Final Flashcards
Earthquakes are measured by ___________
seismographs
Earthquakes are compared by ___________
Magnitude
D: Seismic Waves
The energy released from an earthquake
Earthquakes are
The result from the rupture of rocks along a fault
Richter Scale
The original way to measure the magnitude of an Earthquake (no longer)
Earthquakes are measured using
The Moment Magnitude Scale (M)
The Moment Magnitude Scale is determined by:
- the area ruptured along a fault
- the amount of movement along the fault
- the elasticity of the crust at the focus
An M7 earthquake has how much more ground movement than an M6
10 times as much
What is the Modified Mercalli Intensity Scale
It is a qualitative scale for Earthquakes that is based on damage to structures and the effect on people
Where are Earthquakes most common
At or near plate boundaries
Blind faults are
located below the surface
What are faults considered
Seismic sources
What are the 2 types of geologic faults
Strike-slip faults and Dip-slip faults
Strike-slip faults
Displacements are horizontal
Dip-slip faults
Displacements are vertical
What are the three types of Dip-Slip Faults
Reverse Faults, Thrust Faults, Normal Faults
Dip-Slip faults are comprised of what 2 walls
Footwall, (where miners placed their feet)
and
Hanging-wall (where miners placed their lanterns)
Reverse Fault
Hanging wall has moved up relative to the footwall inclined at an angle steeper than 45 degrees
Thrust Fault
Hanging wall has moved up relative to the footwall at an angle less than 45 degrees
Normal Fault
The hanging wall has moved down relative to the footwall
What are the 3 categories of faults
Active, Potentially Active, Inactive
Active Fault
Movement during the past 11,600 years
Potentially Active Fault
Movement during the past 2.6 million years
Inactive Fault
No movements in the past 2.6 million years
Tectonic creep
The slow movement of rock or sediments along a fracture caused by stress
P Waves
Primary (or compressed) waves move fast with a push-pull motion and can travel through solids or liquids
S Waves
Secondary (or shear) waves move more slowly in an up-and-down motion and can only travel through solids
What are the 2 types of Body waves
P waves and S waves
Surface Waves
Seismic waves that form when P and S waves reach Earth’s surface and then move along it
What are responsible for damage near the epicenter of an earthquake
Surface Waves
What are some factors that determine the shaking people experience during an earthquake
- magnitude
- distance to epicenter
- Focal depth (how deep is earthquake?)
- direction of rupture (how was fault aligned?)
- local soil and rock types
local engineering and construction practices
Which type of wave travels faster: P wave or S waves
P waves travel faster and appear first on seismograms
How can we find the distance to the epicenter in an earthquake
Using the difference in the arrival times of the first P and S waves at different locations
What can influence the amount of ground motion
local geology
Where are Earthquakes felt over larger areas
Earthquakes in eastern North America are felt over larger areas than those in western North America
(less rock types and big mountains)
foreshocks
A small to moderate earthquake that occurs shortly before and in the same general area as the mainshock
Mainshock
The largest earthquake in a series of associated earthquakes
Aftershock
A small to moderate earthquake that occurs shortly after and in the same general area as the mainshock
Describe the earthquake cycle
- Inactive period
- Period where strains produce minor earthquakes
- period of foreshocks (not always)
- period of mainshock allowing fault to release built up stress
- Period of aftershocks
What is the formula to calculate how many aftershock there should be after an earthquake
aftershock on given day = (# of aftershocks on the first day after / the given day)
If there were 200 aftershock the next day after an earthquake, how many should you expect on day 7
= 200/7
= 29
Where do most earthquakes occur:
Along plate boundaries:
Pacific Ring of Fire, Himalaya Mountains, Middle East
What are some NA cities that are at high risk for earthquakes
Anchorage, Vancouver, Victoria, Seattle, Portland, San Francisco, Los Angeles, Mexico City
Plate boundary earthquakes
Earthquakes that occur on faults separating lithospheric plates
The 3 types of plate boundary earthquakes
strike-slip earthquakes
thrust earthquakes
normal fault earthquakes
Strike-slip Earthquakes
Occur along transform faults where plates slide horizontally past one another (common in California)
Thrust Earthquake
Occur on faults that separate converging plates (also called subduction earthquakes)
The strongest types; can produce tsunamis (common in BC)
Normal fault earthquakes
Occur on faults associated with divergent plate boundaries
(common along Mid-Atlantic Ridge)
Intraplate Earthquakes
An earthquake on a fault in the interior of a continent, far from a plate boundary
(typically smaller than plate boundary earthquakes)
Primary effects of earthquakes
Ground shaking, surface ruptures
Secondary effects of earthquakes
liquefaction, land-level change, landslides, fire, tsunamis
Liquefaction
The transformation of water-saturated sediment from solid to liquid
Natural service functions of earthquakes
- Faults provide pathways for the downward flow of surface water
- Can channel groundwater to surface discharge points (springs)
- New material resources can be found
- Scenic landscapes can develop in fault zones over time
What is the main reason earthquakes cause such death and destruction
They occur with little to no warning
What are the safest location during an earthquake
Under desks and tables
Where are most volcanoes located
Near plate boundaries
2/3 of volcanoes are found where
On the “Ring of Fire” surrounding the Pacific ocean
Magma
Found within the crust and upper mantle
Lava
found flowing from an erupting volcano
what is the relationship between lava and magma
lava is essentially magma on the earths surface
What are the most abundant elements in magma
Silicon and oxygen
What are the types of volcanic rocks from least silica present to most
Basalt
Andesite
Dacite
Rhyolite
What else is contained in magma
small amounts of gases (water vapour, CO2)
Describe Magma with high silica content
Cooler, more viscous, more gases
Describe Magma with low silica content
Hotter less viscous, fewer gases
What influences a more explosive volcanic eruption
Volcanoes with higher silica magma
Which 2 types of magma produce volcanoes that tend to flow
Basalt
Andesite
Which 2 types of magma produce volcanoes that tend to explode
Dacite
Rhyolite
What are volcanoes classified based upon
Shape
Appearance
Style of eruption
What are the 4 types of volcanoes
Shield
Composite
Volcanic Dome
Cinder Cone
Shield Volcanoes
Largest volcanoes on earth
Shaped as broad arcs
Associated with Basaltic Magma
Flows
Common in Hawaii, Iceland
Tephra
Fragmented material blown out during an eruption
Compacted together are referred to as pyroclastic rock
Composite Volcanoes
More dangerous and explosive eruptions
Less common than shield
Common along the west coast from Alaska to Northern California
Volcanic Domes
Steep-sided mounts that form around vents
Contain highly viscous rhyolite magma
Cinder Cone Volcanoes
Relatively small volcanoes composed of small pieces of tephra
Found in Mexico
Ice-Contact Volcanoes
Erupt beneath or against Glaciers
When the lava contacts glaciers it quickly cools to form pyroclastic rock
Found in Iceland and BC
Geyser
Groundwater that boils underwater and periodically produces a release of steam or water
here are Geysers most common
About half of all geysers on earth reside in Yellowstone
About how many volcanoes erupt each year
50-60 volcanoes
What is an effect volcanoes have
Powerful eruptions can impact global climate
Lava flows
occur when magma flows out of a central crater
Pahoehoe Lava
Low viscosity (a few km per hour), high temperature. When hardened, it has a smooth texture
Aa Lava
High viscosity (a few meters per day), lower temperature. When hardened, it has a blocky texture
Lateral Blasts
An eruption directed away from a volcano where materials are blown parallel to the surface
Ash Fall hazards
- destroys vegetation
- contaminates surface water
- health hazards to people and animals
- causes aircraft engine failure
Pyroclastic flows
Avalanches of ash, gas, and rock that travel down the slopes of a volcano during an explosive eruption
Largest cause of death involving volcanoes
Natural Service functions of volcanoes
- Internal heat from volcanoes can produce renewable geothermal energy
- Volcanic soils can be good for agriculture
- Volcanic landscapes attract tourism and recreation
Eruptions can create new land (Hawaii, Iceland)
What are ways to minimize the volcanic hazard
1 Monitor seismic activity ((shallow earthquakes usually precede)
2. Thermal and Hydrologic monitoring
3. Land surface monitoring
4. Monitoring volcanic gas emissions
5. Understanding local geologic history
What are technological hazrads
They have a wide and varied interpretation
Can vary from a single toxic chemical accident to an entire industry (e.g. nuclear energy)
T/F: Death tolls from technological hazards are relatively high
False
T/F The people at the greatest risk involving technological hazards are those involved in the industry
True
hat are the 3 categories of technological hazards
Widespread
Rare events
Relatively common
What are some examples of Widespread technological hazards
Nuclear accidents
Hazards leading to cumulative effects
What are some examples of Rare event technological hazards
Airplane crashes
Mine collapses
Shipwrecks
What are some examples of relatively common technological hazards
Car accidents
Poisons
Cumulative effects
Conditions that worsen slowly over time as exposure to a concentration increases
(Ex. exposure to toxic chemicals, acid)
The second leading cause of lung cancer in North America
Radon
Why is Radon difficult to detect
It is colorless, odorless, and tasteless
T/F: Radon can move quickly through non-saturated soil and can seep into homes
True
Genetically Modified Organisms (GMOs)
Organisms that have had changes made tot heir DNA by the transfer of genes
What are common crops that have been genetically modified
Corn
Soybean
Canola
Whay are crops genetically modified
To increase yields
What do genetically modified crops have greater resistances to
- Changes to temperature and precipitation
- Herbicides
- Pests
- Acidic soil
What are the main sources of radiation
- Mining Uranium (Mines produce wastes that can be a radioactive hazard)
- Production of Electricity (Uranium is used in nuclear power plants)
hy are most nuclear plants in NA in the Eastern half of the continent
They must be near sources of coolant (rivers or lakes)
Nuclear Meltdown
Occurs when the heat generated by a nuclear plant exceeds the heat removed by cooling systems
What happened during the Chernobyl Nuclear Accident
It was the worst nuclear disaster in world history which occurred on April 26, 1986
Accident resulting due to flawed design
Why do we push for nuclear plants
The concern for greenhouse gas emissions outweigh our concern for possible nuclear disasters
T/F: Oil spills are relatively quick to clean up
False. clean-up can take months to years
Groundwater
Water that is found underground within the cracks and spaces in soil, sand, and rock
How was the solar system formed
Scientists believe a cloud of gas and dust in space was disturbed by a supernova (4.6 billion years ago)
The explosion made waves in space causing the formation of a solar nebula (flattened cloud of gas and dust)
Solar nebula grew hotter and became the sun; outer edges cooled causing clumps to stick together and form planets
Galaxy
A cluster of billions of stars. Our solar system makes up a tiny portion of the Milky Way Galaxy
Star
A hot glowing ball of gas that generated energy by converting hydrogen to helium
How hot is the core of the sun
15,000,000 deg C
he solar system is composed of:
8 planets
60 moons
millions of bolides
What is the order of planets
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Bolides
Extraterrestrial bodies that originate in outer space
Asteroid
A rocky metallic material in space 10m to 1000km in diameter originating in the asteroid belt
Where is the asteroid belt
between Mars and Jupiter
Meteoroid
Smaller objects in space up to 10m in diameter
Meteor
A meteoroid that has entered Earths atmosphere
Meteorite
A meteor that strikes the earths surface
Comet
Composed of a rocky core of glass and ice
these are distinguishable by a glowing tail of gas and dust.
What provides us with evidence of past meteorite impacts
Impact Craters
How many major extinctions have there been
5 in pat 550 million years
What is the K-T Boundary Mass Extinction
An event 65 million years ago that caused the extinction of the dinosaurs (70% of all plant and animal spiecies at the time)
Bolide impacts can cause what other hazards
tsunamis
earthquakes
landslides
climate change
T/F: We are able to detect approaching large bolides decades in advance
True
T/F: The best course of action dealing with an approaching bolide is to blow it up
False. It is best to push it off course
Snow Avalanche
A mass of snow many cubic meters in volume that separates from a snowpack and flows downslope
T/F: For snow to accumulate the mountain slopes must be at angles less than 75 degrees
False. Accumulates at angles less than 60 degrees
What are the 2 types of Avalanches
Point-release Avalanche
Slab Avalanche
Point-Release Avalanches
Begin as initial failure after a heavy snowfall
The sliding snow then causes more failures in the adjacent snowpack
Slab Avalanches
Occur when a snowpack fractures along a weak layer parallel to the surface
These avalanches move as cohesive blocks leaving behind a scarp
*Most dangerous
What is the danger zone for slopes
30-45 deg
How does new snow impact avalanche potential
New snow that hasn’t been able to bond to the layer below is susceptible to sliding
What are the 2 ways weak layers can be formed
From wind or from hoar
How does wind create a weak layer
Blowing snow can accumulate on the lee slope of mountains
T/F: An avalanche cannot go upslope
False. Some avalanches are powerful enough to climb opposing slopes
Avalanche start zone
The area where the snowpack first fails
Avalanche Track
The area along which the avalanche accelerates and reaches maximum velocity
Avalanche Run-out zone
The area of deceleration and snow deposition
At what angles of slope do most avalanches occur
Most occur at angles between 25-60 deg
<25 snow does not easily slide down
> 60 little snow accumulates at the top
T/F: Many a times avalanches are caused by people
True.
What other natural disaster can cause an avalanche
Earthquake
What are some natural service functions of Avalanches
- May increase local plant and animal diversity
- Maintain open area in otherwise forested regions
- Can serve as an important habitat zone for certain plants and animals
How do we minimize avalanche risk
- keep infrastructure outside the dangerous areas (using hazard maps)
- specially build any infrastructure built in danger zone
- Use deflection structures or splitting wedges
- Controlled triggers to force avalanches to prevent snowpack buildup
What are the 3 Strength and Stability tests to assess a snowpack
Compression Test
Shovel Test
Rutschblock Test
Compression Test
A vertical force is placed on top of the snowpack to detect weak layers
Shovel Test
It assesses the strength by isolating a column of snow and applying force on the uphill side
Rutschblock Test
A skier pushes and jumps on a column of snow to detect cohesion of the snowpack
(best assessment)
What are some Avalanche survival aids
Avalanche Cord
Avalanche Transceiver
Avalanche Dogs
What 2 things naturally start many fires
Lightning and volcanic eruptions
What 3 elements does a wildfire require
Fuel, Oxygen, and Heat
What are the 3 phases of a wildfire
pre-ignition, combustion, extinction
Pre-ignition phase
As vegetation is heated (to a temp it can ignite), it often loses water
Combustion phase
Begins with ignition
Can be Flaming combustion or smoldering
Flaming Combustion
Rapid, high temperature conversion of fuel into heat
Smoldering combustion
Occurs in areas with burned material and ash that covers new fuel.
What are the 3 processes that control the transfer of heat as a wildfire moves across land
Conduction - Transfer of heat by molecule to molecule contact
Radiation - Transfer of heat in the form of invisible waves
Convection - Transfer of heat by movement of a liquid or a gas
Extinction phase
Combustion has ceased; no longer sufficient heat or fuel to sustain a fire
What are some types of fuel for a wildfire
leaves, woody debris, decaying organic material, grasses, shrubs, etc.
Which regions are most at risk for wildfires
In Canada the greatest risks are in BC and in the boreal forests of the Canadian shield
What are the 2 types of fires
Surface fires and Crown fires
Surface fires
Travel close to the ground and burn shrub, leaves, twigs, grass, etc.
Crown fires
Move rapidly through the forest
Can be fed by surface fires that move up limbs or tree trunks
They are driven by strong winds and common in boreal forests
What are some Natural Service Functions of Wildfires
- Reduces competition for sunlight and moisture in a forest
- For some species it triggers the release of seeds
- Can remove some parasites and micro-organisms in the soil
- Removes diseased trees
Pioneer Vegetation:
The first plant species to appear after a wildfire
Fire regime:
The potential for wildfire in an area
What does fire management entail
Objective is to control wildfires for the benefit of the ecosystem (letting it burn), while also preventing them from harming people and destroying property
Fire Break
An area with no fuel (ex. rivers, lakes, roads)
Describe a fire suppression strategy
A strategy is to steer the fire toward a fire break
If one doesn’t exist to create one then do it
Prescribed burns
These are controlled fires that are purposely ignited to reduce the amount of fuel
In which type of fault does the hanging wall move up relative to the footwall at a relatively steep angle?
Reverse Fault
P and S waves are which type of waves
Body Waves
What is the term for the largest earthquake in a series of associated earthquakes
Mainshock
Assume a major earthquake occurred and on the day after 75 aftershocks were reported. How many aftershocks would be forecasted to occur 5 days after the major earthquake
=75/5
=15
Name a major city in the U.S that is at risk of expecting a strong intraplate earthquake
Memphis
St. Louis
Data from at least how many seismic stations are required to determine the location of an earthquake
3
Which type of wave moves in a snake-like motion
S wave
What is the term for the transformation of solid material to a liquid state
liquefaction
What is the term for the location where the rocks first rupture during an earthquake
focus
Which Scale is a qualitative scale to measure earthquakes
Modified Mercalli
What is the term for an increase in ground motion as body waves transfer to surface waves
Amplification
Amplification
An increase in ground motion during an earthquake
Alluvial
Soil that was deposited by water (very soft soil)
Which type of earthquakes are the strongest on Earth?
Thrust Earthquakes
Which type of material has been deposited by water
Alluvial
Where did the strongest Earthquake in Canada Occur
British Columbia
Which of these has the lowest Viscosity:
a) ketchup
b) water
c) milk
b) water
Which type of volcano is most common in Hawaii
Shield
Rank these Volcanoes in order of their last eruption from oldest to most recent:
- Mt. Pinatubo
- Yellowstone
- Mt. St. Helens
- Mt. Tambora
- Yellowstone
- Mt. Tambora
- Mt. St. Helens
- Mt. Pinatubo
Mt St. Helens is associated with which feature of plate tectonics?
Convergence Boundary
What is a general term for fragmented material that is ejected during an eruption
Tephra
What is the deadliest feature of volcanoes
Pyroclastic flow
What is another term for mudflow
Lahar
What is the term for a volcanic crater produced by an explosion from groundwater encountering magma?
Maar
Maars
A circular crater produced by an explosive eruption and filled with water
Mt St. Helens is which type of volcano
Composite
Which type of basaltic lava hardens with a blocky texture
Aa
What is an explosion directed horizontally out of the side of a volcano?
Lateral Blast
The eruption of which volcano resulted in the “year without a summer”?
Mt. Tambora
In North America, on which side of a slope is an avalanche most likely?
Southeast
Rank These slope angles in order which they would be most likely to experience an avalanche (from highest likelihood to lowest):
- 20 Degrees
- 35 Degrees
- 60 Degrees
- 35 Degrees
- 60 Degrees
- 20 Degrees
The direction that a slope faces is referred to as the ____________ of the slop
orientation
What is the name of the area on a slope where an avalanche decelerates, and snow deposition occurs?
Run-out zone
What is the name of the structure that allows snow to pass over highways and railroads without disruption to traffic?
Avalanche Sheds
Which stability test involves pushing on the side of an isolated area of a snowpack?
Shovel Test
In North America, which side of a hill or a mountain would be least likely to experience a wildfire
Northeast
Which transfer of heat occurs through a liquid or gas
Convection
What is the name of a vertical rotating funnel-shaped swirl of fire?
firenado
Match: A large fire that occurs on a forest floor or grassland area
a) Crown Fire
b) Surface Fire
c) Spot Fire
b) Surface Fire
Match: The fast moving type of fire
a) Crown Fire
b) Surface Fire
c) Spot Fire
a) Crown Fire
Match: A small fire that is often triggered by embers
a) Crown Fire
b) Surface Fire
c) Spot Fire
c) Spot Fire
Leaves, twigs, and debris are examples of what?
Fuel
What is the term for potential for wildfire in an area
Fire regime
Which of the following is not on of the elements of fire
a) Heat
b) Oxygen
c) Radiation
c) Radiation
What is the term for the first plant life to appear in an area after a wildfire?
a) Pioneer Vegetation
b) Boreal Forest
c) Colonizing Plants
a) Pioneer Vegetation
What is the name of the phase of a wildfire that includes flaming
Combustion phase
What is the term for a purposely set controlled fire?
Prescribed burn
In which province is the mountain pine beetle most greatly impacting forests?
British Columbia
Firefighters try to steer a fire toward this, It is an area that lacks fuel
Fire break
Which physiological system would be least affected by smoke from wildfires
a) Ocular
b) Circulatory
c) Respiratory
b) Circulatory
