Download
earthquakes and the earth s interior an investigation using human subjects n.
Skip this Video
Loading SlideShow in 5 Seconds..
Earthquakes and the Earth's Interior an investigation using human subjects PowerPoint Presentation
Download Presentation
Earthquakes and the Earth's Interior an investigation using human subjects

Earthquakes and the Earth's Interior an investigation using human subjects

124 Vues Download Presentation
Télécharger la présentation

Earthquakes and the Earth's Interior an investigation using human subjects

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Earthquakes and the Earth's Interioran investigation using human subjects College of Central Florida KT Kim

  2. Earthquake • Seismology – study of earthquakes and Earth’s interior using seismic waves

  3. Earthquake • Stress (Force) causes rock to deform • Three types of deformation • Elastic deformation (Vibration, wave propagation) • Plastic deformation (Folds) • Fracturing (Faults)

  4. Earthquake • Earthquake – sudden motion or trembling caused by the abrupt release of energy • Slippage: minor movement (aseismic, fault creep) • Fracture: larger movement (seismic)

  5. Earthquake • Waves propagate through medium • Focus – rupture point where energy is released • Epicenter – point on Earth’s surface above the focus

  6. Seismic Waves • Body waves – travel through Earth’s interior • P wave – compressional elastic wave pressure wave, primary wave • S wave – shear wave, secondary wave • Surface waves – travel through Earth’s surface • Rayleigh waves – rolling (retrogressive) waves • Love waves – Side-to-side waves

  7. Seismic Waves • Measuring seismic waves • Seismograph – the instrument • Seismogram – the record it makes • Measurement of earthquake strength • Mercalli scale – measures damage • Richter scale – measures energy • Moment-magnitude – measures energy as a function of movement and fault surface area

  8. Richter Earthquake Magnitude • Measure S-P time (25 seconds) • Measure the largest amplitude (20 mm) • Plot them on the corresponding axes. • Connect a line. • Read a magnitude (5)

  9. Example 1 • If we compare two earthquakes; one (A) has a magnitude of 5 and the other (B) has a magnitude of 6. What is an amplitude ratio? • Magnitude difference = 6 – 5 = 1 • Amplitude ratio = 101 • Earthquake B has a 10 times bigger amplitude

  10. Example 2 • If we compare two earthquakes; one (A) has a magnitude of 4.5 and the other (B) has a magnitude of 6.5 What is an amplitude ratio? • Magnitude difference = 6.5 – 4.5 = 2 • Amplitude ratio = 102 • Earthquake B has a 100 times bigger amplitude

  11. Example 3 • If we compare two earthquakes; one (A) has a magnitude of 3.7 and the other (B) has a magnitude of 6.7 What is an amplitude ratio? • Magnitude difference = 6.7 – 3.7 = 3 • Amplitude ratio = 103 • Earthquake B has a 1000 times bigger amplitude

  12. Example 4 • If we compare two earthquakes; one (A) has a magnitude of 4.3 and the other (B) has a magnitude of 6.7 What is an amplitude ratio? • Magnitude difference = 6.7 – 4.3 = 2.4 • Amplitude ratio = 102.4 • Earthquake B has a ~251 times bigger amplitude

  13. Locating Earthquakes • P and S waves travel at different speeds • Allows calculation of distance • Time-travel curve • Distance from multiple observations finds a location • Three seismographs

  14. Earthquakes & Tectonic Plates • Where do earthquakes occur? • Convergent boundaries • Divergent boundaries • Transform fault boundaries • Plate interiors

  15. Earthquakes & Tectonic Plates • Convergent boundaries • One plate sliding under another • Benioff zone • Friction along the down-plunging contact zone

  16. Earthquakes & Tectonic Plates • Divergent boundaries • Friction along sliding blocks • Mainly shallow

  17. Earthquakes & Tectonic Plates • Transform boundaries • Offsets ridge system • San Andreas fault zone • Strike-slip fault • Fault is vertical • Plate motion along the line of the fault • Fault creep

  18. Earthquakes & Tectonic Plates • Plate interiors - infrequent • 1811~12 in New Mardrid, MO • Area is still seeing deformation

  19. Earthquake Hazard & Mitigation • Rock and soil – varying responses • Bedrock • Soil type • Topography • Liquefaction • Soil water content • Water table

  20. Earthquake Hazard & Mitigation • Construction design and earthquake damage • Regulation of location and materials • Framing materials • Effects of affluence

  21. Earthquake Hazard Map

  22. Tsunami • Seismic sea wave • Undersea fault motion • Far-traveling wave • Coastal hazard • Sumatra earthquake (2004) • Tohoku earthquake in Japan (2011)

  23. Earthquake Prediction • Long-term prediction • Tells where earthquakes are likely to occur • Short-term prediction • Place and Time • Foreshocks • Aftershocks • Monitoring • China, Japan

  24. Earth’s Interior • Wave behavior • In homogeneous media, wave propagate equally in all directions • Velocity depends on the nature of material waves are traveling through • Waves refract (bend) when moving from one material to another

  25. Earth’s Interior • Moho discontinuity • The crust-mantle boundary • AndrijaMohorovičić (1909) • Waves arrived at distant earthquakes faster than closer ones (Refraction)

  26. Earth’s Interior • Structure of the mantle • 2900 km think • 660 discontinuity • 80 % of Earth’s volume

  27. Earth’s Interior • Discovery of the core • A shadow zone of seismic waves • S wave does not propagate through the liquid medium  outer core is liquid.