EOSC 114: Earthquakes Learning Goals
EOSC 114: Earthquakes Learning Goals
1. Describe the global distribution of earthquakes and how often quakes of various magnitudes occur 2. Understand the different types of faulting at different plate boundaries, and which plate boundaries produce the largest quakes
3. Describe how the Earth builds, stores, and releases energy in earthquakes (elastic rebound)
4. Understand concepts of (1) stress causing strain and (2) plastic versus brittle deformation
5. Describe how the rupture propagates from the focus and why shaking and damage are not necessarily greatest at the epicenter 6. Describe the different types of seismic waves and how they move through the Earth
- globally, earthquakes located mostly on tectonic plate boundaries - higher frequency = lower magnitude; higher magnitude = lower frequency Plate boundaries+ Faults: 1. Divergent: Plates move apart at mid-ocean ridges & spreading centressmall earthquakes normal dip-slip faults 2. Transform: Plates slide beside each other (shearing) many medium-large earthquakes strike-slip faults 3. Convergent Type 1: Plates collide, causing compression. One plate is more dense and subducts under other small to largest earthquakes (at subduction zone) reverse dip-slip faults 4. Convergent Type 2: Plates collide, causing compression. Neither subducts so crumple, form mountains small to large earthquakes reverse dip-slip faults Constant movement of tectonic plates over many years builds pressure, storing PE. Increased stress breaking, so too much stress causes a slip, releasing energy in an elastic form (reverting to original form) 1. Stress is force/unit area, while strain is how material changes shape from stress. ie.strain is change in shape due to stress 2. Plastic deformation is permanent change, ie. hammering gold sheets. Brittle is breakage, does not hold plastic shape well, ie. hammering glass plate
1. Body Waves: travel in earth (faster than surface waves) in curved pathways (refracted due to earth layers) a) P-wave (primary) particles move back & forth in direction wave is travelling (ex. slinky) b) S-wave (secondary) particles move vertically perpendicular to direction wave is travelling (ex. up&down snake); can’t travel through liquids/water 2. Surface Waves: travel on surface of earth (slower, more damaging than body waves) a) Rayleigh Waveslargest, most damaging; particles rotate backwards, counter clockwise (like ocean)
EOSC 114: Earthquakes Learning Goals b) Love waves: particles move horizontally perpendicular to surface (slithering snake) 7. Understand the principle behind early warning systems (such as the one in Japan) and how much warning time they can give 8. Describe how an earthquake is recorded and how to locate the epicenter
9. Understand how local ground conditions can affect the duration and amplitude of shaking 10. Compare and contrast the meanings and uses of earthquake magnitude and intensity scales 11. Explain the different magnitude scales, which one is best for large quakes, and why
12. Explain factors that determine earthquake intensity
13. Be aware of how earthquakes can be the cause of other natural disasters (e.g., tsunamis, liquefaction, landslides) 14. Understand the basics of how buildings can be designed or retrofitted to better resist earthquakes (and reduce casualties)
-Mainly relative arrival times b/w P-waves and S-waves; larger time difference = farther away -Using distances from 3 recording stations, find the 1 overlapping spot – this is epicentre Type of ground greatly affects shaking intensity hard rocks don’t move as much, softer rocks will move more Magnitude: the strength of an earthquake, on its own Intensity: how much of the earthquake is felt; see 12 -Richter: not used as much now, best for Southern California & seismometer specific; increments of 32x - Moment Magnitude: best because calculates magnitude without estimating ground travel time; uses logarithmic scale, each increment represents 32x stronger magnitude - Note: shaking scale means increments are 10x stronger; magnitude scales are 32x stronger 1. Earthquake magnitude bigger magnitude = higher intensity, if close to people 2. Duration of Shaking longer shaking = higher potential for damage 3. Distance from epicenter/hypocenter usually, more intense the closer to epicenter 4. Ground Typevery important. Hard rocks don’t move as much, softer rocks will. 5. Building Characteristics buildings don’t usually withstand horizontal movement; when moving at building’s resonance frequency, will be more susceptible to damage, feel more intense Liquefaction: soils that are compact when dry will loosen with water and shaking, not strong enough to support buildings -Static Methods:add cross braces (X over window),shear walls (side brace along wall), and shear core (central columnar core) - Dynamic Methods: absorb shock (springs or dampers), change resonant frequency (add mass strategically), and allowing earth to move without building (using isolating foundation w/rubber blocks)
EOSC 114: Earthquakes Learning Goals 15. Identify fault zones that could produce an earthquake damaging to Vancouver 16. Explain what we can and cannot predict about large earthquakes 17. Know the difference between forecasting and prediction
18. Make informed decisions about earthquake safety - how to act, how to prepare
- Cascadia subduction zone fault; Juan de Fuca plate subducts under North American plate - Can predict it will happen within a certain period… but cannot predict exactly when Prediction: very specific…. not going to happen with earthquakes Forecasting: more accurate in short term, fuzzier in long term; like weather forecasting
1. Describe the global distribution of earthquakes and how often quakes of various magnitudes occur 2. Understand the different types of faulting at different plate boundaries, and which plate boundaries produce the largest quakes
3. Describe how the Earth builds, stores, and releases energy in earthquakes (elastic rebound)
4. Understand concepts of (1) stress causing strain and (2) plastic versus brittle deformation
5. Describe how the rupture propagates from the focus and why shaking and damage are not necessarily greatest at the epicenter 6. Describe the different types of seismic waves and how they move through the Earth
- globally, earthquakes located mostly on tectonic plate boundaries - higher frequency = lower magnitude; higher magnitude = lower frequency Plate boundaries+ Faults: 1. Divergent: Plates move apart at mid-ocean ridges & spreading centressmall earthquakes normal dip-slip faults 2. Transform: Plates slide beside each other (shearing) many medium-large earthquakes strike-slip faults 3. Convergent Type 1: Plates collide, causing compression. One plate is more dense and subducts under other small to largest earthquakes (at subduction zone) reverse dip-slip faults 4. Convergent Type 2: Plates collide, causing compression. Neither subducts so crumple, form mountains small to large earthquakes reverse dip-slip faults Constant movement of tectonic plates over many years builds pressure, storing PE. Increased stress breaking, so too much stress causes a slip, releasing energy in an elastic form (reverting to original form) 1. Stress is force/unit area, while strain is how material changes shape from stress. ie.strain is change in shape due to stress 2. Plastic deformation is permanent change, ie. hammering gold sheets. Brittle is breakage, does not hold plastic shape well, ie. hammering glass plate
1. Body Waves: travel in earth (faster than surface waves) in curved pathways (refracted due to earth layers) a) P-wave (primary) particles move back & forth in direction wave is travelling (ex. slinky) b) S-wave (secondary) particles move vertically perpendicular to direction wave is travelling (ex. up&down snake); can’t travel through liquids/water 2. Surface Waves: travel on surface of earth (slower, more damaging than body waves) a) Rayleigh Waveslargest, most damaging; particles rotate backwards, counter clockwise (like ocean)
EOSC 114: Earthquakes Learning Goals b) Love waves: particles move horizontally perpendicular to surface (slithering snake) 7. Understand the principle behind early warning systems (such as the one in Japan) and how much warning time they can give 8. Describe how an earthquake is recorded and how to locate the epicenter
9. Understand how local ground conditions can affect the duration and amplitude of shaking 10. Compare and contrast the meanings and uses of earthquake magnitude and intensity scales 11. Explain the different magnitude scales, which one is best for large quakes, and why
12. Explain factors that determine earthquake intensity
13. Be aware of how earthquakes can be the cause of other natural disasters (e.g., tsunamis, liquefaction, landslides) 14. Understand the basics of how buildings can be designed or retrofitted to better resist earthquakes (and reduce casualties)
-Mainly relative arrival times b/w P-waves and S-waves; larger time difference = farther away -Using distances from 3 recording stations, find the 1 overlapping spot – this is epicentre Type of ground greatly affects shaking intensity hard rocks don’t move as much, softer rocks will move more Magnitude: the strength of an earthquake, on its own Intensity: how much of the earthquake is felt; see 12 -Richter: not used as much now, best for Southern California & seismometer specific; increments of 32x - Moment Magnitude: best because calculates magnitude without estimating ground travel time; uses logarithmic scale, each increment represents 32x stronger magnitude - Note: shaking scale means increments are 10x stronger; magnitude scales are 32x stronger 1. Earthquake magnitude bigger magnitude = higher intensity, if close to people 2. Duration of Shaking longer shaking = higher potential for damage 3. Distance from epicenter/hypocenter usually, more intense the closer to epicenter 4. Ground Typevery important. Hard rocks don’t move as much, softer rocks will. 5. Building Characteristics buildings don’t usually withstand horizontal movement; when moving at building’s resonance frequency, will be more susceptible to damage, feel more intense Liquefaction: soils that are compact when dry will loosen with water and shaking, not strong enough to support buildings -Static Methods:add cross braces (X over window),shear walls (side brace along wall), and shear core (central columnar core) - Dynamic Methods: absorb shock (springs or dampers), change resonant frequency (add mass strategically), and allowing earth to move without building (using isolating foundation w/rubber blocks)
EOSC 114: Earthquakes Learning Goals 15. Identify fault zones that could produce an earthquake damaging to Vancouver 16. Explain what we can and cannot predict about large earthquakes 17. Know the difference between forecasting and prediction
18. Make informed decisions about earthquake safety - how to act, how to prepare
- Cascadia subduction zone fault; Juan de Fuca plate subducts under North American plate - Can predict it will happen within a certain period… but cannot predict exactly when Prediction: very specific…. not going to happen with earthquakes Forecasting: more accurate in short term, fuzzier in long term; like weather forecasting
