Your SlideShare is downloading. ×
  • Like
Earthquakes Lecture
Upcoming SlideShare
Loading in...5

Thanks for flagging this SlideShare!

Oops! An error has occurred.


Now you can save presentations on your phone or tablet

Available for both IPhone and Android

Text the download link to your phone

Standard text messaging rates apply

Earthquakes Lecture



Published in Business , Technology
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
    Be the first to like this
No Downloads


Total Views
On SlideShare
From Embeds
Number of Embeds



Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

    No notes for slide


  • 1. Earthquakes Chapter 19
  • 2. Earthquakes
    • Natural vibrations of ground caused by movement along fractures in Earth’s crust or by volcanic eruptions
  • 3. Stress and Strain
    • Stress- forces per unit area exceed the strength of the rocks involved
      • Compression-Decreases Volume
      • Tension- Pulls material apart
      • Shear- Causes Twisting
    • Strain- Deformation of materials caused by stress
  • 4. Faults- fracture of Earth’s crust
    • Reverse- Horizontal compression, Causes shortening, Foot wall goes down
  • 5. Faults- Con’t
    • Normal- Horizontal tension, Causes extension, Foot wall goes up
  • 6. Faults- Con’t
    • Strike-Slip- Horizontal Shear, causes offset
  • 7.  
  • 8. Waves
    • Primary- P- Pressure Wave
    • Secondary- S- Side-to-side wave
    • Surface Wave- L-Wave
    • Page 498
  • 9. Location of Earthquakes
    • Focus- point where an earthquake originates
    • Epicenter- Place on Earth's surface where EQ occurred
  • 10. Seismic Waves
    • Seismology- Study of Earthquake waves
    • Seismograph- instrument for recording earthquake waves
  • 11. Waves
    • P wave- arrives 1 st
    • S wave- arrives 2nd
    • L wave- last and largest
  • 12. Clues to Earth’s Interior
    • Seismic waves change speed and direction when they encounter different materials
      • P and S waves travel fairly straight through the mantle
      • P waves strike the core and are bent (11,000 Km from focus)
        • Re-emerge at 16,000 km from focus, after shadow
  • 13. Clues to Earth’s Interior- Con’t
    • S-waves cannot travel through liquids so they can’t pass through the core (never beyond shadow)
    • P waves speed up through solids
  • 14.  
  • 15. Measuring and Locating EQ
    • Magnitude- amount of energy released
      • Richter Scale- size of largest seismic waves released by quake
        • Each # increase is a 10 fold increase in energy
        • Each increase in amplitude (height of wave) is a 32 time increase in energy
  • 16. Measuring and Locating EQ- Con’t
    • Moment Magnitude Scale- uses size of fault rupture, amount of movement and rock’s stiffness
    • Modified Mercalli Scale- uses damage to buildings at location of worst damage
      • Uses I-XII Roman Numerals- Called Intensity
      • Measures Surface Waves
    • Depth of Focus- Deeper EQ usually less intense
  • 17. Measuring and Locating EQ-Con’t
    • Locating EQ- time and location unknown
      • Distance determined by time between P wave and S wave--- AT 3 STATIONS
      • Time calculated using same P-S interval
  • 18. Seismic Belts
    • Earthquakes not random
      • Ring of Fire- Edge of Pacific Plate- 80% of all Earthquakes
      • Mediterranean- Asian Belt- 15% of EQ
  • 19.  
  • 20. Earthquakes and Society
    • Earthquake Hazards
      • Structural failure
        • Ground floor fails -> Upper Floors Fail -> Pan caking
        • Height- 5-15 stories causes vibrations which are similar to natural sway; Shorter and taller buildings are different
      • Land/Soil Fracture
        • Landslides- Common in saturated areas
        • Soft ground conducts waves well -> more damage
      • Fault Scarps- vertical offsets -> waterfalls, road problems
  • 21. Earthquakes and Society- Con’t
    • Tsunami- ocean waves created by EQ
      • Travels fast and are low (less than 4 feet high) in open ocean, but pile up hundreds of feet tall near shore
      • Ocean recedes dramatically before tsunami
  • 22. Earthquake Risk
    • Here we have a 3% risk over 50 years
    • Hot Spot in US:
      • CA
      • Rocky Mountains
      • WA, OR
      • MO