Geology: Earthquakes

  1. What is an Earthquake?
    The vibration of Earth produced by the sudden release of energy due to the sudden movement along a fault.
  2. Explain the origin of earthquakes, including their relationship to faults.
    Fault Slips
  3. Describe the occurrence of earthquakes in relation to tectonic plate boundaries.
  4. Where will do you tend to fine shallow earthquakes?
  5. Where will do you tend to find deep-focus earthquakes?
  6. Define Epicenter
    The geographic point on Earth’s surface directly above the focus of an earthquake.
  7. Define Focus
    The point along a fault at which slipping initiates an earthquake.
  8. Briefly discuss elastic rebound and the accumulation of strain.
    How energy dissipates as an earthquake occurs.
  9. What is seismology?
    The study of earthquakes.
  10. List the 3 types of seismic waves and characteristics of each.

    Primary (P) Waves
    • Push-Pull (compress and expand) motion
    • Changes Volume of Material
    • Travel through Solids, Liquids, and Gasses
    • 1.7x faster than S Waves

  11. List the 3 types of seismic waves and characteristics of each.

    Surface (L) Waves
    • Shake at the right angles to direction of travel
    • Travel only through solids
    • Slower than P waves
  12. List the 3 types of seismic waves and characteristics of each.

    Surface (L) Waves
    • Travel along outer part of Earth
    • Cause greatest destruction
    • Greatest periods (time interval between crests)
  13. How would each type of wave record on a seismogram?
  14. Explain how to locate the epicenter of an earthquake.
    1) Determine time interval between arrival of P and S wave (lag time)

    2) Use travel time graph to determine distance from epicenter

    3) Draw circle with radius equal to distance to epicenter around each station. Repeat for 3 stations

    4) Epicenter is the point where all three circles intercept
  15. Discuss the measurement of earthquake intensity and magnitude.
    Intensity measures the degree of shaking at a location based on amount of damage.

    Magnitude estimates the amount of energy released at the earthquake source.
  16. Explain the use and limitations of the modified Mercalli Intensity scale.
    Measures the intensity of an earthquake from the amount of damage it causes.

    Destruction is not always a true measure of an earthquake's actual severity.
  17. Compare and contrast the Richter scale and moment magnitude scale.
    Richter Scale developed for shallow, local earthquakes and does not work well for large earthquakes. Based on amplitude of largest seismic wave.

    Moment Magnitude Scale is useful for both large and small earthquakes. Based on fault area and average displacement along a fault.
  18. Discuss some of the factors that determine the extent of damage produced by a given earthquake.
    • Intensity of the vibrations
    • Duration of the vibrations

    • What material the structure is sitting on
    • Design of the structure
    •      -Seismic Waves may be amplified due to subsurface material and building height.
  19. List and describe several hazards associated with earthquakes.
    • -Shaking
    • -Liquefaction of the ground (Solid earth liquifies -unsaturated mud)
    • -Seiches (Rhythmic slashes of water)
    • -Tsunamis (Seismic sea waves)
    • -Landslides
    • -Fires
  20. Explain earthquake prediction in terms of both short-range and long-range forecasting.
    Short-ranged forecasts - Cannot be predicted

    Long-ranged forecasts - Can be predicted based of premise that earthquakes are repetitive

    • 30-100 years
    • Rupture zone tend to be adjacent
  21. Identify the 3 most important faults in the SF Bay Area.
    • San Andreas Fault
    • Hayward Fault
    • Rodgers Creek Fault
  22. Should we be concerned about earthquakes here in Redwood City?  Explain.
    Yes. Redwood City is adjacent to the San Andreas Fault.
  23. List steps you should take to prepare for an earthquake and items you should include in an earthquake kit.
    1) Identify Potential Hazards in Your Home and Begin to Fix Them

    2) Create a Disaster-Preparedness Plan

    3) Prepare Disaster Kits

    4) Identify Your Building’s Potential Weaknesses and Begin to Fix Them

    5) Protect Yourself During Earthquake Shaking

    6) Check for Injuries and Damage Post Quake

    7) Continue to Follow Your Disaster-Preparedness Plan When It's Safe
  24. List items you should include in an earthquake kit.

    First Aid Kit

    Bottled Water

    High Calorie Snack Foods

    Emergency Cash
  25. What should you do if you feel an earthquake?
    Brace yourself in-between a door way
Card Set
Geology: Earthquakes
Study Guide for Geology: Earthquakes