Eosc 114 Intro & Earthquakes

Front 1

Definition of a Disaster [3 parts!]

Back 1

Substantial event causing:

1) physical damage,

2) injury or loss of life, and/or

3) a drastic change to the environment

Front 2

Definition of Atomic Number

Back 2

The number of protons.

Front 3

Most common elements in the Earth's Crust [1st - 3rd]

Back 3

1st. Oxygen

2nd. Silicon

3rd. Aluminium

Front 4

Most common elements in the Ocean [1st - 3rd]

Back 4

1st. Oxygen

2nd. Hydrogen

3rd. Chlorine

Front 5

Most common elements in the Atmosphere [1st - 3rd]

Back 5

1st. Nitrogen

2nd. Oxygen

3rd. Argon

Front 6

Most common elements in the Earth's Core [1st - 3rd]

Back 6

1st. Iron

2nd. Nickel

3rd. Oxygen [?]

Front 7

Metric Prefixes: M, mega

Back 7

1x10^6

Front 8

Metric Prefixes: G, giga

Back 8

1x10^9

Front 9

Metric Prefixes: T, tera

Back 9

1x10^12

Front 10

Metric Prefixes: μ, micro

Back 10

1x10^-6

Front 11

Metric Prefixes: n, nano

Back 11

1x10^-9

Front 12

Metric Prefixes: p, pico

Back 12

1x10^-12

Front 13

Density definition - and how do you calculate it?

Back 13

How much Matter is in a Space [mass / volume = ρ]

Front 14

Compressibility Definition, and what factor does compressing change?

Back 14

Ability to be squeezed or expanded, so that the mass fills less or more space.

Results in a change in density [mass / volume] of the object, because the volume changes while the mass stays the same.

Front 15

How does density create Stratification?

Back 15

Less-dense materials float on top of denser materials. Creates layers or Stratification

Front 16

Viscosity Definition [what is something like w/ high viscosity?] - and what two factors affect viscosity?

Back 16

How thick a fluid is– Measure of resistance to flow. [High viscosity – thick, slow flow]

Depends on temperature & chemical structure.

Front 17

How does Gravity affect Force?

Back 17

Objects of mass (m) near the earth’s surface are pulled with force: [F = m · g]

Front 18

Force Definition - and what is its unit of measurement?

Back 18

A force pushes or pulls.

Its unit is the Newton (N).

Front 19

Work Definition

Back 19

The force (F) that pushes an object, times the distance (d) the object moves.

Front 20

Potential Energy (PE) Definition

Back 20

The work needed to raise an object of mass (m) a distance (z) against the pull of gravity (g) (e.g. a boulder on a cliff edge has a lot of potential energy)

Front 21

Kinetic Energy (KE) Definition

Back 21

A moving object possesses kinetic energy [KE = 0.5· m· v^2]

Potential energy can transform into Kinetic energy?

Front 22

Sensible Heat Definition

Back 22

Heat energy we can sense or feel –When we measure Temperature we are measuring sensible heat

Front 23

Latent Heat definition

Back 23

A kind of potential energy, consisting of “Hidden” heat energy in chemical bonds between atoms

Front 24

How is Sensible Heat affected during melting or boiling?

Back 24

Sensible heat “stored” as latent heat - heat is taken from the surroundings

Front 25

How is Latent Heat affected during condensing or freezing?

Back 25

Latent heat released as sensible heat - heat is transferred/released to the surroundings

Front 26

What scales are used when charting Order-of-Magnitude?

Back 26

Logarithmic Scale, which increases by powers of 10.

Front 27

What are the Earth's three main external energy sources? [e.g. not internally caused by decaying radioactive elements]

Back 27

1. Solar Irradiation [Largest]

2. Tidal Energy

3. Low Impact Energy (from meteorites etc.)

Front 28

Describe the Rock Cycle

Back 28

Heat and pressure (metamorphism) transforms sedimentary rocks into metamorphic rocks

Front 29

Risk definiton, and what is one way of writing it as a formula?

Back 29

Probability that any given hazardous event might occur, causing potential loss.

Can be written as: Hazard x Vulnerability = Risk

Front 30

Return Period (RP) Definition

Back 30

Average number of years between disaster events of the same magnitude (M)

Front 31

Carrying Capacity Definition

Back 31

The population that can be sustainably supported within a given domain (e.g., Earth)

Front 32

How has human population growth changed in recent years?

Back 32

Growth used to be exponential (1.1%/yr), but is now linear (1 billion more people every 13 years)

Front 33

What is the difference between the crust and the mantle, and which consists of the Earth's Tectonic plate?

Back 33

Crust is the top cold part, whereas the Mantle is the middle warm part. Tectonic plates [the Lithosphere] are made of SOLID crust and SOLID upper part of mantle.

Front 34

Lithosphere Definition

Back 34

The solid, brittle outer rigid shell of the Earth that lies above the asthenosphere [crust & uppermost mantle]

Front 35

Asthenosphere Definition

Back 35

The solid, ductile layer of the Earth below the Lithosphere where rocks deform readily and flow slowly. [mantle]

Front 36

3 factors that control Plate Tectonics

Back 36

1. Composition

2. Heat

3. Gravity

Front 37

3 types of Deformation

Back 37

1. Elastic - springs back (reversible)

2. Ductile - plastic flow (permanent)

3. Brittle - breaks (permanent)

Front 38

Factors that affect Deformation

Back 38

Temperature, pressure, and the speed/duration of deformation

Front 39

Differences between Continental and Oceanic Crust

[what they are made of, thickness, and density]

Back 39

Continental Crust is made of Granite, is thick and relatively less dense, Oceanic crust is made of Basalt, is thin and more dense

Front 40

Basal Drag definition [Plate Tectonics]

Back 40

Friction between the rigid Lithosphere and the more ductile asthenosphere drags the plate along

Front 41

Slab Pull definition [Plate Tectonics]

Back 41

Cold descending plate is denser than hot mantle, gravity pulls it down.

Front 42

Ridge Pull definition [Plate Tectonics]

Back 42

Heating at the rift raises the ridge crest, gravity pulls the elevated plates down and apart.

Front 43

What are the typical rates of convergence?

Back 43

Rates of convergence are approximately two to eight centimetres per year

Front 44

What are the three major plate boundaries?

Back 44

1. Convergent

2. Divergent

3. Transform

Front 45

What is the Earthquake fault and what forces are occurring in a Convergent plate boundary?

Back 45

It is a Thrust/Reverse fault, with strong Compression forces [plates moving towards each other]

Front 46

What is the Earthquake fault and what forces are occurring in a Divergent plate boundary?

Back 46

It is a Normal fault, with weak Tension forces [plates moving away from each other]

Front 47

What is the Earthquake fault and what forces are occurring in a Transform plate boundary?

Back 47

It is a Strike-Slip fault, with mid-strength Shear forces [plates moving against each other]

Front 48

Do all earthquakes occur in the Lithosphere or the Asthenosphere, and why?

Back 48

The Lithosphere, the Asthenosphere is too ductile.

Front 49

What are the 2 sub-types of Divergent plate boundaries, and what is formed in both of them?

Back 49

Oceanic <---> Oceanic plate spreading

Continental <---> Continental plate spreading

New Oceanic lithosphere is created

Front 50

Why is it always the oceanic plate that is subducted?

Back 50

Continental crust is much less dense (‘lower density’ - more buoyant) than mantle rock

Front 51

If two oceanic plates converge (convergent plate boundary), which one subjects and why?

Back 51

The older plate subjects, as it has had more time to cool, and is therefore more dense

Front 52

What are the three Earthquake locations in subduction zones at convergent plate boundaries?

Back 52

1) On the plate Interface [where Megathrust quakes are formed]

2) In the overriding plate

3) Within the down-going Lithosphere plate

Front 53

Elastic Rebound definition

Back 53

As rocks on opposite sides of a convergent fault are subjected to force and shift, they gradually uplift and compress until their elastic limit is exceeded. At that time, the brittle crust breaks at the hypocentre, causing very rapid subsidence and extension, and the rocks snap back to their original undeformed shape.

Front 54

What are the two sub-types of convergent plate boundaries, and which has the greater earthquakes?

Back 54

A). Subduction

Oceanic --\ <--- Oceanic plates

Continental plates ---> /-- Oceanic

B). Collision [V. large earthquakes]

Continental ---><--- Continental Plates

Front 55

If two continental plates converge (convergent plate boundary), which one subjects and why?

Back 55

Neither, as they fuse together [Collision], creating major deformation

Front 56

Is any lithosphere created or destroyed at Transform plate boundaries?

Back 56

There's no creation or destruction of lithosphere

Front 57

Which plate boundary has the most frequent earthquakes?

Back 57

Divergent (but they are generally weaker earthquakes)

Front 58

Difference between Hypocentre and Epicentre

Back 58

Epicentre is the ground-level point above the earthquakes actual point of origin, the Hypocentre

Front 59

How fast are P-waves, how do the particles move, what do the waves travel through, and how destructive are they?

Back 59

They are the fastest waves, the particles move back and forth with the direction of the wave [compressional], and the waves can travel through solid or fluid. The waves are not very destructive.

Front 60

How fast are S-waves, how do the particles move, what do the waves travel through and how destructive are they?

Back 60

They are the second fastest waves (behind P-waves), the particles bend perpendicular to the wave motion [transverse], and the waves can only travel through solids. Near-horizontal ground motion is very destructive.

Front 61

How fast are Rayleigh waves, how do the particles move, what do the waves travel through and how destructive are they?

Back 61

They are Surface waves, which makes them move relatively slowly, the particles move in a vertical circular motion. These rolling motions are the most destructive.

Front 62

How fast are Love waves, how do the particles move, what do the waves travel through and how destructive are they?

Back 62

They are Surface waves, which makes them move relatively slowly, the particles move side-to-side perpendicular to the wave. Surface waves are generally very destructive.

Front 63

Define Earthquake Magnitude

Back 63

Quantitative measure of the amount of shaking or ground motion (also area affected, duration) - related to the amount of energy released.

Front 64

Why can't S-waves propagate through fluids but P-waves can?

Back 64

Transverse waves (such as S-waves) need a medium rigid enough to propagate, and liquids do not have a high shear strength to allow the wave to pass through.

Compressional waves (Such as P-waves) do not require a high shear strength.

Front 65

What does the Local Richter Magnitude (Ml) measure?

Back 65

Maximum ground motion (surface wave amplitude)

Front 66

What two things do Body Wave (Mb) and Surface Wave (Ms) Scales measure - and what is one problem?

Back 66

These scales measure amplitude [Frequency and Ground Motion] - They are not accurate for large or distant earthquakes, as the larger the earthquake is, the more energy it generates at very low frequencies.

Front 67

What scale do Geologists now use to measure earthquakes?

Back 67

The Moment Magnitude scale

Front 68

What does the Moment Magnitude Scale measure, and what 3 physical properties does it look at?

Back 68

Measures strain energy along rupture surface (energy released) based on:

1). area of the fault

2). distance that the fault slipped

3). rigidity or stiffness of the rock (shear strength)

Front 69

In the Moment Magnitude Scale, the amount of Ground Motion increases logarithmically (by powers of 10), but how much does the amount of energy released increase for each factor of 10 increase in Magnitude?

Back 69

Increases by 10^1.5 (approx. 32 times)

Front 70

Can the Moment Magnitude Scale have Magnitudes that are negative, and can it have Magnitudes that go above 10?

Back 70

Magnitudes can be negative (v.small earthquakes), but a M10 quake is larger than is possible on Earth

Front 71

Earthquake Intensity definition - and what do we use to measure it?

Back 71

A qualitative estimate of how ground motion affects population and structures. How the shaking is perceived, combined with the damage resulting from vibrations [Descriptive, not Quantitative]

We use the Modified Mercali Scale to measure earthquake intensity

Front 72

Are buildings most damaged by horizontal or vertical shaking?

Back 72

Horizontal shaking

Front 73

What Ground Properties can increase our perception of earthquake intensity, and why?

Back 73

Water saturated sediment, because the soft ground 'filters' earthquake frequencies, affects how long the shaking continues, causes larger amplitudes and slower vibrations, and influences the stability of structure's foundations

Front 74

What [2] descriptions of buildings make them best suited to surviving earthquakes, and what [3] materials should be used when building them?

Back 74

Flexible and Strong, and preferably made of Wood, steel, and/or reinforced concrete

If the building is tall, then it can be tuned to avoid resonance disasters

Front 75

Resonance Disasters definition

Back 75

When 'forcing' earthquake vibrations are tuned to one of the primary resonant frequencies of a structure, it can cause dramatic shaking

Front 76

Do taller or shorter buildings have lower natural resonant frequencies?

Back 76

Taller Buildings

Front 77

Liquefaction definition

Back 77

Shaking causes soft, wet, unconsolidated soils to 'liquify' (contact forces decreasing between the soil grains) - loosening its cohesion and causing it to flow

Front 78

What is the name of the area parallel to the Convergent plate boundary of the Juan De Fuca plate, where the hypocentre of a Megathrust earthquake can occur?

Back 78

Megathrust locked zone

Front 79

What evidence would you look for to see when previous Megathrust earthquakes had occurred on a convergent boundary?

Back 79

Elastic Bending and Compression (gradual uplift of the plate and shortening --><--), can also look for evidence of past tsunamis (e.g. thick sand layers) and turbidites (underwater landslides). Also written/oral history

Front 80

Return periods for M9 and M8.3 earthquakes in the Cascadian region.

Back 80

M9: roughly 500 years

M8.3 roughly 230 years

Front 81

Which hypocentre location in a subduction zone would be the worst for Vancouver?

Back 81

A shallow crustal quake occurring on the plate Interface

Front 82

What are earthquake Precursors, and are they useful in predicting earthquakes?

Back 82

Anomalous observations that precede an earthquake - they are not useful as they are neither reliable nor repeatable.

Front 83

Seismic Gap definition

Back 83

A segment of an active fault known to produce significant earthquakes which has become locked - strain accumulates but no ruptures occur. Indicates a zone with increased large earthquake likelihood

Front 84

Geodynamic research into crust deformation and computer modelling may enhance what?

Back 84

Earthquake forecasting (< 10 years)

Front 85

How many seismograph stations do you need to locate an earthquake's hypocentre?

Back 85

three, that can triangulate the delay in arrival time between P and S waves

Front 86

How are Tsunamis created?

Back 86

The fault rupturing the seafloor and lifting/dropping the entire water column situated above the fault [NOT caused by the earthquake waves]

Front 87

Do Earthquakes often trigger volcanic activity nearby?

Back 87

No, only on very rare occasions.

Front 88

What are turbidites, and what generally causes them?

Back 88

Underwater landslides, caused by Megathrust earthquakes