0
Earthquakes
 
Global Seismicity
Continental Drift Animation based on paleomaps from  University of Texas Arlington
Plate tectonics:  predicting the future
Plate tectonics in the future: 50 my <ul><li>Australia will straddle the equator </li></ul><ul><li>E. Africa will form new...
Global Seismicity
Rocks are stressed too… <ul><li>Rock stress:  from tectonic forces, gravity, and weight of rocks above </li></ul><ul><li>T...
Strain <ul><li>= how rocks respond to stress </li></ul><ul><li>2 types </li></ul><ul><li>folding (bending) </li></ul><ul><...
Types of folds <ul><li>Anticline  </li></ul><ul><ul><li>simple upfold </li></ul></ul><ul><ul><li>layers slope down from ax...
Types of folds syncline anticline overturned anticline
Types of Faults Tension Compression Shear Stretching Shortening Twisting
Faulting <ul><li>= rocks on either side of a fracture are displaced relative to each other </li></ul><ul><li>Earthquake:  ...
Anatomy of a fault <ul><li>Fault scarp  = steep cliffs that make up the edge of a displaced block </li></ul>
3 Types of Faults <ul><li>Normal </li></ul><ul><ul><li>tension </li></ul></ul><ul><li>Reverse </li></ul><ul><ul><li>compre...
3 Types of Faults
3 Types of Faults Divergent Plate Boundaries
3 Types of Faults Convergent Plate Boundaries
3 Types of Faults Transform Plate Boundaries
Earthquakes <ul><li>= vibration in the Earth </li></ul><ul><li>produced by shockwaves from sudden movements along faults <...
Focus vs epicenter <ul><li>Focus  = center of fault motion </li></ul><ul><li>Epicenter  = surface directly above focus </l...
Seismometer
Seismogram
Richter Scale Scale is  exponential For every increase of 1 in the Richter scale,  the  wave amplitude   increases x10 Exp...
a = 10 M Where  M is Richter magnitude, and  a is wave amplitude M = log 10 (a) Which is the same as Richter Scale Scale i...
But  wave amplitude   is not the same as  energy released .  (see pg 408 in Strahler) E = 10 (4.8+1.5M)  = 10 4.8  ·10 1.5...
How much energy is released? <ul><li>For example, the earthquake that caused the Indian Ocean tsunamis on Boxing Day 2004 ...
The Boxing Day Quake <ul><li>How much energy was released by this quake? </li></ul><ul><li>E = 10 (4.8 + 1.5M) </li></ul><...
Upcoming SlideShare
Loading in...5
×

Lecture11 earthquakes

319

Published on

Published in: Technology, Education
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
319
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
12
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Transcript of "Lecture11 earthquakes"

  1. 1. Earthquakes
  2. 3. Global Seismicity
  3. 4. Continental Drift Animation based on paleomaps from University of Texas Arlington
  4. 5. Plate tectonics: predicting the future
  5. 6. Plate tectonics in the future: 50 my <ul><li>Australia will straddle the equator </li></ul><ul><li>E. Africa will form new continent </li></ul><ul><li>Antarctica will swing off the south pole </li></ul><ul><li>Mediterranean will close off </li></ul><ul><li>Atlantic Ocean will grow </li></ul><ul><li>Pacific Ocean will shrink </li></ul>
  6. 7. Global Seismicity
  7. 8. Rocks are stressed too… <ul><li>Rock stress: from tectonic forces, gravity, and weight of rocks above </li></ul><ul><li>Types of stress </li></ul><ul><li>Tension (stretching) </li></ul><ul><li>Compression (shortening) </li></ul><ul><li>Shear (twisting or tearing) </li></ul>
  8. 9. Strain <ul><li>= how rocks respond to stress </li></ul><ul><li>2 types </li></ul><ul><li>folding (bending) </li></ul><ul><li>faulting (breaking) </li></ul>depends on rock composition, pressure, and rock characteristics (brittle vs. ductile)
  9. 10. Types of folds <ul><li>Anticline </li></ul><ul><ul><li>simple upfold </li></ul></ul><ul><ul><li>layers slope down from axis </li></ul></ul><ul><ul><li>younger on outside </li></ul></ul><ul><li>Syncline </li></ul><ul><ul><li>simple downfold </li></ul></ul><ul><ul><li>layers slope up from axis </li></ul></ul><ul><ul><li>younger on inside </li></ul></ul>younger older younger older
  10. 11. Types of folds syncline anticline overturned anticline
  11. 12. Types of Faults Tension Compression Shear Stretching Shortening Twisting
  12. 13. Faulting <ul><li>= rocks on either side of a fracture are displaced relative to each other </li></ul><ul><li>Earthquake: caused by sudden release of energy along a fault </li></ul>
  13. 14. Anatomy of a fault <ul><li>Fault scarp = steep cliffs that make up the edge of a displaced block </li></ul>
  14. 15. 3 Types of Faults <ul><li>Normal </li></ul><ul><ul><li>tension </li></ul></ul><ul><li>Reverse </li></ul><ul><ul><li>compression </li></ul></ul><ul><li>Strike-slip (transcurrent) </li></ul><ul><ul><li>shearing </li></ul></ul><ul><ul><li>lateral displacement </li></ul></ul>
  15. 16. 3 Types of Faults
  16. 17. 3 Types of Faults Divergent Plate Boundaries
  17. 18. 3 Types of Faults Convergent Plate Boundaries
  18. 19. 3 Types of Faults Transform Plate Boundaries
  19. 20. Earthquakes <ul><li>= vibration in the Earth </li></ul><ul><li>produced by shockwaves from sudden movements along faults </li></ul>Seismic = pertaining to earthquakes
  20. 21. Focus vs epicenter <ul><li>Focus = center of fault motion </li></ul><ul><li>Epicenter = surface directly above focus </li></ul>
  21. 22. Seismometer
  22. 23. Seismogram
  23. 24. Richter Scale Scale is exponential For every increase of 1 in the Richter scale, the wave amplitude increases x10 Exponential decay Exponential growth y = y 0 e -kx y = e kx
  24. 25. a = 10 M Where M is Richter magnitude, and a is wave amplitude M = log 10 (a) Which is the same as Richter Scale Scale is exponential For every increase of 1 in the Richter scale, the wave amplitude increases x10
  25. 26. But wave amplitude is not the same as energy released . (see pg 408 in Strahler) E = 10 (4.8+1.5M) = 10 4.8 ·10 1.5M Where M is Richter magnitude, and E is energy released So for every increase of 1 in the Richter magnitude, energy increases x 32 Richter Scale
  26. 27. How much energy is released? <ul><li>For example, the earthquake that caused the Indian Ocean tsunamis on Boxing Day 2004 (12/26/04) measured 9 on the Richter scale </li></ul><ul><li>How much energy was released by this quake? </li></ul><ul><ul><li>E = 10 (4.8 + 1.5M) </li></ul></ul>
  27. 28. The Boxing Day Quake <ul><li>How much energy was released by this quake? </li></ul><ul><li>E = 10 (4.8 + 1.5M) </li></ul><ul><li>= 10 (4.8 + 1.5(9)) </li></ul><ul><li>= 10 (4.8 + 13.5) </li></ul><ul><li>= 10 (18.3) = 1.99 x 10 18 J </li></ul>For comparison, the average U.S. electric power consumption rate is 3 x 10 12 J/sec
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×