' avalanche is defined as one that runs to the bottom of the slope and has the potential to break trees or destroy a car.
The North American Avalanche Danger Scale typically ranges from:
Answer: Low to Extreme
Explanation: The North American Avalanche Danger Scale is used in the United States and Canada, with levels typically ranging from Low to Extreme.
Which of the following is NOT listed as one of the nine identified types of avalanche problems?
Answer: Rock slab
Explanation: The nine identified types of avalanche problems include Storm slab, Wind slab, Wet slab, Persistent slab, Deep persistent slab, Loose dry, Loose wet, Glide avalanches, and Cornice fall. 'Rock slab' is not listed.
The US classification for avalanche size uses two scales: the D-scale and the:
Answer: R-scale (Relative to path)
Explanation: The US classification for avalanche size uses the D-scale (destructive force) and the R-scale (relative to the path).
What is a key characteristic of wet snow avalanches?
Answer: Low velocity and high mass/density
Explanation: Wet snow avalanches are characterized by low velocity and high mass/density, which contribute to their destructive power despite their slower speed.
What is the purpose of the European size classification system for avalanches?
Answer: To describe the potential destructive impact of an avalanche.
Explanation: The European size classification system is used to describe the potential destructive impact of an avalanche, ranging from 'Sluff' to 'Large'.
The starting point of an avalanche pathway typically occurs on slopes between 20 and 30 degrees.
Answer: False
Explanation: The starting point of an avalanche pathway is typically found on slopes between 30 and 45 degrees, while the track is usually on slopes of 20-30 degrees.
A saltation layer is the core of an avalanche where large snow fragments move fluidly.
Answer: False
Explanation: A saltation layer is the outer layer of an avalanche where snow fragments become small enough to behave like a fluid, potentially becoming airborne. The core involves denser flow.
The runout zone of an avalanche pathway is typically found on slopes between 30 and 45 degrees.
Answer: False
Explanation: The runout zone of an avalanche pathway is typically found on slopes less than 20 degrees, where the avalanche comes to rest. Slopes between 30-45 degrees are usually the starting point.
The 'return period' refers to the maximum speed an avalanche can reach.
Answer: False
Explanation: The 'return period' of an avalanche path refers to the frequency with which avalanches occur in a specific area, not its maximum speed.
The three main zones of an avalanche pathway are:
Answer: Starting Point, Track, Runout Zone
Explanation: An avalanche pathway consists of three primary zones: the Starting Point where it originates, the Track along which it flows, and the Runout Zone where it comes to rest.
What is the 'track' zone in an avalanche pathway?
Answer: The zone where the avalanche flows down the slope.
Explanation: The 'track' zone is the area within an avalanche pathway where the avalanche flows down the slope, typically on gradients between 20 and 30 degrees.
What does the 'return period' of an avalanche path refer to?
Answer: The frequency with which avalanches occur in a specific area.
Explanation: The 'return period' of an avalanche path refers to the frequency with which avalanches are expected to occur in that specific area.
What is the typical slope angle range for the *track* of an avalanche pathway?
Answer: 20-30 degrees
Explanation: The track zone of an avalanche pathway is typically found on slopes ranging from 20 to 30 degrees.
Ski-cutting and boot-packing are considered passive methods of avalanche prevention.
Answer: False
Explanation: Ski-cutting and boot-packing are considered *active* measures of avalanche prevention, as they involve directly interacting with and altering the snowpack to break down instabilities. Passive methods include structures like snow fences.
Snow fences are designed to increase snow accumulation on all slopes equally.
Answer: False
Explanation: Snow fences are designed to direct snow accumulation, typically building up snow around the fence and reducing it downwind, rather than increasing it equally on all slopes.
Snow sheds are artificial barriers constructed from concrete or rocks to stop avalanches.
Answer: False
Explanation: Snow sheds are large shelters built over transportation corridors to protect them from avalanches, rather than barriers designed to stop or deflect them.
Modern radar technology can monitor large areas and precisely locate avalanches regardless of weather conditions.
Answer: True
Explanation: Modern radar technology, such as interferometric radars, enables the monitoring of large areas and the precise localization of avalanches under various weather conditions, day and night.
The Rutschblock Test is used to analyze loose dry avalanche hazards.
Answer: False
Explanation: The Rutschblock Test is specifically used to analyze *slab* avalanche hazards, assessing the stability of a cohesive snow slab.
Active avalanche prevention includes building artificial barriers like avalanche dams.
Answer: False
Explanation: Building artificial barriers like avalanche dams is considered an *active* avalanche prevention measure, but these structures are designed to stop or deflect avalanches, not to stabilize the snowpack itself. Active measures typically involve direct interaction with the snowpack.
Snow sheds are primarily used to direct snow accumulation away from roads.
Answer: False
Explanation: Snow sheds are primarily used to protect transportation corridors, such as roads and railways, from avalanches by providing a shelter over the path.
Interferometric radars are used in avalanche prevention systems to manually clear snow.
Answer: False
Explanation: Interferometric radars are used in avalanche prevention systems for monitoring and early warning, not for manually clearing snow.
Which of the following is an example of an *active* measure used in avalanche prevention?
Answer: Ski-cutting
Explanation: Ski-cutting is an active measure used to break down snowpack instabilities. Passive measures include structures like snow fences.
What is the purpose of snow sheds in avalanche mitigation?
Answer: To protect transportation corridors from avalanches
Explanation: Snow sheds are constructed over transportation routes to protect them from being impacted by avalanches.
The Rutschblock Test is used to assess:
Answer: Slab avalanche hazard
Explanation: The Rutschblock Test is a method used to assess slab avalanche hazard by evaluating the stability of a cohesive snow slab.
What is the primary function of avalanche dams in mitigation efforts?
Answer: To stop or deflect avalanches from their path.
Explanation: Avalanche dams are artificial barriers constructed to stop or deflect avalanches, thereby protecting areas or infrastructure in their path.
What is the purpose of using explosives in avalanche control?
Answer: To trigger smaller avalanches and break down instabilities.
Explanation: Explosives are used in avalanche control to trigger smaller, controlled avalanches, thereby breaking down larger instabilities in the snowpack.
How do snow fences function in avalanche control?
Answer: They direct snow accumulation and reduce it downwind.
Explanation: Snow fences function by directing snow accumulation, causing it to build up around the fence and reducing it in areas downwind.
What technology is used in early warning systems to monitor unstable areas and recognize potential ruptures?
Answer: Interferometric radars and high-resolution cameras
Explanation: Early warning systems utilize technologies such as interferometric radars and high-resolution cameras to monitor unstable areas and detect potential ruptures.
What is the primary function of snow sheds in avalanche mitigation?
Answer: To protect transportation corridors from avalanches.
Explanation: Snow sheds are constructed over transportation routes to protect them from being impacted by avalanches.
Deforestation can lead to a decrease in avalanche damage.
Answer: False
Explanation: Deforestation can lead to an increase in avalanche damage, as vegetation plays a role in stabilizing slopes and intercepting snow.
The Wellington avalanche in March 1910 killed fewer than 50 people.
Answer: False
Explanation: The Wellington avalanche in March 1910 killed 96 people. The Rogers Pass avalanche, occurring three days later, killed 62 people.
During World War I, avalanches in the Alps caused fewer than 10,000 soldier deaths.
Answer: False
Explanation: During World War I, avalanches in the Alps are estimated to have caused between 40,000 and 80,000 soldier deaths.
The 'Winter of Terror' in the Alps saw fewer than 100 avalanches occur over three months.
Answer: False
Explanation: The 'Winter of Terror' in the Alps (1950-1951) involved approximately 649 avalanches over three months, resulting in around 265 deaths.
The Galtür avalanche in 1999 resulted in 15 deaths.
Answer: False
Explanation: The Galtür avalanche in 1999 tragically resulted in 31 deaths, impacting a village previously considered safe.
Climate change is predicted to increase avalanche frequency at lower elevations due to increased snow cover.
Answer: False
Explanation: Climate change is predicted to *decrease* avalanche frequency at lower elevations due to a reduction in snow cover and depth.
Warmer, wetter snowpacks are predicted to increase survival time for buried individuals due to better air circulation.
Answer: False
Explanation: Warmer, wetter snowpacks are predicted to *decrease* survival time for buried individuals due to reduced breathing capacity and higher moisture content, rather than improve air circulation.
The Galtür avalanche in 1999 occurred in a village previously considered safe from avalanches.
Answer: True
Explanation: The Galtür avalanche in 1999 was a significant event as it struck a village that was previously considered to be in a safe zone from such large-scale avalanches.
How is climate change predicted to affect avalanche frequency at lower elevations?
Answer: Decrease frequency due to a reduction in snow cover and depth
Explanation: Climate change is predicted to decrease avalanche frequency at lower elevations due to reduced snow cover and depth.
Increased 'rain on snow' events due to climate change may lead to:
Answer: Avalanche burials being more deadly due to higher moisture content
Explanation: Increased 'rain on snow' events, linked to climate change, may lead to wet avalanche cycles and potentially more deadly burials due to higher moisture content.
The Wellington and Rogers Pass avalanches of March 1910 resulted in a combined death toll of approximately:
Answer: 158 people
Explanation: The Wellington avalanche killed 96 people, and the Rogers Pass avalanche killed 62 people, totaling approximately 158 fatalities.
During World War I, avalanches in the Alps were a significant cause of death, estimated to be:
Answer: Between 40,000 and 80,000 soldiers
Explanation: During World War I, avalanches in the Alps are estimated to have caused the deaths of between 40,000 and 80,000 soldiers.
The 'Winter of Terror' in the Alps (1950-1951) was characterized by:
Answer: Approximately 649 avalanches over three months, causing around 265 deaths
Explanation: The 'Winter of Terror' in the Alps (1950-1951) saw approximately 649 avalanches over three months, resulting in about 265 fatalities.
How does climate change potentially impact the survival rate of individuals buried in warmer, wetter snowpacks?
Answer: Survival time decreases due to reduced breathing capacity and higher moisture.
Explanation: Warmer, wetter snowpacks, potentially increasing with climate change, can decrease survival time for buried individuals due to reduced breathing capacity and higher moisture content.
What is the impact of deforestation on avalanche damage?
Answer: Deforestation can lead to an increase in avalanche damage.
Explanation: Deforestation can lead to an increase in avalanche damage, as vegetation plays a role in slope stability and snow interception.
What is the primary danger posed by warmer, wetter snowpacks due to climate change?
Answer: Reduced survival time for buried individuals due to breathing difficulties.
Explanation: Warmer, wetter snowpacks, potentially increasing with climate change, pose a primary danger by reducing survival time for buried individuals due to breathing difficulties.
How might climate change affect wet avalanche cycles?
Answer: They may occur earlier in the spring due to increased 'rain on snow' events.
Explanation: Climate change may affect wet avalanche cycles by causing them to occur earlier in the spring due to an increase in 'rain on snow' events.