EOSC 114 Study Guide - Final Guide: Cascadia Subduction Zone, Juan De Fuca Plate, Queen Charlotte Fault

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Published on 14 Apr 2013
School
UBC
Department
Earth and Ocean Sciences
Course
EOSC 114
EOSC 114 Final Review Notes
Unit 1: A Fragile System
Explain what density is & how it relates to stratification.
o Density = mass/volume; how much mass fits into a space. Unit: kg/m3 3
o Stratification = less-dense materials float on top of denser materials
This is found in the atmosphere, the ocean, the earth, etc.
Explain why disaster scales are based on the Order-of-Magnitude concept, and interpret graphs with logarithmic
scales.
o Without using a log scale, sometimes a graph will be too large.
o “Orders of magnitude” are powers of 10 – a logarithmic graph steps by powers of 10
Converting an exponential curve into a logarithmic graph will give a linear graph.
o Many disaster scales use powers of 10: Richter, Fujita, Torino, Beaufort, etc.
Relate natural-disaster risk & intensity to frequency, return period, and consequences (costs).
o Risk = probability severity * cost of damage ($ + human lives)
o Intensity is inversely proportional to frequency.
o Return period = average number of years between disaster events of the same magnitude
RP (M) = time span of data / # of cases of magnitude M.
Explain how some recent disasters were associated with concentration or dilution of energy.
o Time scales for energy to build up and release
Concentration of energy
Dilution of energy
Earthquakes: years -> minutes
Volcanoes: decades -> days
Hurricanes: months -> days
Storms: hours -> minutes
Rogue waves: hours -> seconds
Tsunami: minutes -> hours
Floods: hours -> days
Get the disaster info you need from reliable sources.
Compare tectonic, rock, hydrologic, and biogeochemical cycles.
Tectonic Cycle
o Involves the creation -> movement -> destruction of plates
o One cycle can last more than 200 million years!
o Types of plate boundaries
Divergent: two plates move away
Forms: large, underwater mid-ocean ridges
Rifts formed through seafloor spreading
Convergent: two plates collide
Subduction zone: one plate moves beneath another (usually ocean and continental)
At 100-120 km, melts and releases H2O and CO2 -> hot enough to cause lower crust to
melt -> magma moves up -> reaches surface -> erupts
Transform boundary
Movement along a transform fault most are beneath oceans but some are on continents
Rock Cycle
o Rock: aggregate of one or more minerals. Mineral: naturally occurring crystalline substance w/ specific
elemental composition
o Rock Cycle: recycling of three major groups of rock
Crystallization of molten rock -> igneous rock beneath/on Earth’s Surface
Weathering -> sediment
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Sediment is transported by wind/water/ice to depositional sites
Buried -> lithification -> sedimentary rock
Chemically active fluids + heat + pressure cause metamorphic rock to be formed
Eventually, temp high enough -> melt -> restart
Water Cycle
o Cycling of water from oceans -> atmosphere -> continents -> back again
o Driven by solar energy
o Residence time: estimated avg time a drop of water spends in any part of the cycle
Only a tiny fraction of earth’s water is active at a certain time – often stored
Only ~.3% of all water important for life -> groundwater
Biogeochemical cycles
o Cycling of an element/elements through atmosphere/lithosphere/hydrosphere/biosphere
Related to the other cycles
Tectonic provides water + gas, heat + energy. Rock and hydrological transfer and store.
Elements and chemicals are transferred via storage compartments/reservoirs
When a biogeochem cycle is understood, the rate of transfer (flux) among all components is known
List the 1st and 2nd most common elements in the earth, ocean, and atmosphere.
Elements
Earth
Crust
Ocean
Atmosphere
1st most common
Fe
O
O
N
2nd most common
O
Si
H
O
3rd most common
Ni
Al
Cl
Ar
Describe how viscosity and compressibility relate to the phase of matter.
o Fluids: Easily flow, change shape easily = gases, liquids
o Viscosity: measure of how much fluids resist flowing or changing their shape.
Greater viscosity, more resistance. Depends on temperature + chemical structure.
o Compressibility: ability to be squeezed/expanded. Results in a change in density because of volume change.
o Phases of matter
Solids: Not fluid, not very compressible.
Liquids: Very fluid, not very compressible.
Gases: Very fluid, very compressible.
Be able to diagnose the type of strain by the way a material deforms.
o Strain: Change in shape or size of a solid object (deformation)
Elastic: Ability to change shape when forced but spring back to original shape when force lifted
Plastic: Ability to permanently change shape or deform when forced
o Ductile = very plastic, Brittle = not very plastic, fractures instead of bending.
Explain how gravity affects motion and energy, list the 5 types of energy, and describe what causes them to vary.
Force (F)
A push/pull
Unit: Newton = 1 (kg * m/s^2) -> F = ma
A 15 km/h breeze = 1 N
Gravity (g)
Force that attracts matter
G = 9.8 m/s2 = gravitational acceleration
Work (W)
Work = force x distance in = Joules
Potential Energy
Mass * gravity * height (distance against pull of gravity)
Kinetic Energy
0.5 m V2
Sensible Heat (QH)
Heat we can feel
ΔQH = m C ΔT
o C = specific heat capacity
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Latent Heat (QE)
When solids melt/liquids evaporate sensible heat becomes stored as latent heat
o When they condense/freeze - > released
QE = LΔm
Delta m = change in mass
Constants
o Latent Heat of Vaporization: liquid -> gas, Lv
o Latent heat of fusion: liquid -> solid, Lf
Explain the 5 main concepts for understanding natural processes as hazards.
1. Hazards can be predicted through scientific analysis
Scientific method used
Predicted by
Identifying location, finding probability, looking for precursor events, forecasting, warning
2. Risk analysis is an important element in understand the effects of hazards
Risk = probability * consequences
3. Linkages among different hazards exist
4. Damage from natural disasters is increasing
5.
6. Damage and loss of life can be minimized
Explain (with examples) how energy conservation applies to natural disasters.
o Energy is conserved when it changes form.
o Most sources of energy are diffuse: weak, but cover a wide area
o Disasters generally have a concentration of energy into a small area
Describe relationships between force, pressure, stress, strain, energy, and power.
Power: work/consuming energy per second = measured in watts
o Pressure: force per unit surface area applied perpendicular to a surface
o Stress: force per unit area applied parallel to a surface
Stress tends to strain deform objects
Describe population growth and explain why it is important for natural disasters.
o Population growth was exponential over the past 12,000 years
Doubling time = 70/growth rate
Applies only to an exponentially growing pop
o Carrying capacity + overpopulation limit the growth
Recent growth is linear -> growth limited?
o With greater population = infrastructure is more important + sensitive
Transport, communication, utilities etc
Harder to evacuate + communicate if damaged by disaster
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Document Summary

Explain what density is & how it relates to stratification: density = mass/volume; how much mass fits into a space. Unit: kg/m3 3: stratification = less-dense materials float on top of denser materials. This is found in the atmosphere, the ocean, the earth, etc. Explain why disaster scales are based on the order-of-magnitude concept, and interpret graphs with logarithmic scales: without using a log scale, sometimes a graph will be too large. Orders of magnitude are powers of 10 a logarithmic graph steps by powers of 10. Converting an exponential curve into a logarithmic graph will give a linear graph: many disaster scales use powers of 10: richter, fujita, torino, beaufort, etc. Rp (m) = time span of data / # of cases of magnitude m. Explain how some recent disasters were associated with concentration or dilution of energy: time scales for energy to build up and release. Get the disaster info you need from reliable sources.

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