312 2024 notes

What is a natural hazard?

Geophysical processes that can impact human life and property.

Define risk in the context of natural hazards.

Vulnerability, mechanisms for hazards.

What is a hazard?

Probability that a specific hazardous event will happen in a given time frame.

What does vulnerability refer to?

Susceptibility to a given hazard based on exposure.

How do human choices affect vulnerability to hazards?

Humans have a role in their vulnerability by deciding their lifestyle and the spaces they inhabit.

What is the risk equation?

Risk = (Hazard * Vulnerability) / Capacity.

What are the steps in the natural hazards approach?

1. Assess, 2. Mitigate, 3. Prepare, 4. Respond, 5. Recover.

What is the elastic rebound model in earthquakes?

Shear stress released at faults causes rocks to spring back as they let go.

What is the hypocentre/focus of an earthquake?

The point location where fault rupture initiates within the crust.

Differentiate between the epicentre and hypocentre.

The epicentre is the spot above the hypocentre on the surface.

What are body waves in earthquakes?

P-waves (compression, good energy transfer) and S-waves (shear, slower, no liquids).

What are surface waves?

Waves that travel on the surface, including Love waves and Rayleigh waves.

What measures the shaking felt at a specific point during an earthquake?

Intensity.

What scale is used for measuring earthquake magnitude?

Richter scale.

What is the Volcanic Explosivity Index?

Measures volcanic eruptions' explosivity, type, plume height, frequency, and tephra amount.

What is a tsunami?

A large sea wave caused by underwater seismic disturbances, such as earthquakes.

What is the difference between a tsunami and wind-blown waves?

A tsunami has a long wavelength and wave run-up, while wind-blown waves have shorter wavelengths and wave run-up.

Name two types of volcanic eruptions based on magma composition.

Felsic (higher Si and viscosity) and mafic (lower Si and viscosity).

What are primary hazards of a volcano?

Forces that directly injure/kill people, property, and habitats.

What are pyroclastic flows?

Avalanches of volcanic rocks, ash, and gases that quickly spread.

What is a lahar?

Fast-moving flows of volcanic debris and water.

What is the Saffir-Simpson scale used for?

To classify hurricane intensity based on wind speed.

What is the relationship between climate change and tropical cyclones?

Overall number of cyclones may decrease, but intensity and precipitation amount may increase.

What are the main components of a wildland fire?

Fuel, oxygen, and heat.

How does slope affect fire behavior?

Fire moving upslope enhances pre-ignition and intensifies fire.

What types of hazards are associated with wildfires?

Hydrophobic soil layer, lack of vegetation, and reduced air quality.

What is a critical burial in avalanche safety?

When the head is buried beneath snow, obstructing breathing, with a 52% fatality rate.

Describe wet vs dry avalanches.

Wet avalanches move slowly with no cloud, while dry avalanches are fast with a dust cloud and are usually triggered by people.

What is a natural hazard?

Geophysical processes that can impact human life and property.

Define risk in the context of natural hazards.

Vulnerability, mechanisms for hazards.

What is a hazard?

Probability that a specific hazardous event will happen in a given time frame.

What does vulnerability refer to?

Susceptibility to a given hazard based on exposure.

How do human choices affect vulnerability to hazards?

Humans have a role in their vulnerability by deciding their lifestyle and the spaces they inhabit.

What is the risk equation?

Risk = (Hazard * Vulnerability) / Capacity.

What are the steps in the natural hazards approach?

1. Assess, 2. Mitigate, 3. Prepare, 4. Respond, 5. Recover.

What is the elastic rebound model in earthquakes?

Shear stress released at faults causes rocks to spring back as they let go.

What is the hypocentre/focus of an earthquake?

The point location where fault rupture initiates within the crust.

Differentiate between the epicentre and hypocentre.

The epicentre is the spot above the hypocentre on the surface.

What are body waves in earthquakes?

P-waves (compression, good energy transfer) and S-waves (shear, slower, no liquids).

What are surface waves?

Waves that travel on the surface, including Love waves and Rayleigh waves.

What measures the shaking felt at a specific point during an earthquake?

Intensity.

What scale is used for measuring earthquake magnitude?

Richter scale.

What is the Volcanic Explosivity Index?

Measures volcanic eruptions' explosivity, type, plume height, frequency, and tephra amount.

What is a tsunami?

A large sea wave caused by underwater seismic disturbances, such as earthquakes.

What is the difference between a tsunami and wind-blown waves?

A tsunami has a long wavelength and wave run-up, while wind-blown waves have shorter wavelengths and wave run-up.

Name two types of volcanic eruptions based on magma composition.

Felsic (higher Si and viscosity) and mafic (lower Si and viscosity).

What are primary hazards of a volcano?

Forces that directly injure/kill people, property, and habitats.

What are pyroclastic flows?

Avalanches of volcanic rocks, ash, and gases that quickly spread.

What is a lahar?

Fast-moving flows of volcanic debris and water.

What is the Saffir-Simpson scale used for?

To classify hurricane intensity based on wind speed.

What is the relationship between climate change and tropical cyclones?

Overall number of cyclones may decrease, but intensity and precipitation amount may increase.

What are the main components of a wildland fire?

Fuel, oxygen, and heat.

How does slope affect fire behavior?

Fire moving upslope enhances pre-ignition and intensifies fire.

What types of hazards are associated with wildfires?

Hydrophobic soil layer, lack of vegetation, and reduced air quality.

What is a critical burial in avalanche safety?

When the head is buried beneath snow, obstructing breathing, with a 52% fatality rate.

Describe wet vs dry avalanches.

Wet avalanches move slowly with no cloud, while dry avalanches are fast with a dust cloud and are usually triggered by people.

What is an avalanche?

A rapid flow of snow down a sloping surface, initiated by triggers like weather, terrain, or human activity.

What are wet avalanches?

These are slower-moving, often occurring during or after rainfall, and don't typically form a powder cloud.

What are dry avalanches?

Avalanches that move rapidly, creating a visible dust cloud, often triggered by human activity or sudden changes in snowpack.

What defines a critical burial in avalanche scenarios?

This is a burial where the victim's airway is obstructed by snow, leading to a high risk of asphyxiation.

What are the key factors contributing to avalanche formation?

Factors such as slope angle (typically 30-45 degrees), snowpack structure, weather conditions, and triggers like skiers or explosives.

What does 'capacity' mean in the context of the risk equation?

The capacity of a community to reduce or cope with the impacts of hazards. It involves infrastructure, resources, and skills.

What is the hypocenter (or focus) of an earthquake?

The specific location within the Earth where the rupture of the fault begins during an earthquake.

What is the epicenter of an earthquake?

The point on the Earth's surface directly above the hypocenter of an earthquake.

What does hazard assessment involve?

A comprehensive examination of potential dangers, involving data gathering and modeling to predict hazard characteristics.

What does hazard mitigation entail?

Strategies and actions aimed to lessen the effects of hazards, such as building codes, land-use planning, and engineering solutions.

What is hazard preparedness?

Readiness actions taken in anticipation of a hazard, including education, early warning systems, and emergency response plans.

What does hazard response refer to?

Immediate activities taken during a hazard to save lives, reduce impacts, and provide aid.

What does the recovery phase involve in hazard management?

Short- and long-term actions to return the affected area to its original state, including repair, reconstruction, and economic recovery.

How do earthquakes initiate and propagate?

Fault rupture initiates at the hypocenter, releasing energy in seismic waves that propagate outwards.

How does the Richter scale function?

The Richter scale uses a logarithmic scale to measure earthquake magnitude based on seismic wave amplitude.

How do surface waves cause destruction?

These waves shake the ground vertically and horizontally, causing damage to structures.

How does the Volcanic Explosivity Index combine eruption characteristics?

The VEI combines eruption plume height, volume of ejected material, and eruption frequency, providing a comprehensive explosivity measure.

What are the prominent characteristics of tsunamis?

Tsunamis have long wavelengths, high speeds, and are caused by the displacement of large volumes of water.

What are the effects of pyroclastic flows?

These are hot, high-speed flows of volcanic material, capable of causing widespread destruction and fatalities.

What risks do lahars pose?

Mudflows consisting of volcanic ash, debris, and water, which can inundate valleys and cause significant property damage.

How do tropical cyclones relate to climate change?

Increased sea surface temperatures can intensify tropical cyclones, potentially leading to stronger and more destructive storms.

What are the different parts of a wildfire?

The sides of a wildfire burn slower than the head of a wildfire.

How does topography influence wildfire behavior?

Steep slopes increase fire spread rates, while terrain features affect fire behavior through wind patterns and fuel distribution.

What are the characteristics of wet avalanches?

These are avalanches containing liquid water, move slower, and typically occur during warmer conditions.

What are the characteristics of dry avalanches?

These are rapid snow movements that create a powder cloud and are often triggered by human activity.

What factors influence avalanche formation?

Avalanche formation is influenced by factors such as slope angle, snowpack structure, weather, and triggers.

What is meant by 'resilience' in the context of natural hazards?

It refers to the ability of a system or community to absorb the effects of a hazard by adapting and recovering.

What is the significance of an earthquake's hypocenter?

The location where the breaking of a fault occurs, initiating the seismic waves of an earthquake.

Why is the epicenter important in understanding earthquake impacts?

It's the point on the Earth's surface directly above the focus, which usually experiences the greatest impact from an earthquake.