Week 1 Flashcards
annually, how many people are forced to evacuate their homes due to hazards?
20 million – don’t need to know just know a lot LOL
what are the types of hazards experienced in North America? classify them based off geographical location
west coast
— earthquakes
— landslides
east coast
— hurricanes
mid-continent
— tornadoes, blizzards, snowstorms
all areas
— droughts
give examples of hazards that pose a risk to both humans and the environment
oil spills
ozone depletion
acid rain
nuclear meltdown
airplane crash
infrastructure failure (collapsed bridges) / infrastructure aging out
what are the main processes in which natural hazards can arise?
internal forces within the Earth
— plate tectonic and mantal underneath the core
external forces on Earth’s surface
— sun’s energy - heating up land and water
— atmospheric effects such as tornadoes
gravitational attraction
— force of gravity, e.g. downslope movement
what is a hazard?
a process that poses a potential threat to people or the environment
a potential threat, not so much an event
what is risk?
the probability of an event occurring multiplied by the impact on people or the environment
all about the probability
what is a disaster?
a brief event that causes great property damage or loss of life - a carried out hazard
dis = negative
aster = astronomy
—- thought to be caused by bad alignment
what is a catastrophe?
a massive disaster
what determines the impact of a hazard?
it is a function of both its magnitude (e.g. energy released) and frequency
it can also be affected by other factors such as geology, land use, and population density among other that also affect the 2 variables
what is a function?
function means there is a relationship between 2 variables!
what does the magnitude-frequency concept say?
there is an inverse or negative relationship between magnitude and frequency
as magnitude goes up, the frequency goes down
8 is not very frequent, but 2 is very frequent
where do we get information or data from to understand or hazards?
historic documents, journals, aerial photos
weather and climate data
craters, faults, or valleys
i.e. valley = a glacier was there or there may have been flooding
what are the 3 cycles that make up the overall process called the geologic cycle?
tectonic cycle
rock cycle
hydrologic cycle (the water cycle)
describe the tectonic cycle
involves the creation, movement, and destruction of tectonic plates
crust is broken up into 14 plates and they are moving around
7 big plates have the continents on them and there are 7 small plates that wedge in between
new land is formed at mid-ocean ridges and land is destroyed at subduction zones
—- plates separate and new lands come up
—- land is destroyed, sinking into the mantle in some areas to make room for new land
process is driven by Earth’s internal energy
what are tectonic plates? how many are plates are there? describe these plates
large blocks of the earth crust that form its outer shell
there are 14
7 big ones have the continents on them and there are 7 that wedge in between
describe Earth’s internal structure
lithosphere
— a thin and brittle crust
— rides on top of the asthenosphere
asthenosphere
— upper mantle
— composed of hot magma with some flow
— can become volcanic eruption
the inner core is extremely hot and solid
describe the crust of the Earth
the crust forms the upper part of the lithosphere and is broken into fragments (plates)
there are 2 types of crust, oceanic and continental
what are the types of crust?
oceanic
— dense, thin
— averages 7km thick
— supports water
continental
— relatively buoyant, thick
— averages 30km
— less dense and supports mountains
what causes the plates to move?
convection currents in the mantle
crashing into another -> sink
bc it is more dense, oceanic plates tend to sink more often
the rock would melt as it approaches the core and this is how we get magma
what are the types of plate boundaries
divergent, convergent, transform
divergent
— plates are separating
— magma comes up and hardens to form new land
— the spreading seafloor causes ocean ridges to form
——– the Atlantic Ocean is getting wider by a few cm every year
convergent
— plates move closer to each other
transform
— plates slide horizontally past each other
— the zone along which the movement occurs is called a transform fault
what was the evidence for the Pangea, super continent?
current mountain ranges (e.g. ours and the Alps) and fossils
which country is becoming smaller due to plate movement?
due to converging – India
India is continuing to push into the Asia
mountains are becoming taller there as well
describe the types of collisions
oceanic + continental crust = subduction zones
—- dense oceanic plates sink and melt
—- how we get magma and later on lava
—- melted magma rises to form mountains and volcanos aka Andes on the south American coast
continental + continental crust = collision boundaries
—- neither plates “sink” so they both push up
—- tall mountains tend to form aka Himalayas
—- process is very lengthy
the zone along which plates slide horizontally past one another is called what?
transform faults
what are hotspots? where are they found?
spots where magma rises from the mantle
the current is strong enough to push the magma from the crust, magma erupting at the surface results in the formation of volcanoes
—- hawaiian islands have hotspots underneath them and are at risk of volcanism
they’re found away from plate boundaries
describe the rock cycle
a group of interrelated processes that produce the 3 different rock types: igneous, sedimentary, metamorphic
what is a rock? importance of rocks?
an aggregate of one or more minerals
the type of rock in an area gives clues to geological events of the past
what are the 3 different rock types?
igneous
— rock used to be molting and magma which is now hardened
sedimentary
— most in Ontario
— from erosion and wind, making sediments
metamorphic
— apply pressure. it becomes metamorphic and we begin again
describe the hydrologic cycle
movement and exchange of water among the land, atmosphere, and oceans by changes in state
aka water cycle
solar energy drives the movement of water among the atmosphere, oceans, and continents
rain drops can stay in ocean for thousands of years but for a few days in the atmosphere
what benefits do we get from understanding hazards?
allows for identification of where hazards may occur
knowledge of past events aids in predicting future events – history repeats itself
many hazards are natural processes, they only become hazardous when they disrupt humans or the environment
— these processes are not within our control, we can’t prevent them, we can only respond
— the best solution to mitigate lost is prepare
how can we mitigate lost in regards to hazards?
accurate predictions and forecasts are necessary in order to reduce loss
some hazards can be predicted, many can be forecasted
—- hurricanes can be predicted, but we cannot predict an earthquake
what is a prediction?
a specific time, date, location, and magnitude of the event
what is forecast?
a range of probability for the event, not the same as prediction
how do we evaluate risk? (formula)
risk = probability of event x consequences
consequences = damage to people, property, the environment, or the economy
what is acceptable risk?
amount of risk that an individual is willing to take
the frequency of an event plays a role in determining the acceptable risk
a person does not ride a motorcycle, knows someone that was in a crash —- how personality plays a role in our decisions
give examples of how hazards are linked to each other or how does the environment play a factor in hazards?
earthquakes may cause tsunamis and landslides
hurricanes may cause tornadoes and flooding
some rock types are more prone to landslides
describe how population and population growth increase the risk of hazards
concentration of the human population creates greater loss of life in a disaster
it also puts greater demand on Earth’s resources
many people live in areas that are prone to hazards
describe the socioeconomic factor of hazards
economic losses from disasters are much higher in developed countries
deaths from disasters are much higher in developing countries
what are the direct and indirect effects of hazards
direct effects
—- deaths, injuries, displacement of people, property damage (what the media reports)
indirect effects
—- crops failures, starvation, emotional distress (PTSD), loss of employment
how can we deal with consequences of hazards?
we mainly deal with effects in reactive ways. but a higher-level strategy requires a proactive approach
reactive approach
— recovery, search and rescue, emergency food, water, shelter, and rebuilding
— we need the event to happen for this approach
proactive approach
— land use planning, building codes, insurance, evacuation planning, drills, structural control
what are the benefits of hazardous events?
some natural events provide important benefits aka “natural service functions”
e.g. flooding provides nutrients for soil – why flood plains are good for agriculture
landslides form natural dams that create lakes – how lakes are formed in mountainous areas
volcanic eruptions create new land – how new islands exist
which mountain chain is the result of an ocean-continent subduction zone?
Andes on the south American coast
