Natural Hazards

Question 1

List the three energy sources for natural phenomena and what they lead to.

Answer 1

Earth’s internal heat: convection in mantle; leads to earthquakes, volcanic eruptions.

Solar energy: sun warms earth, circulation of atmosphere, oceans, evaporation determine climate; related to violent storms, floods, wildfires.

Gravitational attraction: attraction of materials towards centre of earth, rocks/soil/snow/water move downslope; attracts objects from space.

Question 2

Define a natural hazard and how it relates to probabilities.

Answer 2

Any natural process that threatens human life or property.

Probability that a specific damaging event will happen in a given time period.

Question 3

True/false: the hazard is the process itself.

Answer 3

False.

Question 4

What is a natural disaster?

Answer 4

Extreme events triggered by destructive forces occurring in nature, cause significant disruption to society.

Question 5

Natural disasters are usually rapid (seconds to weeks) and have limited _____ extent.

Answer 5

Areal.

Question 6

This event is considered to be more massive and affects a larger number of people or more infrastructure than a natural disaster. What is it?

Answer 6

Catastrophe.

Question 7

According to the Geologic Survey of Canada, there are two types of hazard. Define both.

Answer 7

Catastrophic Hazards: sudden onset, occur without much warning, loss of life and damage to property.

Hazardous Conditions: occur slowly, property damage and long term health issues.

Question 8

List the four hazardous conditions posed by climate change.

Answer 8

Sea level rise: flooding (3mm/year).

Geochemical: radiation, elements.

Permafrost thawing: increased methane.

Natural gas hydrates: frozen methane.

Question 9

List the four types of catastrophic hazards in Canada.

Answer 9

Geological: volcanoes, earthquakes, tsunamis, geomagnetism.

Climatological: hurricanes, tornadoes, blizzards, avalanches.

Multiple conditions: floods, landslides.

Extraterrestrial: impacts, solar storms.

Question 10

What is risk? How is it calculated?

Answer 10

Function of the hazard plus exposure.

Risk = Hazard Probability x Vulnerability.

Question 11

What is acceptable risk?

Answer 11

Level of risk tolerated before action is needed to reduce exposure to the process.

Question 12

What is a hazard assessment? What does it NOT do?

Answer 12

Evaluation of possibility and/or probability that threatening process can or will occur.

Does not quantify risk.

Question 13

What is risk analysis?

Answer 13

Evaluation of the probability of a hazardous process and its possible consequences.

Question 14

What are the three deadliest hazards?

Answer 14

Flooding.

Earthquake-tsunami.

Hurricanes.

Question 15

With disasters, what can you expect in more developed areas with regard to damage?

Answer 15

More costs.

Question 16

Canada has a relatively low risk for a developed country. What are four reasons that explain this?

Answer 16

Low frequency of earthquakes.

Low population density.

Less vulnerable infrastructure, good building codes.

Some emergency management.

Question 17

What are natural processes?

Answer 17

The ways in which events affect the Earth’s surface.

Question 18

What is mitigation?

Answer 18

Efforts to prepare for disasters, minimize harmful affects. Actions taken to reduce or eliminate long-term risk to human life and property from natural hazards.

Question 19

Magnitude is the amount of energy increased. How is it calculated?

Answer 19

M = 1/frequency

Question 20

What is a recurrence interval and what is important to note about them?

Answer 20

Average time between the occurrence of two events of given magnitude, historical record.

Individual events inherently unpredictable.

Question 21

The impact of an event is a function of what?

Answer 21

Magnitude and frequency.

Question 22

What is a prediction?

Answer 22

Statement of probability that an event will occur, based on scientific observation.

Question 23

What is a forecast? How does it relate to weather and earthquakes?

Answer 23

Public announcement that a hazardous event likely to occur during specific period, commonly with statement of probability.

Weather-related: specific short-term predictions.

Earthquake: less precise, long-term probability and not specific.

Question 24

Forecasts are based on what two things?

Answer 24

Data and models.

Question 25

What is the difference between a prediction and a forecast?

Answer 25

Prediction specifies whether disaster will/won’t occur at a given place, during a given time, with a given magnitude range. Forecast pertains to probability.

Question 26

What is a hindcast? What does it help define?

Answer 26

Means of testing models and evaluation uncertainty using data from past events.

Helps define magnitude limits, boundary conditions.

Question 27

In hindcasts, the longer a record is, the better. How long should weather hazard records be? Seismic hazard records?

Answer 27

Weather hazards: 40+ years.

Seismic: hundreds of thousands of years.

Question 28

Forecasting and warning can be attempted if what three elements are met?

Answer 28

Location of hazard.

Probability that an event of a given magnitude will occur.

Identifying any precursor event.