1. Diastrophism Processes Breaking & Warping Earth
Faults and Folds Part 2
Diastrophism Processes
Breaking & Warping Earth

2. Faults and Folds Transform – Strike-slip faulting
Extension - Normal faulting (part 1)
Compression - Thrust faulting (part 1)
Transform – Strike-slip faulting
Folding from Compression

3. 3. Transform – Strike-slip faulting
NORTH AMERICA
36 mm/yr
PACIFIC
San Andreas Fault, Carrizo Plain

4. Classroom Resource

7. Online Videos 1906 San Francisco Earthquake

8. 1906 S.F. Quake

10. 1989 LOMA PRIETA, CALIFORNIA EARTHQUAKE
MAGNITUDE 7.1 ON THE SAN ANDREAS
Davidson et al

11. Classroom Resources

12. Cal Memorial Stadium

13. 1989 LOMA PRIETA, CALIFORNIA EARTHQUAKE
The two level Nimitz freeway collapsed along
a 1.5 km section in Oakland, crushing cars
Freeway had been scheduled for retrofit to improve earthquake resistance

14. Houses collapsed in the Marina district of San Francisco
1989 LOMA PRIETA, CALIFORNIA EARTHQUAKE
Houses collapsed in the Marina district of San Francisco
Shaking amplified by low velocity landfill
Stein & Wysession (USGS)

15. Over time, slip in earthquakes adds up and reflects the plate motion
Offset fence showing 3.5 m of left-lateral strike-slip motion along San Andreas fault in 1906 San Francisco earthquake
~ 35 mm/yr motion between Pacific and North American plates along San Andreas shown by offset streams & GPS
Expect earthquakes on average every ~ (3.5 m )/ (35 mm/yr) =100 years
Turns out more like 200 yrs because not all motion is on the San Andreas
Moreover, it’s irregular rather than periodic

16. EARTHQUAKE RECURRENCE IS HIGHLY VARIABLE
Reasons are unclear: randomness, stress effects of other earthquakes on nearby faults…
Extend earthquake history with paleoseismology
Sieh et al., 1989
M>7 mean 132 yr s 105 yr
S&W

17. In general, the most destructive earthquakes occur where large populations live near plate boundaries. The highest property losses occur in developed nations where more property is at risk, whereas fatalities are highest in developing nations.
Estimates are that the 1990 Northern Iran shock killed 40,000 people, and that the Spitak (Armenia) earthquake killed 25,000. Even in Japan, where modern construction practices reduce earthquake damage, the 1995 Kobe earthquake caused more than 5,000 deaths and $100 billion of damage. On average during the past century earthquakes have caused about 11,500 deaths per year.
The earthquake risk in the United States is much less than in many other countries because large earthquakes are relatively rare in most of the U.S. and because of earthquake-resistant construction

18. San Andreas Fault
Helps Set
Topography

19. More Dangerous: LA riddled with unknown faults

20. INLAND EMPIRE Southern California San Bernardino Mountains
Cucamonga fault
San Andreas fault
San Jacinto fault
INLAND EMPIRE
Southern California

21. Recent mudslide scars
Cucamonga fault scarp

22. Pads for 47 new homes
SAN ANDREAS FAULT

25. Classroom Resources
Shaking Wet Sand Italy Example

26. Highest
Liquefaction
Potential

27. (adjacent to the San Andreas fault)

28. Classroom Resources
What will happen when a big one hits the “Inland Empire”
Animation of the future quake

29. Landforms of a Strike-Slip Fault

31. Classroom Resource
“Spin Around” QTVR at Offset Drainage, Wallace Creek, San Andreas Fault

32. Strike-Slip Faulting elsewhere, too in Turkey & Levant

33. Quake in Turkey

34. Quake in Turkey

35. 4. Folding from Compression

36. Faulting
Relationship Between Stress and Strain at low Temps and Pressure or Sudden Stress

37. Relationship Between Stress and Strain under high Temps or Pressure
Folding

38. Monocline – single bend

39. Single bend
Flat- lying
Flat- lying

42. Anticline fold
from:

43. Folded Rocks, Hwy 23 Newfoundland, New Jersey
Adjacent Anticline and Syncline
Source: Breck P. Kent

44. Anticlines and Oil
Early USA petroleum exploration, e.g. Pennsylvania anticlines

45. Folded Rock Before Erosion

46. Folds Erode Creating Flatirons (hard layers on side of anticline fold)

48. Fold Erosion creates Hogbacks from a side of the fold

49. Banff, Canada

50. Classroom Resource
QTVR “spin arounds” to see hogbacks and monoclines (Waterpocket, San Rafael Swell)

51. Folded Rock After Erosion
Eroded Anticline, older rocks in center. Syncline is opposite.

52. Topography may be opposite of Structure Anticline Before/After Erosion
Notice center rock oldest

53. Topography may be opposite of Structure Syncline Before/After Erosion
Notice center rock youngest

54. Synclinal Ridge
Hard strata last preserved at the bottom of the syncline, holding up the weaker rock

55. Synclinal Mountain, Canada

56. Synclinal Mountain, Mt Everest

57. Lazy Path of Rivers: Erode rock in the weak strata creating “strike valley”

58. Namibia: Most of the streams (dry washes) flow between hogbacks
But Ugab River cuts across the hard layers (hogbacks). Why? How?

59. Transverse Streams that cut right across fold belts & horsts
Why didn’t the Susquehanna River go around the fold? Why did it go through?
Transverse Streams that cut right across fold belts & horsts

60. How did the Columbia River get through the Cascades?

61. How did this stream cross the Anticline in the Zagros Mountains?

63. Overflow of an ancient lake most common explanation in the west
Ancient Lake Roosevelt Overflowed

64. Lake Overflow led to Grand Canyon Formation

65. Classroom Resource
Modeling how streams get across uplifts

66. Imagery seen in this presentation is courtesy of Ron Dorn and other ASU colleagues, students and colleagues in other academic departments, individual illustrations in scholarly journals such as Science and Nature, scholarly societies such as the Association of American Geographers, city,state governments, other countries government websites and U.S. government agencies such as NASA, USGS, NRCS, Library of Congress, U.S. Fish and Wildlife Service USAID and NOAA.cs