Lecture 1 Flashcards
In an average year, hazards require ____ people around the world to evacuate their homes.
20 million
Within North America, every location is at risk from ______ hazardous process.
at least one
What hazardous processes are the west coast, east coast, mid-continent, and all areas of NA at risk for?
West Coast: earthquakes, blizzards
East Coast: hurricanes
Mid-continent: tornadoes, blizzards, thunderstorms
All areas: drought
What processes can natural hazards arise from?
- Internal forces within the Earth
- driven by internal energy of the Earth
- eg. plate tectonics
- External forces on Earth’s surface
- driven by the Sun’s energy
- atmospheric effects (thunderstorm, snow storm, tornado)
- Gravitational attraction
- driven by gravity
- eg. downslope movement
What is a natural hazard?
-a natural process that poses a potential threat to people and property
What is a risk?
-the probability of an event occurring multiplied by the impact on people and property
What is a disaster?
-a brief event that causes great damage or loss of life (actual carrying out- carrying out of a hazard)
What is a catastrophe?
-a massive disaster
What are examples of 4 well-known catastrophes?
- Tsunami, Indonesia, 2004
- Hurricane (Katrina), New Orleans, 2005
- Earthquake, Haiti, 2010
- Tsunami, Japan, 2011
How do natural hazards differ in their potential to cause a catastrophe?
- natural hazards differ in their potential to cause a catastrophe based on the size of the area affected
- more likely to be catastrophic: tsunamis, earthquakes, volcanoes, hurricanes, floods
- less likely to be catastrophic: landslides, avalanches, wildfires, tornadoes
What constitues the impact of a hazard?
- the impact of a hazard is a function of both its magnitude (ie. energy released) and frequency
- it can also be affected by geology, land use (eg. rural or urban), population density, etc.
What is the magnitude-frequency concept?
- there is an inverse relationship between magnitude and frequency (if one goes up, the other goes down)
- low magnitude earthquakes are very frequent, high magnitude are not frequent
What provides insight on an area’s risk of hazards?
- history of the area
- maps, historic documents, journals, aerial photos
- weather and climate data
- craters (clue of meteorite), faults (earthquakes), valleys (glacier melting)
What is the geologic cycle?
- throughout Earth’s 4.6 billion year history, the materials on or near the surface have been created and modified by physical and chemical processes
- collectively, these processes are called the geologic cycle
- the geologic cycle encompasses the tectonic cycle, rock cycle, and hydrologic cycle
What is the tectonic cycle? Where is new land formed and destroyed?
- creation, movement, and destruction of tectonic plates (land)
- tectonic plates: large blocks of earth’s crust that form its outer shell; there are 14 plates (7 big which are continents and 7 small ones between)
- the process is driven by Earth’s internal energy
- new land is formed at mid-ocean ridges (two plates separate)
- land is destroyed at subduction zones (two plates come together and one goes under)
What is the rock cycle?
- a rock is an aggregate of one or more minerals
- the rock cycle refers to a group of interrelated processes that produce the three different rock types: igneous, sedimentary, and metamorphic
- igneous: comes from volcano erupting (hardened lava)
- in a given location, the types of rocks give clues to geological events of the past
Describe the stages of the rock cycle
What is the hydrologic cycle?
- the movement and exchange of water among the land, atmosphere, and oceans by changes in state
- also referred to as water cycle
- solar energy drives the movement of water among the atmosphere, oceans, and continents
- residence time of a water molecule ranges from days (in the atmosphere) to thousands of years (in the ocean)
Describe the stages of the water cycle
Describe the course theme: Hazards can be understood through scientific investigation and analysis.
- scientists observe a hazardous event and form a possible explanation for the cause
- from this explanation, a hypothesis is formed
- data is then collected to test the hypothesis
- knowing the cause allows for the identification of where hazards may occur
- knowledge of past events aids in predicting future events
What are 5 major course themes?
- hazards can be understood through scientific investigation and analysis
- an understanding of hazardous processes is needed to evaluate risk (risk, consequences)
- hazards are linked to each other and the environment
- population growth and socioeconomic changes are increasing the risk from natural hazards
- the consequences of hazards can be reduced
Describe how hazards are natural processes
- the events are natural forces
- they only become hazardous when they disrupt human activity or the environment
- these processes are not within our control
- we can’t prevent them, we can only respond tot hem
- the best solution to mitigate loss is preparation
What is a prediction vs forecast?
- prediction: a specific time, date, location, and magnitude of the event
- forecast: a range of probability for the event
How are predictions and forecasts invovled in mitigating loss?
- accurate predictions and forecasts are necessary to reduce loss
- some hazards can be predicted, many can be forecasted
How is risk calculated?
risk-=(probability of event) x (consequences)
What are consequences?
-damage to people, property, the environment, economy
What is acceptable risk?
- amount of risk that an individual or society is willing to take *subjective
- frequency of an event plays a role in determining acceptable risk
Describe how hazards are linked
- earthquakes cause tsunamis and landslides, hurricanes cause tornadoes and flooding
- some environments are linked to certain hazards (eg. some rock types are more prone to landslides- weaker rock means more landslides)
Describe the increasing risk of natural hazards
- concentration of human population creates greater loss of life in a disaster
- population growth is putting greater demand on Earth’s resources
- rapid population growth is currently occurring in most developing countries
- many people live in areas that are prone to hazards
Human population reached _____ in late 2011. ___ and ____ combined account for 1/3 of Earth’s population.
- 7 billion
- India and China
- Canada and US not growing fast, lesser developed countries growing very quickly
How are risks associated with hazards affected as human development expands?
- risks change as human development expands
- neighbourhood extend onto hillside and floodplains
- urbanization alters drainage and slopes
- agriculture, forestry, and mining can increase erosion
- In Canada, property damage from hazards is increasing but deaths from hazards are decreasing (because of better planning and warning)
Where are economic losses from disasters felt most strongly?
- economic losses much higher in developed countries
- deaths from disasters are much higher in developing countries
What is the disaster trend in Canada?
-seeing more weather disasters with climate change but death tolls are going down
What are direct vs indirect effects of a disaster?
- direct: deaths, injuries, displacement of people, damage to property
- indirect: crop failure, starvation, emotional distress, loss of employment
- indirect can linger in a lesser developed country
- mainly deal with effects in reactive ways but a higher level strategy requires a proactive approach
What is a reactive approach to hazards?
-recovery, search and rescue, providing emergency food, water, shelter, and rebuilding
What is a proactive approach to hazards?
-land-use planning, building codes, insurance, evacuation planning, disaster preparedness (drills), artificial control
What are natural service functions?
- benefits of hazardous events
- flooding provides nutrients for soil, landslides from natural dams create lakes, volcanic eruptions create new land
What is the most crucial environmental issue currently facing Earth?
- climate change
- as climate changes, the frequency of some natural processes will increase
- sea level rise from melting ice sheets will cause more coastal erosion and flooding
- warmer oceans cause more frequent hurricanes
- has become a political issue
The asthenosphere is ____
- upper mantle
- composed of hot magma with some flow
The inner core is____
-extremely hot and solid
The lithosphere is____
-thin and brittle crust (broken into 14 plates)
Describe layers of Earth’s internal structure
What is the crust? What are the two types?
- crust forms the upper part of the lithosphere and is broken into plates
- oceanic: supports an ocean- dense, thin (averages 7km thickness)
- continental: supports continent- relatively buoyant, thick (averages 30km thickness)
- movement of the plates is caused by convection currents within the mantle
An oceanic and continental plate are colliding. Which plate is going to sink below the other?
- oceanic plate will sink because it is denser
- nothing to do with thickness
What are the types of plate boundaries?
- divergent, convergent, transform
- plate boundaries do not tend to match up with the boundaries of continents or oceans
- the movement of plates causes dynamic events (earthquakes) on Earth’s surface, especially at plate boundaries
What is Pangea and evidence for it?
- continents of today were clustered into the supercontinent of Pangea 250 million years ago
- evidence for this includes current mountain ranges
- Africa pushing into NA causes Appalachian mountains (found same fossils on both sides)
- fit together like puzzle pieces
- Nova Scotia used to be attached to Morrocco
What is a divergent plate boundary?
- plates move away from each other
- new land is created at these locations
- divergence results in seafloor spreading and causes oceanic ridges to form (eg. the Mid Atlantic Ridge)
What is a convergent plate boundary?
-plates move towards each other
What creats a subduction zone vs a collision boundary?
- collisions involving oceanic and continental crust result in subduction zones: dense ocean plates sink and melt, the melted magma rises to form volcanoes
- collisions involving two continental plates results in collision boundaries: neither plate sinks, tall mountains tend to form (Himalayan mountains)
- India is pushing into Asia causing mountains to get higher
What is a transform boundary?
- plates slide horizontally past each other
- the zone along which the movement occurs is called a transform fault
- most of these faults are located beneath oceans but some are found on continents
- eg. San Andreas fault: areas west of the fault (LA, Santa Barbara, etc.) are slowly sliding to the North and eventually will break from the rest of California and slide up towards Alaska
What are hot spots?
- areas are found away from plate boundaries
- spots where magma rises up from the mantle
- magma erupting at the surface results in the formation of volcanoes
- strings of islands are usually indicative of a hot spot
- plate is moving over the hot spot so you get the strings of islands
- ex: Hawaiian islands
Which mountain chain is the site of a continent-continent collision?
- India and Asia colliding
- Himalayan mountain chain
What will happen to San Andreas fault in the future?
- will form an island up towards Alaska
- can see on map animation island on left side of NA
island arc is too buoyant to subduct so it pushes up and forms new mountain ranges
this is how BC has all the mountain ranges
